Document:

EX-10.2

 Exhibit 10.2 
 SECOND AMENDED AND RESTATED 
 STOCKHOLDERS’ AGREEMENT 

THIS SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT (the “Agreement”) is made and entered into
as of December 28, 2012, by and among ARATANA THERAPEUTICS, INC., a Delaware corporation (the “Company”), each of the holders of Series C Preferred Stock (as defined below) listed on Exhibit A
hereto (the “Series C Preferred Holders”), each of the holders of Series B Preferred Stock (as defined below) listed on Exhibit B hereto (the “Series B Preferred
Holders”), each of the holders of Series A Preferred Stock (as defined below) listed on Exhibit C hereto (the “Series A Preferred Holders”), each of the holders of Series A-1 Preferred
Stock (as defined below) listed on Exhibit D hereto (the “Series A-1 Preferred Holders” and, together with the Series B Preferred Holders and the Series A Preferred Holders, the
“Preferred Holders”), each of the holders of Common Stock (as defined below) listed on Exhibit E hereto (the “Common Holders” and collectively with the Series A Preferred Holders and
the Series A-1 Preferred Holders, the “Existing Holders”) and each Additional Holder (as defined below) who shall, after the date hereof, acquire shares of Common Stock and become a party to this Agreement as a
“Common Holder” by executing and delivering to the Company an Instrument of Accession in the form of Exhibit F hereto. The Common Holders (including any Additional Holders) and the Preferred Holders are sometimes refereed to
herein individually as a “Stockholder” and collectively as the “Stockholders”. 

RECITALS 

WHEREAS, the Company and the Series A Preferred Holders are parties to that certain Series A Preferred Stock Purchase
Agreement, dated as of December 27, 2010 (the “Series A Purchase Agreement”), and the Company and the Series A-1 Preferred Holders are parties to that certain Series A-1 Preferred Stock Purchase Agreement,
dated as of December 27, 2010 (the “Series A-1 Purchase Agreement” and, together with the Series A Purchase Agreement, the “Prior Purchase Agreements”); 

WHEREAS, as a condition of entering into the Prior Purchase Agreements, the Existing Holders and the Company executed that certain
Stockholders’ Agreement dated as of December 27, 2010 among the Company and the Existing Holders (the “Prior Agreement”); 
 WHEREAS, the Series B Preferred Holders are parties to that certain Series B Preferred Stock Purchase Agreement, dated as of November 1, 2011, among the Company and the Series B
Preferred Holders (the “Series B Purchase Agreement”); 
 WHEREAS, as a condition of
entering into the Series B Purchase Agreement the Series B Preferred Holders, the Existing Holders and the Company executed that certain First Amended and Restated Stockholders’ Agreement, dated as of November 1, 2011 (the
“Restated Prior Agreement”); 
 WHEREAS, the Series C Preferred Holders are parties to that
certain Series C Preferred Stock Purchase Agreement of even date herewith among the Company and the Series C Preferred Holders (the “Series C Purchase Agreement”); and 

 WHEREAS, the Series C Preferred Holders have requested that the Company and
Series B Preferred Holders and Existing Holders representing at least the Majority Investors (as defined in the Restated Prior Agreement) amend and restate the Restated Prior Agreement as set forth below, as an inducement to the Series C
Preferred Holders to enter into the Series C Purchase Agreement. 
 NOW THEREFORE, in consideration of the foregoing
recitals and the mutual promises, representations, warranties, and covenants hereinafter set forth and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Series B Preferred Holders and
the Existing Holders hereby agree that the Restated Prior Agreement shall be amended and restated, and the parties to this Agreement further agree as follows: 
 AGREEMENT 
 1. CERTAIN DEFINITIONS. For purposes of this Agreement: 

1.1 The term “Avalon Major Investor” shall mean, collectively, Avalon Ventures IX, L.P. and each Permitted
Transferee (as defined below) thereof. 
 1.2 The term “Certificate of Incorporation” shall mean
that certain Third Amended and Restated Certificate of Incorporation of the Company of even date herewith. 
 1.3 The
term “Company Transaction” shall mean any: (i) acquisition of the Company by another entity or person unaffiliated with any Stockholder by means of any transaction or series of related transactions (including, without
limitation, any reorganization, merger, consolidation, tender offer or stock sale) that results in the transfer of at least a majority of the then-outstanding voting power of the Company; or (ii) sale of all or substantially all of the assets
of the Company to an entity or person unaffiliated with any Stockholder. 
 1.4 The term “Major
Holders” shall have the meaning set forth in that certain Second Amended and Restated Investors’ Rights Agreement, dated as of even date herewith, by and among the Company and the investors named therein. 

1.5 The term “Majority Investors” shall mean and include the Avalon Major Investor and the MPM Major
Investor; provided, however, that to the extent that any of the foregoing ceases to hold shares of Series A Preferred Stock, Series B Preferred Stock or Series C Preferred Stock, such entity shall no longer be a Majority
Investor. 
 1.6 The term “Major Series B Subject Holders” shall mean Subject Holders who
hold at least 333,333 shares of Series B Preferred Stock. 
 1.7 The term “Major Series C Subject
Holders” shall mean Subject Holders who hold at least 250,000 shares of Series C Preferred Stock. 
 1.8
The term “MPM Major Investor” shall mean, collectively, MPM BioVentures V, L.P. and each Permitted Transferee thereof. 

  
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 1.9 The term “Restricted Holder” shall mean and include the
Common Holders (including any Additional Holders), the Subject Holders (as defined below) and the Series A-1 Preferred Holders. 
 1.10 The term “Series A Directors” shall mean and includes the Avalon Director (as defined below), the MPM Director (as defined below) and the Additional Series A
Director (as defined below). 
 1.11 The term “Subject Holders” shall mean the Series C
Preferred Holders who are not Existing Holders or affiliates of Existing Holders and the Series B Preferred Holders who are not Existing Holders or affiliates of Existing Holders. 
 2. VOTING OF STOCKHOLDER SHARES. 
 2.1 Shares Held Subject to
Agreement. Each of the Stockholders agrees to hold all shares of capital stock of the Company registered in its respective name or beneficially owned by it as of the date hereof and any and all other securities of the Company legally or
beneficially acquired by it after the date hereof, including, without limitation, any shares of capital stock issuable upon exercise or conversion of securities exercisable for or convertible into shares of the Company’s capital stock
(hereinafter collectively referred to as the “Stockholder Shares”) subject to, and, at any time when entitled, to vote the Stockholder Shares in accordance with, the provisions of this Section 2. 

2.2 Size of Board of Directors. Subject to Section 2.3(a), each Stockholder shall, at all times when entitled to vote or give
a written consent with respect to such matter, vote at all regular or special meetings of stockholders, and shall give written consent with respect to, all Stockholder Shares so as to set and maintain the number of authorized directors comprising
the Company’s Board of Directors (the “Board of Directors”) at seven (7) directors. 
 2.3
Election of Directors. 
 (a) At each election of directors in which the holders of the Company’s Common Stock
(the “Common Stock”), the holders of the Company’s Series C Preferred Stock (the “Series C Preferred Stock”), the holders of the Company’s Series B Preferred Stock (the
“Series B Preferred Stock”), the holders of the Company’s Series A Preferred Stock (the “Series A Preferred Stock”) and/or the holders of the Company’s Series A-1
Preferred Stock (the “Series A-1 Preferred Stock” ), whether voting together as a single class or each voting as a separate class, are entitled to elect directors of the Company, the Stockholders shall, at all times when
entitled to vote or give a written consent with respect to, vote (or shall consent to vote pursuant to an action by written consent of the holders of capital stock of the Company) all of their respective Stockholder Shares so as to elect:

 (i) for so long as the Avalon Major Investor is a Majority Investor, one (1) designee of the Avalon Major
Investor (the “Avalon Director”), which designee shall initially be Jay Lichter, to serve as one (1) of the three (3) directors to be elected by the holders of a majority of the then-outstanding shares of
Series A Preferred Stock, voting as a separate class; 

  
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 (ii) for so long as the MPM Major Investor is a Majority Investor, one
(1) designee of the MPM Major Investor (the “MPM Director”), which designee shall initially be John Vander Vort, to serve as one (1) of the three (3) directors to be elected by the holders of a majority of the
then-outstanding shares of Series A Preferred Stock, voting as a separate class; 
 (iii) one (1) designee
that is designated by the holders of at least seventy-five percent (75%) of the then-outstanding shares of Series A Preferred Stock (the “Additional Series A Director”), which designee shall initially be Ron
Meeusen, to serve as one (1) of the three (3) directors to be elected by the holders of a majority of the then-outstanding shares of Series A Preferred Stock, voting as a separate class; 

(iv) one (1) designee that is designated by the holders of a majority of the then-outstanding shares of Series C
Preferred Stock and Series B Preferred Stock, voting together as a single class on an as-if-converted to Common Stock basis (the “Series B/C Director”) to serve as one (1) of the remaining directors, which
designee shall initially be Linda Rhodes; 
 (v) one (1) designee that is designated by the holders of a majority
of the then-outstanding shares of Common Stock held by the Common Holders, which designee shall in all cases be the person serving as the Chief Executive Officer of the Company (the “CEO Director”), which shall initially be
Steven St. Peter, to serve as one (1) of the remaining directors; and 
 (vi) other designees that are acceptable
to a majority of the Series A Directors as independent members of the Board of Directors (the “Independent Directors”), which designees shall initially be Craig Tooman and Rip Gerber, to serve as the remaining directors.

 (b) Any vote taken to remove any director elected pursuant to this Section 2.3, or to fill any vacancy created by
the resignation, removal or death of a director elected pursuant to this Section 2.3, shall also be subject to the provisions of this Section 2.3. 
 (c) None of the parties hereto and no officer, director, stockholder, partner, employee or agent of any such party makes any representation or warranty as to the fitness or competence of the
nominee of any party hereunder to serve on the Board of Directors by virtue of such party’s execution of this Agreement or by the act of such party in voting for such nominee pursuant to this Agreement. 

(d) The Company agrees that it shall, at the request of any Stockholder or group of Stockholders entitled to designate directors
pursuant to Section 2.3(a), promptly take all actions necessary (pursuant to the Company’s bylaws, the laws of the State of Delaware or otherwise) to call and conduct a special meeting of the stockholders of the Company for the purpose of
electing directors in accordance with the provisions of Section 2.3(a). 
 2.4 Drag Along. 

(a) In the event that the Board of Directors and the Majority Investors approve any Company Transaction, each Stockholder will
vote (to the extent such Stockholder is entitled 

  
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to vote) for, consent to and raise no objections to such Company Transaction. Each Stockholder will waive any dissenter’s rights, appraisal rights or similar rights, to the extent
applicable, in connection with any such Company Transaction. If the Company Transaction is structured as a sale of stock, each Stockholder will agree to sell all of its Stockholder Shares and rights to acquire Stockholder Shares pursuant to the
terms and conditions approved by the Board of Directors and the Majority Investors. Each Stockholder will take all necessary or desirable actions in connection with the consummation of the Company Transaction as requested by the Board of Directors
and the Majority Investors including, without limitation, delivering such Stockholder’s stock certificates free and clear of all liens and encumbrances (other than those arising under applicable securities laws). 

(b) Notwithstanding the foregoing Section 2.4(a), a Stockholder will not be required to comply with Section 2.4(a) in
connection with any Company Transaction unless: 
 (i) any representations and warranties to be made by such Stockholder
in connection with the Company Transaction are limited to representations and warranties related to authority, ownership and the ability to convey title to such Stockholder Shares, including but not limited to representations and warranties that:
(w) the Stockholder holds all right, title and interest in and to the Stockholder Shares such Stockholder purports to hold, free and clear of all liens and encumbrances; (x) the obligations of the Stockholder in connection with the Company
Transaction have been duly authorized, if applicable; (y) the documents to be entered into by the Stockholder have been duly executed by the Stockholder and delivered to the acquirer and are enforceable against the Stockholder in accordance
with their respective terms; and (z) neither the execution and delivery of documents to be entered into in connection with the Company Transaction, nor the performance of the Stockholder’s obligations thereunder, will cause a breach or
violation of the terms of any agreement, law or judgment, order or decree of any court or governmental agency; 
 (ii)
the Stockholder shall not be liable for the inaccuracy of any representation or warranty made by any other individual or entity (other than the Company) in connection with the Company Transaction; 

(iii) the liability for indemnification, if any, of such Stockholder in the Company Transaction and for the inaccuracy of any
representations and warranties made by the Company or breaches by the Company of its covenants made in any acquisition agreement in connection with such Company Transaction, is several and not joint with any other individual or entity and is pro
rata in proportion to, and does not exceed, the amount of consideration paid to such Stockholder in connection with such Company Transaction; and 
 (iv) The consideration paid to the Stockholders will be distributed pursuant to Section 3 of the Certificate of Incorporation, as if such Company Transaction were an Acquisition. 

2.5 Vote to Increase Authorized Common Stock. Each Stockholder shall, at all times when entitled to vote with respect to such
matter, vote (or shall, at all times when entitled to vote with respect to such matter, consent to vote pursuant to an action by written consent of the holders of capital stock of the Company) all of its respective Stockholder Shares as shall be

  
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necessary to increase the number of authorized shares of Common Stock from time to time to ensure that there are sufficient shares of Common Stock available for conversion of all of the shares of
Series C Preferred Stock, Series B Preferred Stock, Series A Preferred Stock and Series A-1 Preferred Stock outstanding at any such time. 
 2.6 Irrevocable Proxy. Each Stockholder hereby constitutes and appoints the CEO Director as the attorney and proxy of such Stockholder, with full power of substitution, with respect to the matters
set forth in this Section 2, and hereby authorizes the CEO Director to represent and to vote all of the Stockholder Shares held by such Stockholder in accordance with the provisions set forth in this Section 2; provided,
however, that such proxy shall be in effect and exercisable if and only if the Stockholder granting such proxy: (i) fails to vote altogether on a matter covered by this Section 2; or (ii) attempts to vote on a matter covered by
this Section 2 in a manner other than as provided by this Section 2. The proxy granted pursuant to this Section 2.6 is coupled with an interest and shall be irrevocable unless and until the provisions of this Section 2 terminate
pursuant to the provisions of Section 2.7 below. Each Stockholder hereby revokes any and all previous proxies granted with respect to the Stockholder Shares held by such Stockholder and agrees not to grant any other proxy or power of attorney
with respect to such Stockholder Shares or to deposit any of such Stockholder Shares into a voting trust or to enter into any similar agreement, arrangement or understanding with any other person with respect to the voting of any Stockholder Shares
held by such Stockholder unless and until the provisions of this Section 2 terminate pursuant to the provisions of Section 2.7 below. 
 2.7 Termination of Voting Provisions. The provisions of this Section 2 shall continue in full force and effect from the date hereof through the earliest of the following dates, on which date
such provisions shall terminate and cease to be in effect: (i) the date of the closing of a firmly underwritten public offering of the Common Stock pursuant to a registration statement filed with the Securities and Exchange Commission (the
“SEC”) and declared effective under the Securities Act of 1933, as amended (the “Securities Act”); or (ii) the date of the closing of a sale, lease or other disposition of all or substantially all
of the Company’s assets or the Company’s merger into or consolidation with any other corporation or other entity, or any other corporate reorganization, in which the holders of the Company’s outstanding voting stock immediately prior
to such transaction own, immediately after such transaction, securities representing less than fifty percent (50%) of the voting power of the corporation or other entity surviving such transaction; provided, however, that this
clause “(ii)” shall not apply to a merger effected exclusively for the purpose of changing the domicile of the Company. 
 3.
RESTRICTIONS ON TRANSFERS BY STOCKHOLDERS. 
 3.1 General Restriction. Each Restricted Holder agrees that such
Restricted Holder shall not sell, assign, transfer, pledge, hypothecate, mortgage or dispose of, by gift or otherwise, or in any way encumber (collectively, “Transfer”), all or any part of the Stockholder Shares held by such
Stockholder other than in compliance with Sections 3.2 and 3.3 below. 

  
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 3.2 Right of First Refusal. 

(a) Subject to Section 3.8 below, if at any time any Restricted Holder desires to Transfer in any manner any Stockholder
Shares held by such Restricted Holder pursuant to the terms of a bona fide written offer received from a third party (the “Restricted Holder Buyer”), such Restricted Holder (the “Selling Restricted
Holder”) shall submit a written offer (the “Restricted Holder Offer”) to sell such Stockholder Shares (the “Offered Stockholder Shares”) to the Company at the same price and on the same
terms and conditions on which the Selling Restricted Holder proposes to sell such Offered Stockholder Shares to the Restricted Holder Buyer. The Restricted Holder Offer shall disclose the identity of the proposed Restricted Holder Buyer, the number
of Offered Stockholder Shares, the terms of the proposed Transfer, including price, and any other material facts, terms and conditions relating to the proposed Transfer. Within thirty (30) days after receipt of the Restricted Holder Offer, the
Company shall give notice to the Selling Restricted Holder of its intent to purchase all or a portion of the Offered Stockholder Shares from the Selling Restricted Holder on the terms and conditions set forth in the Restricted Holder Offer. Such
notice shall specify the time, place and date for settlement of such purchase, which shall be consummated at a closing held at the Company within the thirty (30) day period specified above. 

(b) If the Company does not elect to purchase all of the Offered Stockholder Shares as provided in Section 3.2(a), the
Company shall, within five (5) days after expiration of the thirty (30) day period specified in Section 3.2(a), provide each Major Holder with written notice (the “ROFR Notice”) of such election, which ROFR
Notice shall include a copy of the Restricted Holder Offer provided to the Company pursuant to Section 3.2(a). Each Major Holder shall then have the right, exercisable within thirty (30) days following receipt of the ROFR Notice, to
purchase up to that number of the Offered Stockholder Shares that the Company elected not to purchase from such Selling Restricted Holder (all such remaining shares being referred to as the “Remaining Offered Stockholder
Shares”) equal to the aggregate Remaining Offered Stockholder Shares multiplied by a fraction: (i) the numerator of which is the number of Stockholder Shares held by such Major Holder; and (ii) the denominator of which is the
aggregate number of Stockholder Shares held by all of the Major Holders (such amount to be referred to as a Major Holder’s “Major Holder ROFR Pro Rata Share”). In the event that a Major Holder does not wish to purchase
its full Major Holder ROFR Pro Rata Share, then any Major Holder who has elected to purchase its full Major Holder ROFR Pro Rata Share shall have the right to purchase, on a pro rata basis with any other Major Holders who so elect, any Remaining
Offered Stockholder Shares not purchased. If exercised by the Major Holders pursuant hereto, the right to purchase the Offered Stockholder Shares or the Remaining Offered Stockholder Shares, as the case may be, shall be exercised by written notice,
signed by the Company and the participating Major Holders, and delivered to the Selling Restricted Holder prior to the expiration of the thirty (30) day notice period specified above. Such notice shall specify the time, place and date for
settlement of such purchase, which shall be consummated at a closing held at the Company within ten (10) days after the expiration of the thirty (30) day notice period specified above. 

(c) For the purposes of this Section 3.2, the number of Stockholder Shares held by a Major Holder shall include the holdings
of Permitted Transferees of such Major Holder, and such holdings shall be aggregated together with that of such Major Holder. As used 

  
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in this Agreement, the term “Permitted Transferee” means: (i) in the case of a Stockholder that is a partnership, any constituent partner of such partnership and any
affiliated partnership, limited liability company or other entity managed by the same management company or general partner or any affiliate of such management company or general partner; (ii) in the case of a Stockholder that is a limited
liability company, any member of such limited liability company and any affiliated limited liability company, partnership or other entity managed by the same management company or member or any affiliate of such management company or member;
(iii) in the case of a Stockholder that is an individual, the spouse, children, grandchildren or spouse of such children or grandchildren of such person or to trusts for the benefit of such person or such person’s spouse, children,
grandchildren or spouse of such children or grandchildren; (iv) in the case of a Stockholder that is a trust, any beneficiary of such trust; (v) in the case of the Kansas Bioscience Authority (or its successor or replacement entity), any
successor or replacement entity formed by or as an instrumentality or authority of the State of Kansas; (vi) in the case of the Ewing Marion Kauffman Foundation (or its successor or replacement entity), to any successor or replacement entity
formed by the Ewing Marion Kauffman Foundation for the purpose of holding equity investments, or any entity under common investment management with any such successor or replacement entity; and (vii) in the case of a Company Transaction
approved by the Board of Directors and the Majority Investors pursuant to Section 2.4, the transferee approved by the Board of Directors and the Majority Investors pursuant to the terms and conditions approved by the Board of Directors and the
Majority Investors. 
 (d) Except as set forth in Section 3.8 below, in the event that the Company and the Major
Holders, on a collective basis, do not elect to purchase all of the Offered Stockholder Shares pursuant to and within the time periods set forth above, then the Company and the Stockholders shall be deemed to have forfeited any right to purchase the
Offered Stockholder Shares, and, subject to Section 3.3 and Section 3.8, the Selling Restricted Holder shall be free for a period of sixty (60) days thereafter, to sell all, but not less than all, of the Offered Stockholder Shares to
the Restricted Holder Buyer, if the Restricted Holder Buyer agrees in writing to be bound by the terms of this Agreement in the same capacity as the Selling Restricted Holder. Any such Transfer shall be at the same price per share, and upon the same
terms and conditions, as specified in the Restricted Holder Offer. Any Offered Stockholder Shares not sold within such sixty (60) day period shall thereafter again be subject to the requirements of this Section 3.2. 

3.3 Right of Co-Sale. If at any time any Selling Restricted Holder desires to Transfer in any manner any Stockholder Shares
pursuant to the terms of a Restricted Holder Offer received from a Restricted Holder Buyer, then each Major Holder shall have the right (the “Right of Co-Sale”) to require, as a condition to the Transfer, that the Restricted
Holder Buyer purchase from such Major Holder, at the same price per share and on the same terms and conditions as involved in such sale or disposition by the Selling Restricted Holder, that percentage of Stockholder Shares owned by such Major Holder
equal to a fraction: (i) the numerator of which is the number of Stockholder Shares held by such Major Holder; and (ii) the denominator of which is the sum of (a) the aggregate number of Stockholder Shares held by the Major Holders
and (b) the aggregate number of Stockholder Shares then held by the Selling Restricted Holder (such percentage hereinafter referred to as a Major Holder’s “Co-Sale Pro Rata Percentage”). To the extent that a Major
Holder does not exercise its Right of Co-Sale or elects to sell less than its full Co-Sale Pro Rata Percentage pursuant to this Section 3.3, the 

  
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Selling Restricted Holder shall be entitled to sell to the Restricted Holder Buyer, at any time within sixty (60) days of the expiration of the rights granted pursuant to Section 3.2
and this Section 3.3, on the terms set forth in the Restricted Holder Offer, that number Stockholder Shares determined based on the portion of such Stockholder’s Co-Sale Pro Rata Percentage not sold pursuant to this Section 3.3. Any
Offered Stockholder Shares not sold within such sixty (60) day period shall thereafter again be subject to the requirements of this Section 3.3. 
 3.4 Exceptions to Restrictions. The restrictions on a Restricted Holder’s ability to Transfer Stockholder Shares contained in this Section 3 shall not apply to: (i) any Transfer of
Stockholder Shares by a Stockholder to any Permitted Transferee; or (ii) any Transfer of Stockholder Shares to the Company (or any assignee of the Company) pursuant to the terms of a stock restriction or stock repurchase agreement approved by
the Board of Directors which provides for such sale upon the termination of a Stockholder’s service with the Company. In the event of any Transfer pursuant to the foregoing clause “(i)”, the Permitted Transferee of the Stockholder
Shares shall hold the Stockholder Shares so acquired with all the rights conferred by, and subject to all the restrictions imposed by, this Agreement and such Permitted Transferee shall agree in writing to be bound by the terms of this Agreement in
the same capacity as the Stockholder. 
 3.5 Termination. The restrictions on a Restricted Holder’s ability to
Transfer Stockholder Shares contained in this Section 3 shall terminate upon the earlier of: (i) the date of the closing of a firmly underwritten public offering of the Common Stock pursuant to a registration statement filed with the SEC
and declared effective under the Securities Act; or (ii) the date of the closing of a sale, lease, or other disposition of all or substantially all of the Company’s assets or the Company’s merger into or consolidation with any other
corporation or other entity, or any other corporate reorganization, in which the holders of the Company’s outstanding voting stock immediately prior to such transaction own, immediately after such transaction, securities representing less than
fifty percent (50%) of the voting power of the corporation or other entity surviving such transaction; provided, however, that this clause “(ii)” shall not apply to a merger effected exclusively for the purpose of
changing the domicile of the Company. 
 3.6 Additional Holders. As a condition to the issuance by the Company to any
individual or entity (each, an “Additional Holder”) of Stockholder Shares (or rights or options to acquire Stockholder Shares), the Company shall require such Additional Holder to become a party to this Agreement as an
additional “Series C Preferred Holder,” “Series B Preferred Holder,” “Series A Preferred Holder,” “Series A-1 Preferred Holder” or “Common Holder,” as applicable, hereunder via
the execution and delivery to the Company of an Instrument of Accession in the form attached hereto as Exhibit F. 

3.7 “Market Stand-Off” Agreement. Each Stockholder hereby agrees that such Stockholder shall not sell, transfer, make
any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any Stockholder Shares held by such Stockholder (other than those included in the registration) for a
period specified by the representative of the underwriters of Common Stock (or other securities) of the Company not to exceed one hundred eighty (180) days (or such other period as may be requested by the Company or an underwriter to
accommodate regulatory restrictions on (1) the 

  
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publication or other distribution of research reports and (2) analyst recommendations and opinions, including, but not limited to, the restrictions contained in FINRA Rule 2711(f)(4) or NYSE
Rule 472(f)(4), or any successor provisions or amendments thereto), following the effective date of a registration statement of the Company filed under the Securities Act relating to the initial public offering of shares of Common Stock registered
under the Securities Act; provided, however, that all officers and directors of the Company and Stockholders of at least one percent (1%) of the Company’s voting securities enter into similar agreements. The Company may
impose stop-transfer instructions with respect to any Stockholder Shares subject to the foregoing restriction until the end of such one hundred eighty (180) day period (or such other period as may be requested by the Company or an underwriter
to accommodate regulatory restrictions on (1) the publication or other distribution of research reports and (2) analyst recommendations and opinions, including, but not limited to, the restrictions contained in FINRA Rule 2711(f)(4) or
NYSE Rule 472(f)(4), or any successor provisions or amendments thereto). Each Stockholder agrees that any transferee of any Stockholder Shares shall be bound by this Section 3.7. The underwriters of the Company’s stock are intended
third-party beneficiaries of this Section 3.7 and shall have the right, power and authority to enforce the provisions hereof as though they were parties hereto. Any discretionary waiver or termination of the restrictions of any or all of such
agreements by the Company or the underwriters shall apply pro rata to all Stockholders subject to such agreements, based on the number of Stockholder Shares subject to such agreements. 

3.8 Additional Restrictions on Subject Holders. No Subject Holder may Transfer all or any part of the Series C Preferred
Stock or the Series B Preferred Stock held by such Subject Holder prior to December 31, 2014 (the “Trigger Date”), except in the case of a Transfer to a Permitted Transferee; provided, however, that, upon the
Company’s receipt of prior written notice thereof from the Subject Holder, the Board of Directors may approve or reject a proposed Transfer other than to a Permitted Transferee prior to the Trigger Date in its sole discretion. On and after the
Trigger Date (or prior to the Trigger Date with the approval of the Board of Directors pursuant to the immediately preceding sentence), each Subject Holder may Transfer all or any part of its Series C Preferred Stock or Series B Preferred
Stock by following the procedure described in Section 3.2 above; provided, however, that notwithstanding Section 3.2(d) above, in the event that the Company and the Major Holders, on a collective basis, do not elect to purchase all of the
Offered Stockholder Shares pursuant to and within the time periods set forth in Section 3.2, then the provisions of Section 3.2(d) shall not apply but, instead, the Subject Holder may submit a written request to the Board of Directors for
its approval of the Restricted Holder Offer containing the information required to be contained in the Restricted Holder Offer pursuant to Section 3.2(a) above and any other information that may be reasonably required by the Board of Directors
(the “Request”) and thereafter, subject to Section 3.3, may Transfer the remaining Offered Stockholder Shares to the Restricted Holder Buyer only if the Board of Directors has issued to the Subject Holder a written
consent to such Request (the “Consent”) and then only in accordance with the terms of the Consent and of this Agreement. The Board of Directors may withhold or delay such Consent for reasonable business reasons for a period
of up to twelve (12) months following the submission of the Request. Any Consent shall lapse sixty (60) days after the date of the Consent. Any Offered Stockholder Shares not sold within such sixty (60) day period shall thereafter
again by subject to the requirements of this Section 3.8. 

  
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 3.9 Option Upon Involuntary Transfer. Each Subject Holder or its
legal representative shall notify the Company in writing (the “Involuntary Transfer Notice”) promptly upon the occurrence, or any event that may lead to the occurrence, of an involuntary Transfer of all or a portion of its
Stockholder Shares (the “Involuntary Transfer Shares”) by operation of law to any person other than to the Company or the Major Holders in accordance with this Section 3 (including, without limitation, to a
Stockholder’s trustee in bankruptcy, to a purchaser at a creditor’s or court sale, pursuant to the death of a Stockholder, pursuant to a divorce, or to the guardian or conservator of an incompetent or incapacitated Stockholder) (an
“Involuntary Transfer”). The Company shall have the option to purchase all or a portion of the Involuntary Transfer Shares by delivering notice of its election to exercise such option to the person to whom the Involuntary
Transfer Shares were, or are to be, Transferred (the “Involuntary Transferee”) within thirty (30) days after its receipt of the Involuntary Transfer Notice. If the Company does not elect to purchase all of the
Involuntary Transfer Shares, the Company shall, within five (5) days after the expiration of the thirty (30) day notice period specified above, provide each Major Holder with written notice of such election, which notice shall include a
copy of the Involuntary Transfer Notice. Each Major Holder shall then have the right, exercisable within thirty (30) days following receipt of such notice, to purchase up to that number of the Involuntary Transfer Shares that the Company
elected not to purchase (all such remaining shares being referred to as the “Remaining Involuntary Transfer Shares”) equal to the aggregate Remaining Involuntary Transfer Shares multiplied by such Major Holder’s Major
Holder ROFR Pro Rata Share. In the event that a Major Holder does not wish to purchase its full Major Holder ROFR Pro Rata Share, then any Major Holder who has elected to purchase its full Major Holder ROFR Pro Rata Share shall have the right to
purchase, on a pro rata basis with any other Major Holders who so elect, any Remaining Involuntary Transfer Shares not purchased. If any of the foregoing options are timely exercised, the Involuntary Transferee shall sell to the Company or the Major
Holders, as applicable, and the Company or the Major Holders, as applicable, shall purchase from the Involuntary Transferee, such Involuntary Transfer Shares for a purchase price equal to fifty percent (50%) of the Fair Market Value (as defined
below) of a single Involuntary Transfer Share as of the date of the Involuntary Transfer multiplied by the number of Involuntary Transfer Shares being purchased. At its option, the Company or any purchasing Major Holder may elect to purchase
Involuntary Transfer Shares by the delivery of a promissory note in a principal amount equal to the purchase price, which amount shall be payable in full no later than the second (2nd) anniversary of the issuance thereof and may be prepaid in whole or in part at any time at the option of the
maker. For the purposes of this Section 3.9, “Fair Market Value” means the fair market value of each Involuntary Transfer Share, as determined in good faith by the Board of Directors. The Company’s or the Major
Holder’s, as applicable, exercise notice shall specify the time, place and date for settlement of such purchase, which shall be consummated at a closing held within the time period specified above. If the Company and the Major Holders, on a
collective basis, do not elect to purchase all of the Involuntary Transfer Shares pursuant to and within the time periods set forth above, any remaining Involuntary Transfer Shares shall be Transferred to the Involuntary Transferee subject
thereafter to all provisions of this Agreement. 

  
 11 

 4. MISCELLANEOUS. 
 4.1 Legends. 
 (a) Concurrently with the execution of this
Agreement, there shall be imprinted or otherwise placed, on each certificate representing Stockholder Shares, the following restrictive legend (the “Legend”): 

“THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO THE TERMS AND CONDITIONS OF A STOCKHOLDERS’ AGREEMENT WHICH PLACES
CERTAIN RESTRICTIONS ON THE SALE OR TRANSFER OF THE SHARES REPRESENTED HEREBY. ANY PERSON ACCEPTING ANY INTEREST IN SUCH SHARES SHALL BE DEEMED TO AGREE TO AND SHALL BECOME BOUND BY ALL THE PROVISIONS OF SUCH AGREEMENT. A COPY OF SUCH
STOCKHOLDERS’ AGREEMENT WILL BE FURNISHED TO THE RECORD HOLDER OF THIS CERTIFICATE WITHOUT CHARGE UPON WRITTEN REQUEST TO THE COMPANY AT ITS PRINCIPAL PLACE OF BUSINESS.” 

(b) The Company agrees that, during the term of this Agreement, it will not remove, and will not permit to be removed (upon
registration of transfer, reissuance or otherwise), the Legend from any certificate representing Stockholder Shares and will place or cause to be placed the Legend on any new certificate issued to represent Stockholders Shares theretofore
represented by a certificate carrying the Legend. 
 4.2 Successors. The applicable provisions of this Agreement shall be
binding upon the successors in interest to any of the Stockholder Shares. The Company shall not permit the Transfer of any of the Stockholder Shares on its books or issue a new certificate representing any of the Stockholder Shares unless and until
the person to whom such security is to be transferred shall have executed an Instrument of Accession in the form attached hereto as Exhibit F, pursuant to which such person becomes a party to this Agreement and agrees to be bound by all
the provisions hereof. 
 4.3 Specific Performance. The parties acknowledge and agree that it is impossible to measure in
money the damages which will accrue to a party hereto or to their heirs, personal representatives, or assigns by reason of a failure to perform any of the obligations under this Agreement and therefore agree that the terms of this Agreement shall be
specifically enforceable. If any party hereto or its heirs, personal representatives, or assigns institutes any action or proceeding to specifically enforce the provisions hereof, any person against whom such action or proceeding is brought hereby
waives the claim or defense therein that such party or such personal representative has an adequate remedy at law, and such person shall not offer in any such action or proceeding the claim or defense that such remedy at law exists. 

  
 12 

 4.4 Expenses. If any action at law or in equity is necessary to enforce or interpret
the terms of this Agreement, the prevailing party shall be entitled to reasonable attorneys’ fees, costs and necessary disbursements in addition to any other relief to which such party may be entitled. 

4.5 Amendment and Waiver. Any provision of this Agreement may be amended and the observance thereof may be waived (either
generally or in a particular instance and either retroactively or prospectively) only with the written consent of the Company and the Majority Investors. Notwithstanding the foregoing: (i) this Agreement may be amended only with the written
consent of the Company for the sole purpose of including Additional Holders as “Series C Preferred Holders,” “Series B Preferred Holders,” “Series A Preferred Holders,” “Series A-1 Preferred
Holders” or “Common Holders” hereunder; (ii) this Agreement may be amended only with the written consent of the Company for the sole purpose of including additional purchasers of Series C Preferred Stock as
“Series C Preferred Holders” hereunder, additional purchasers of Series B Preferred Stock as “Series B Preferred Holders” hereunder or additional purchasers of Series A Preferred Stock as “Series A
Preferred Holders” hereunder; and (iii) this Agreement may not be amended or terminated and the observance of any term of this Agreement may not be waived with respect to any Stockholder without the written consent of such Stockholder
unless such amendment, termination or waiver applies to all Stockholders in the same fashion. 
 4.6 Notices. All notices
required in connection with this Agreement shall be in writing and shall be deemed effectively given: (i) upon personal delivery to the party to be notified; (ii) when sent by electronic mail or confirmed facsimile, if sent during normal
business hours of the recipient; if not, then on the next business day; (iii) five (5) days after having been sent by registered or certified mail, return receipt requested, postage prepaid; or (iv) one (1) day after deposit with
a nationally recognized overnight courier, specifying next day delivery, with written notification of receipt. All communications shall be sent to the holder appearing on the books of the Company or at such address as such party may designate by ten
(10) days advance written notice to the other parties hereto. 
 4.7 Severability. If one or more provisions of this
Agreement are held by a court of competent jurisdiction to be unenforceable under applicable legal requirements, the parties agree to promptly renegotiate such provision in good faith. In the event that the parties cannot reach a mutually agreeable
and enforceable replacement in writing for such provision, then: (i) such provision shall be excluded from this Agreement; (ii) the balance of this Agreement shall be interpreted as if such provision were so excluded; and (iii) the
balance of this Agreement shall be enforceable in accordance with its terms. 
 4.8 Governing Law. This Agreement shall
be governed by and construed in accordance with the General Corporation Law of the State of Delaware without reference to its principles of conflict of laws. 
 4.9 Entire Agreement. This Agreement, together with the exhibits and schedules hereto, constitutes the entire agreement among the parties, and no party shall be liable or bound to any other party
in any manner by any warranties, representations, or covenants except as specifically set forth herein or therein. 

  
 13 

 4.10 Counterparts; Execution by Facsimile. This Agreement may be executed in two or
more counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. Delivery of an executed counterpart of this Agreement by facsimile (or similar electronic means) shall be equally
as effective as delivery of an original executed counterpart of this Agreement. 
 [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

  
 14 

 IN WITNESS WHEREOF, the parties hereto
have executed this SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT as of the date first written above. 

 

			
	COMPANY:
	
	ARATANA THERAPEUTICS, INC.
	
	 /s/ Steven St. Peter

	Steven St. Peter
	Chief Executive Officer
		
	Address:	 	 1901 Olathe Boulevard
 Kansas
City, KS 66103

	
	STOCKHOLDER:
	
	AVALON VENTURES IX, L.P.
		
	By:	 	Avalon Ventures IX GP, LLC
	Its:	 	General Partner
	
	 /s/ Jay Lichter

	Name:	 	Jay Lichter
	Title:	 	Managing Member
		
	Address:	 	1134 Kline Street
		 	La Jolla, CA 92037
	
	STOCKHOLDER:
	
	MPM BIOVENTURES V, L.P.
		
	By:	 	MPM BioVentures V GP LLC
	Its:	 	General Partner
		
	By:	 	MPM BioVentures V LLC
	Its:	 	Managing Member
	
	 /s/ John Vander Vort

	Name:	 	John Vander Vort
	Title:	 	Member
		
	Address:	 	200 Clarendon St. 54F
		 	Boston, MA 02116
	
	MPM ASSET MANAGEMENT INVESTORS
	BV5 LLC
		
	By:	 	MPM BioVentures V LLC
	Its:	 	Manager
	
	 /s/ John Vander Vort

	Name:	 	John Vander Vort
	Title:	 	Member
		
	Address:	 	200 Clarendon St. 54F
		 	Boston, MA 02116

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	 MIDPOINT FOOD & AG FUND, LP

	(entity name if applicable)
		
	By:	 	 /s/ R. Meeusen

	(signature)
		
	Print Name:	 	 R. Meeusen

	Title:	 	 Partner

	(if applicable)
		
	Address:	 	11550 N. Meridian
		 	Carmel, IN 46033
	
	STOCKHOLDER:
	
	 MIDPOINT FOOD & AG

	 CO-INVESTMENT FUND, LP

	(entity name if applicable)
		
	By:	 	 /s/ R. Meeusen

	(signature)
		
	Print Name:	 	 R. Meeusen

	Title:	 	 Partner

	(if applicable)
		
	Address:	 	11550 N. Meridian St.
		 	Carmel, IN 46032
	
	STOCKHOLDER:
	
	 EWING MARION KAUFFMAN

	 FOUNDATION

	(entity name if applicable)
		
	By:	 	 /s/ Kristen Bechard

	(signature)
		
	Print Name:	 	 Kristen Bechard

	Title:	 	 Controller

	(if applicable)
		
	Address:	 	4801 Rockhill Road
		 	Kansas City, MO 64110

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	 HALL FAMILY FOUNDATION

	(entity name if applicable)
		
	By:	 	 /s/ John A. MacDonald

	(signature)
		
	Print Name:	 	 John A. MacDonald

	Title:	 	 VP &Treasurer

	(if applicable)
		
	Address:	 	P.O. Box 419580
		 	Maildrop 323
		 	Kansas City, MO 64141
	
	STOCKHOLDER:
	
	 MIDDLELAND AG FUND, LP

	(entity name if applicable)
		
	By:	 	 /s/ Brian Mixe

	(signature)
		
	Print Name:	 	 Brian Mixe

	Title:	 	 Manager, Middleland AG LLC, its

general partner

	(if applicable)
		
	Address:	 	888 16th St.
		 	Suite 800
		 	Washington, DC 20006

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	 MID-AMERICA ANGELS INVESTMENTS,

LLC

	(entity name if applicable)
		
	By:	 	 /s/ Joel Wiggins

	(signature)
		
	Print Name:	 	 Joel Wiggins

	Title:	 	 Executive Manager

	(if applicable)
		
	Address:	 	8527 Bluejacket Street
		 	Lenexa, KS 66214
		 	PH: 913.438.2282
	
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ William Gautreaux

	(signature)
		
	Print Name:	 	 William Gautreaux

	Title:	 	  

	(if applicable)
		
	Address:	 	200 W 54th St.
		 	Kansas City, MO 64112
	
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Irv Hockaday

	(signature)
		
	Print Name:	 	 Irv Hockaday

	Title:	 	  

	(if applicable)
		
	Address:	 	2600 Grand Ave.
		 	Suite 450
		 	Kansas City, MO 64108

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	 GRASSMERE KANSAS ANGEL

INVESTMENTS, LLC

	(entity name if applicable)
		
	By:	 	 /s/ Peter C. Brown

	(signature)
		
	Print Name:	 	 Peter C. Brown

	Title:	 	 Chairman

	(if applicable)
		
	Address:	 	801 W. 47th St., Suite 400
		 	Kansas City, MO 64112
	
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ David Frantze

	(signature)
		
	Print Name:	 	 David Frantze

	Title:	 	  

	(if applicable)
		
	Address:	 	2200 W. 125th St.
		 	Leawood, KS 66209
	
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Stephen A. Lightstone

	(signature)
		
	Print Name:	 	 Stephen A. Lightstone

	Title:	 	  

	(if applicable)
		
	Address:	 	4935 Central St.
		 	Kansas City, MO 64112

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Michael A. Driscoll

	(signature)
		
	Print Name:	 	 Michael A. Driscoll

	Title:	 	  

	(if applicable)
		
	Address:	 	823 Woodland Ave
		 	Oradell, NJ 07649
	
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Chris McGrath

	(signature)
		
	Print Name:	 	 Chris McGrath

	Title:	 	  

	(if applicable)
		
	Address:	 	5078 Seashell Place
		 	San Diego, CA 92130
	
	STOCKHOLDER:
	
	 LIMIT &CO

	(entity name if applicable)
		
	By:	 	 /s/ John A. MacDonald

	(signature)
		
	Print Name:	 	 John A. MacDonald

	Title:	 	 General Partner

	(if applicable)
		
	Address:	 	Chinquapin Trust Co.
		 	P.O. Box 419580, Mail Drop 323
		 	Kansas City, MO 64141

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	 VIE VENTURE LLC

	(entity name if applicable)
		
	By:	 	 /s/ Steven St. Peter

	(signature)
		
	Print Name:	 	 Steven St. Peter

	Title:	 	 Member

	(if applicable)
		
	Address:	 	1901 Olathe Blvd
		 	Kansas City, KS 66103
	
	STOCKHOLDER:
	
	 THE SANCHEZ FAMILY TRUST,

MARCH 31, 2011, CARL SANCHEZ AND

ANGELA ROMERO SANCHEZ,
 TRUSTEES

	(entity name if applicable)
		
	By:	 	 /s/ Carl Sanchez

	(signature)
		
	Print Name:	 	 Carl Sanchez

	Title:	 	 Trustee

	(if applicable)
		
	Address:	 	1318 Summit Avenue
		 	Cardiff, CA 92007
	
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Robert F. Willamson

	(signature)
		
	Print Name:	 	 Robert F. Willamson

	Title:	 	  

	(if applicable)
		
	Address:	 	140 La Salle Ave
		 	Piedmont, CA 94610

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Eric I. Richman

	(signature)
		
	Print Name:	 	 Eric I. Richman

	Title:	 	  

	(if applicable)
		
	Address:	 	9740 Sorrel Ave
		 	Potomac, MD 20854
	
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ William F. Hartfiel III

	(signature)
		
	Print Name:	 	 William F. Hartfiel III

	Title:	 	  

	(if applicable)
		
	Address:	 	2732 Thomas Ave South
		 	Minneapolis, MN 55416
	
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Richard A. Sapp

	(signature)
		
	Print Name:	 	 Richard A. Sapp

	Title:	 	  

	(if applicable)
		
	Address:	 	PO Box 1514
		 	Rancho Santa Fe, CA 92067-1514

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Sanford J. Madigan

	(signature)
		
	Print Name:	 	 Sanford J. Madigan

	Title:	 	  

	(if applicable)
		
	Address:	 	12577 Kingspine Ave
		 	San Diego, CA 92131
	
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Gary William Pace

	(signature)
		
	Print Name:	 	 Gary William Pace

	Title:	 	  

	(if applicable)
		
	Address:	 	1405 Inspiration Dr.
		 	La Jolla, CA 92037
	
	STOCKHOLDER:
	
	 CURTIS A. KRIZEK REVOCABLE

TRUST, UTA DTD 12/17/98

	(entity name if applicable)
		
	By:	 	 /s/ Curtis A. Krizek

	(signature)
		
	Print Name:	 	 Curtis A. Krizek

	Title:	 	 Trustee

	(if applicable)
		
	Address:	 	4900 Main Street, Suite 700
		 	Kansas City, MO 64112

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Andrew S. Klocke

	(signature)
		
	Print Name:	 	 Andrew S. Klocke

	Title:	 	  

	(if applicable)
		
	Address:	 	8016 Cherokee Lane
		 	Leawood, KS 66206
	
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ John Neil

	(signature)
		
	Print Name:	 	 John Neil

	Title:	 	  

	(if applicable)
		
	Address:	 	7445 East Butler Drive
		 	Scottsdale, AZ 85258
	
	STOCKHOLDER:
	
	 MVA CAPITAL GROUP, LLC

	(entity name if applicable)
		
	By:	 	 /s/ Patricia L. Brasted

	(signature)
		
	Print Name:	 	 Patricia L. Brasted

	Title:	 	 Managing Member

	(if applicable)
		
	Address:	 	7829 E. Rockhill Rd. #307
		 	Wichita, KS 67206

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	 KANSAS CENTER FOR

	 ENTREPRENEURSHIP

	(entity name if applicable)
		
	By:	 	 /s/ Patricia L. Brasted

	(signature)
		
	Print Name:	 	 Patricia L. Brasted

	Title:	 	 President and CEO of Wichita

		 	 Technology Corporation

	(if applicable)
		
	Address:	 	7829 E. Rockhill Rd., Suite 307
		 	Wichita, KS 67206
	
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ David K. Rosen

	(signature)
		
	Print Name:	 	 David K. Rosen

	Title:	 	  

	(if applicable)
		
	Address:	 	85 Kendal Court
		 	Guilford, CT 06437
	
	STOCKHOLDER:
	
	STEVEN ST. PETER
	
	 /s/ Steven St. Peter

		
	Address:	 	43 Union Park #2
		 	Boston, MA 02118

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Linda Rhodes

	(signature)
		
	Print Name:	 	 Linda Rhodes

	Title:	 	 Chief Scientific Officer

	(if applicable)
		
	Address:	 	3 White Birch Ln
		 	Holmdel, NJ 07733

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

 
			
	STOCKHOLDER:
	
	KANSAS BIOSCIENCE AUTHORITY
	
	 /s/ Duane Cantrell

	Name:	 	Duane Cantrell
	Title:	 	President and CEO
		
	 Address:
	 	 10900 S. Clay Blair Blvd.

Olathe, KS 66061

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT] 

 
			
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Paul DeBruce

	(signature)
		
	Print Name:	 	 Paul DeBruce

	Title:	 	  

	(if applicable)
		
	Address:	 	411 Nichols Road, Suite 217
		 	Kansas City, MO 64112

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT] 

 
			
	STOCKHOLDER:
	
	 UMB BANK, N.A., AS CUSTODIAN FOR

	 THE SHEILA KEMPER DIETRICH IRA

	(entity name if applicable)
		
	By:	 	 /s/ Robert Paredes

	(signature)
		
	Print Name:	 	 ROBERT PAREDES

	Title:	 	 V.P. / SR. TRUST ADVISOR

		 	(if applicable)
		
	 Address:
	 	1010 GRAND BOULEVARD
		 	KANSAS CITY, MO 64106

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT] 

 
			
	STOCKHOLDER:
	
	 Leerink Swann Holdings, LLC

	(entity name if applicable)
		
	By	 	 /s/ Timothy A. G. Gerhold

	(signature)
		
	Print Name:	 	 TIMOTHY A. G. GERHOLD

	Title:	 	 GENERAL COUNSEL

	(if applicable)
		
	Address:	 	1 Federal St. 37th Floor
		 	Boston, MA 02110

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT] 

			
	STOCKHOLDER:
	
	 Leerink Swann Co-Investment Fund, LLC

	(entity name if applicable)
		
	By:	 	 /s/ Jeffrey A. Leerink

	(signature)
		
	Print Name:	 	 Jeffrey A. Leerink

	Title:	 	 Manager

	(if applicable)
		
	Address:	 	
	 1 Federal St., 37th Floor

	 Boston, MA 02110

	

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT] 

			
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Louise Mawhinney

	(signature)
		
	Print Name:	 	 LOUISE MAWHINNEY

	Title:	 	  

	(if applicable)
		
	Address:	 	22 FROST LANE
		 	SUDBURY, MA 01776

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT] 

 
			
	STOCKHOLDER:
	
	Christena A. Gautreaux Trust 2004
	(entity name if applicable)
		
	By:	 	 /s/ C Gautreaux

	(signature)
		
	Print Name:	 	 Christena Gautreaux

	Title:	 	 Trustee

	(if applicable)
		
	Address:	 	200 West 54th St.
		 	KANSAS City, MO 64112

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT] 

 
			
	STOCKHOLDER:
	
	  
	(entity name if applicable)
		
	By:	 	 /s/ Erick Lucera

	(signature)
		
	Print Name:	 	 Erick Lucera

	Title:	 	      

	(if applicable)
		
	Address:	 	138 Thistle Road
		 	North Andover, MA 01845

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT] 

 
			
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Julia Stephanus

	(signature)
		
	Print Name:	 	 Julia Stephanus

	Title:	 	 Chief Commercial Officer Aratana Therapeutics

		 	(if applicable)
		
	Address:	 	21 Talmadge Lane
		 	Basking Ridge, NJ 07920

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT] 

 
			
	STOCKHOLDER:
	
	  

	(entity name if applicable)
		
	By:	 	 /s/ Thomas L. Shoaf

	(signature)
		
	Print Name:	 	 Thomas L. Shoaf

	Title:	 	  

	(if applicable)
		
	Address:	 	4224 Beverly Drive
		 	Dallas TX 75205

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDER’S AGREEMENT] 

	
	STOCKHOLDER:
	
	  

	(entity name if applicable)

 
			
		
	By	 	 /s/ Fulton Murray III

	(signature)
		
	Print Name:	 	 John Fulton Murray III

	Title:	 	  

	(if applicable)
		
	Address:	 	7 Westover Rd
		 	Ft Worth TX 76107

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT] 

 EXHIBIT A 
 SERIES C PREFERRED HOLDERS 
 Avalon Ventures IX, L.P. 

MPM Bio Ventures V, L.P. 
 MPM Asset Management
Investors BV5 LLC 
 MidPoint Food & Ag Fund, LP 
 MidPoint Food & Ag Co-Investment Fund, LP 
 Hall Family Foundation 

Middleland AG Fund, LP 
 Mid-America Angels
Investments, LLC 
 William Gautreaux 

Irv Hockaday 
 Grassmere Kansas Angel
Investments, LLC 
 David W. Frantze 

Stephen A. Lightstone 
 Michael A. Driscoll

 Christopher H. McGrath 
 Limit &
Co. 
 Vie Venture LLC 
 The Sanchez
Family Trust, March 31, 2011, Carl Sanchez and Angela Romero Sanchez, Trustees 
 Robert F. Williamson 

Eric I. Richman 
 William F. Hartfiel III

 Richard A. Sapp 
 Sanford J. Madigan

 Gary William Pace 

 Curtis A. Krizek Revocable Trust UTA Dtd 12/17/98 
 Andrew S. Klocke 
 John Neil 
 Ewing Marion Kauffman Foundation 
 Kansas Bioscience Authority 

Paul DeBruce 
 UMB Bank, N.A., as Custodian for
the Sheila Kemper Dietrich IRA 
 Leerink Swann Holdings, LLC 
 Leerink Swann Co-Investment Fund, LLC 
 Louise Mawhinney 

Christena A. Gautreaux Trust 2004 
 Erick Lucera

 Julia Stephanus 
 Thomas L. Shoaf

 John Fulton Murray III 

 EXHIBIT B 

SERIES B PREFERRED HOLDERS 
 Avalon Ventures IX, L.P. 
 MPM BioVentures V, L.P. 

MPM Asset Management Investors BV5 LLC 

MidPoint Food & Ag Fund, LP 
 MidPoint
Food & Ag Co-Investment Fund, LP 
 Kansas Bioscience Authority 
 Ewing Marion Kauffman Foundation 
 Hall Family Foundation 

Middleland AG Fund, LP 
 Mid-America
Angels Investments, LLC 
 MVA Capital Group LLC 
 Paul DeBruce 
 Christena Gautreaux 
 Irv Hockaday 
 Grassmere Kansas Angel Investments, LLC 

Brian N. Kaufman 
 David W. Frantze

 The Maichen Family Trust Dated 7/13/99 
 Stephen A. Lightstone 
 John Neil 
 Michael A. Driscoll 
 Sheila Kemper Dietrich IRA 

Christopher H. McGrath 
 Kansas Center for
Entrepreneurship, Inc. 

 EXHIBIT C 

SERIES A PREFERRED HOLDERS 
 Avalon Ventures IX, L.P. 
 MPM BioVentures V, L.P. 

MPM Asset Management Investors BV5 LLC 

MidPoint Food & Ag Fund, LP 
 MidPoint
Food & Ag Co-Investment Fund, LP 
 Kansas Bioscience Authority 

 EXHIBIT D 

SERIES A-1 PREFERRED HOLDERS 
 RaQualia Pharma Inc. 

 EXHIBIT E 
 COMMON HOLDERS 
 David K. Rosen 
 MPM BioVentures V, L.P. 
 MPM Asset Management Investors BV5 LLC 

Steven St. Peter 
 Louis Mawhinney 

Linda Rhodes 
 Bill Zollers 

Lesley Rausch-Derra 
 Michele Gallucci

 Rose Ann Potter 
 Jim Branch

 Julia Stephanus 

 EXHIBIT F 

INSTRUMENT OF ACCESSION 
 The undersigned,                     , as a condition precedent to becoming the owner or holder of
record of                     (            ) shares of
            stock of Aratana Therapeutics, Inc., a Delaware corporation (the “Company”), hereby agrees to become a
“                    Holder” under that certain Second Amended and Restated Stockholders’ Agreement, dated as of December 28,
2012 (the “Stockholders’ Agreement”), by and among the Company and the parties named therein. This Instrument of Accession shall take effect and shall become an integral part of, and the undersigned shall become a party
to and bound by, the Stockholders’ Agreement immediately upon execution and delivery to the Company of this Instrument. 

IN WITNESS WHEREOF, this INSTRUMENT OF ACCESSION has been duly executed by or on behalf of the undersigned, as a sealed instrument under
the laws of the State of Delaware, as of the date below written. 
  

			
	Signature:
	
	  

		
	(Print Name)	 	  

 

			
	
	Address:
	
	  

	
	  

		
	Date:	 	  

	
	Accepted:
	
	ARATANA THERAPEUTICS, INC.
		
	By:	 	  

		 	Name:
		 	Title:
		
	Date:	 	  

 AMENDMENT NO. 1 TO 

SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT 
 This Amendment No. l to Second Amended and Restated Stockholders’ Agreement, dated as of May 22, 2013 (this “Amendment”), by and among Aratana Therapeutics, Inc., a Delaware
corporation (the “Company”), Avalon Ventures IX, L.P. (“Avalon”), MPM BioVentures V, L.P. (“MPM,” and together with Avalon, the “Majority Investors”), and the other stockholders of
the Company set forth on the signature pages to the Agreement (as defined below) (together with the Majority Investors, the “Investors”). Terms used but not defined herein shall have the meanings assigned to them in that certain
Second Amended and Restated Stockholders’ Agreement, dated as of December 28, 2012 (the “Agreement”), by and among the Company and the Investors. 
 WHEREAS, the Company plans to issue and sell newly issued shares of its common stock in an initial public offering to be registered under the Securities Act of 1933, as amended, on a Registration
Statement on Form S-1 (No. 333-187372) previously filed with the Securities and Exchange Commission (the “Offering”). 
 WHEREAS, the Company and the Investors desire to amend certain provisions of the Agreement in connection with the Offering, as set forth below. 

WHEREAS, Section 4.5 of the Agreement provides that any term of the Agreement may be amended and the observance of any term of the
Agreement may be waived (either generally or in a particular instance and either retroactively or prospectively), only with the written consent of the Company and the Majority Investors. 

NOW, THEREFORE, in consideration of the promises and the mutual covenants and agreements contained herein and in the Agreement, the
parties hereby agree as follows: 
 Section 1. Amendment. 

(a) Section 3.5 of the Agreement is hereby amended and restated in its entirety to read as follows: 

“Termination. The restrictions on a Restricted Holder’s ability to Transfer Stockholder Shares contained
in this Section 3 shall terminate upon the earlier of: (i) the date of the closing of a firmly underwritten public offering of the Common Stock pursuant to a registration statement filed with the SEC and declared effective under the
Securities Act; or (ii) the date of the closing of a sale, lease, or other disposition of all or substantially all of the Company’s assets or the Company’s merger into or consolidation with any other corporation or other entity, or
any other corporate reorganization, in which the holders of the Company’s outstanding voting stock immediately prior to such transaction own, immediately after such transaction, securities representing less than fifty percent (50%) of the
voting power of the corporation or other entity surviving such transaction; provided, however, that this clause “(ii)” shall not apply to a merger effected exclusively for the purpose of changing the domicile of the Company. The
restrictions contained in Sections 3.8 and 3.9 shall terminate upon the earlier of: (i) the date of the closing of a firmly underwritten public offering of the Common Stock pursuant to a registration statement filed with the SEC and declared
effective under the Securities Act; or (ii) the date of the closing of a sale, lease, or other disposition of all or substantially all of the Company’s assets or the Company’s merger into or consolidation with any other corporation or
other entity, or any other corporate reorganization, in which the holders of 

 
the Company’s outstanding voting stock immediately prior to such transaction own, immediately after such transaction, securities representing less than fifty percent (50%) of the voting
power of the corporation or other entity surviving such transaction; provided, however, that this clause “(ii)” shall not apply to a merger effected exclusively for the purpose of changing the domicile of the Company.” 

Section 2. Governing Law. This Amendment will be governed by and construed in accordance with the laws of the State of
Delaware without regard to any choice of law or conflict of law provision or rule that would cause the application of the laws of any other jurisdiction. 
 Section 3. Counterparts. This Amendment may be executed in two or more counterparts, each of which will be deemed an original but all of which together will constitute one and the same
instrument. All such counterparts will be deemed an original, will be construed together and will constitute one and the same instrument. 
 Section 4. Headings. The headings in this Amendment are for reference purposes only and will not in any way affect the meaning or interpretation of this Amendment. 

Section 5. Prior Agreements. This Amendment and the other agreements contemplated hereby constitute the entire agreement
between the parties concerning the subject matter hereof and supersedes any prior representations, understandings or agreements. There are no representations, warranties, agreements, conditions or covenants, of any nature whatsoever (whether express
or implied, written or oral) between the parties hereto with respect to such subject matter except as expressly set forth herein and in the other agreements contemplated hereby. 

Section 6. Severability. In the event that any one or more of the provisions contained herein, or the application thereof in
any circumstances, is held invalid, illegal or unenforceable in any respect for any reason, the validity, legality and enforceability of any such provision in every other respect and of the remaining provisions contained herein will not be in any
way impaired thereby, it being intended that all of the rights and privileges of the parties hereto will be enforceable to the fullest extent permitted by law. 
 Section 7. No Further Effect. Except as explicitly modified by this Amendment, the Agreement shall remain in full force and effect in accordance with its terms. 

[Signature Pages Follow] 

  
 2 

 IN WITNESS WHEREOF, the parties have duly executed this Amendment as of the date first above
written. 
  

			
	ARATANA THERAPEUTICS, INC.
		
	By:	 	/s/ Steven St. Peter
		 	Name: Steven St. Peter
		 	Title: President and Chief Executive Officer

  

			
	AVALON VENTURES IX, L.P.
		
	By:	 	AVALON VENTURES IX GP, LLC
	Its:	 	General Partner
		
	By:	 	/s/ Jay Lichter
		 	Name: Jay Lichter
		 	Title: Managing Member

  

			
	MPM BIOVENTURES V, L.P.
		
	By:	 	MPM BIOVENTURES V GP LLC
	Its:	 	General Partner
		
	By:	 	MPM BIOVENTURES V LLC
	Its:	 	Managing Member
		
	By:	 	/s/ John Vander Vort
		 	Name: John Vander Vort
		 	Title: Member

  

			
	MPM ASSET MANAGEMENT INVESTORS BV5 LLC
		
	By:	 	MPM BIOVENTURES V LLC
	Its:	 	Manager
		
	By:	 	/s/ John Vander Vort
		 	Name: John Vander Vort
		 	Title: Member

 Signature Page to Amendment No. 1 to Second Amended and Restated Stockholders’
Agreement 

 
			
	MIDPOINT FOOD AND AG FUND, LP
		
	By:	 	/s/ Ron Meeusen
		 	Name: Ron Meeusen
		 	Title: Partner

  

			
	MIDPOINT FOOD AND AG CO-INVESTMENT FUND, LP
		
	By:	 	/s/ Ron Meeusen
		 	Name: Ron Meeusen
		 	Title: Partner

  

			
	VIE VENTURE LLC
		
	By:	 	/s/ Steven St. Peter
		 	Name: Steven St. Peter
		 	Title: Member

 Signature Page to Amendment No. 1 to Second Amended and Restated Stockholders’
AgreementEX-10.4

 Exhibit 10.4 
 ARATANA THERAPEUTICS, INC. 
 EMPLOYMENT AGREEMENT 

This EMPLOYMENT AGREEMENT (this “Agreement”) is made and
entered into as of September 6, 2012 (the “Effective Date”) by and between ARATANA THERAPEUTICS, INC. (the “Company”) and Steven St. Peter
(the “Executive”). The Company and the Executive are hereinafter collectively referred to as the “Parties”, and individually referred to as a “Party”. 

RECITALS 
 A. As of the date of this Agreement, the Executive is engaged as a consultant to the Company pursuant to the terms of that certain Consulting Agreement, dated as of May 18, 2012 (the
“Consulting Agreement”), by and between the Executive and the Company. 
 B. The Company desires
to employ the Executive to serve as its President and Chief Executive Officer, subject to the terms and conditions set forth in this Agreement, effective as of the Effective Date. 

C. The Executive desires to accept such employment by the Company, subject to the terms and conditions set forth in this
Agreement, effective as of the Effective Date. 
 AGREEMENT 

In consideration of the foregoing Recitals and the mutual promises and covenants herein contained, and for other good and valuable
consideration, the Parties, intending to be legally bound, agree as follows: 
 1. EMPLOYMENT. 

1.1 Termination of Consulting Agreement. Effective as of the Effective Date and subject to the commencement of employment
hereunder, the Consulting Agreement shall be terminated and be of no further force and effect, and neither of the Parties thereto shall have any remaining rights or obligations thereunder, except with respect to such provisions that survive the
termination of the Consulting Agreement as set forth in Section 9.4 thereof. For purposes of the option (the “Consulting Option”) to purchase shares of the Company’s common stock (the “Common
Stock”) granted to the Executive pursuant to the Stock Option Agreement, dated as of August 2, 2012 (the “Existing Option Agreement”), by and between the Company and the Executive, as of the Effective Date:
(i) subject to this Section 1.1, the Executive’s Continuous Service (as defined in Company’s 2010 Equity Incentive Plan (the “Plan”)) shall be deemed to have ended; (ii) notwithstanding anything to
the contrary set forth in the Plan or the Existing Option Agreement, the Executive will be entitled to exercise, in accordance with the terms of the Plan and the Existing Option Agreement, the Consulting Option with respect to 125,000 shares of
Common Stock underlying the Consulting Option, which shares shall be deemed to have vested as of the Effective Date; and (iii) the Consulting Option shall terminate with respect to the remaining 75,000 shares of Common Stock underlying the
Consulting Option. 
 1.2 Offer and Acceptance of Employment. The Company hereby agrees to employ the Executive, and the
Executive hereby accepts such employment with the Company, in each case effective as of the Effective Date and otherwise subject to the terms and conditions set forth in this Agreement. 

 1.3 Title. Effective as of the Effective Date, the Executive’s position shall be
designated as a Founder, President and Chief Executive Officer, subject to the terms and conditions set forth in this Agreement. 
 1.4 Term. The term of this Agreement shall begin on the Effective Date and shall continue until terminated pursuant to Section 4 herein (the “Term”); provided,
however, that the Parties expressly acknowledge and agree that the Executive’s employment with the Company is at will and may, subject to the provisions of Section 4, be terminated by the Company or by the Executive at any time for
any reason or for no reason. 
 1.5 Duties. During the Term, the Executive shall perform such services as are normally
associated with the position of President and Chief Executive Officer and shall report directly to the Company’s board of directors (the “Board”). The Executive shall also continue to serve as a member of the Board;
provided, however, that the Executive shall, except as may be otherwise mutually agreed by the Parties, immediately resign from the Board in the event of the termination of his employment with the Company pursuant to this Agreement for
any reason. 
 1.6 Policies and Practices. The employment relationship between the Parties shall be governed by this
Agreement and by the policies and practices established by the Company and the Board. In the event that the terms of this Agreement differ from or are in conflict with the Company’s policies or practices as in effect from time to time, this
Agreement shall control. 
 1.7 Location. Unless the Parties otherwise agree in writing, during the Term the Executive
shall perform the services the Executive is required to perform pursuant to this Agreement at a business office established by the Company following the date of this Agreement that is located within fifty (50) miles of the Executive’s
residence on the Effective Date as set forth on the signature page hereto; provided, however, that the Company may from time to time require the Executive to travel temporarily to other locations (including Kansas City) in connection
with the Company’s business; and provided further that the Executive may elect in his sole discretion to perform the services the Executive is required to perform pursuant to this Agreement at any other business office established
by the Company (including in Kansas City). 
 2. DISCHARGE OF DUTIES;
NONCOMPETITION. 
 2.1 Duties. During the Executive’s employment by the Company, the Executive
shall devote the substantial majority of the Executive’s business time and sufficient time to the discharge of the Executive’s duties under this Agreement; provided, however, that, subject to Section 2.2 and
Section 2.3 and provided that such activities do not materially interfere with the performance of the Executive’s duties under this Agreement, the Executive may participate in the activities listed on Exhibit A attached hereto,
as well as charitable, community or civic activities and any other activities that may be disclosed by the Executive in writing in advance to, and approved by, the Board after the date hereof. 

  
 2 

 2.2 Covenant Not to Compete. The Executive acknowledges and agrees that the business
of the Company is nationwide in scope. The Executive further acknowledges and agrees that during the course of his employment with the Company he will learn confidential information relating to the Company and its business and business strategies
and will develop business relationships on behalf of the Company at the Company’s expense. The Executive acknowledges and agrees that if he were to divert this information and the relationships to a competitor, the Company would suffer
irreparable harm to its business and goodwill in an amount that cannot be readily quantified. Accordingly, the Executive agrees that during the Term and for nine (9) months following the termination of his employment for any reason, the
Executive shall not engage in competition with the Company and/or any of its Affiliates (as defined below), either directly or indirectly, in any manner or capacity, as adviser, principal, agent, Affiliate, promoter, partner, officer, director,
employee, stockholder, owner, co-owner, consultant or member of any association or otherwise, in any phase of the business of developing, licensing, manufacturing, distributing or marketing of products or services that are in the same Field of Use
(as defined below) or which are otherwise in competition with the actual or reasonably anticipated products or services of the Company at the time of his separation from the Company, except with the prior written consent of the Board. For purposes
of this Agreement, “Field of Use” means the development of companion animal therapeutic products. The Executive acknowledges and agrees that because of the nationwide scope of the Company’s business, this restriction
shall be nationwide. For purposes of this Agreement, “Affiliate” means, with respect to any specific entity, any other entity that, directly or indirectly, through one or more intermediaries, controls, is controlled by or is
under common control with such specified entity. Ownership by the Executive in professionally managed funds over which the Executive does not have control or discretion in investment decisions or as a passive investment of less than two percent
(2%) of the outstanding shares of capital stock of any corporation with one or more classes of its capital stock listed on a national securities exchange or publicly traded on a national securities exchange or in the over-the-counter market
shall not constitute a breach of this Section 2.2. 
 2.3 Covenant Not To Solicit. The Executive agrees that during
the Term and for one (1) year following the termination of his employment for any reason, he shall not, directly or indirectly, solicit or recruit any employees of the Company to terminate their work for the Company or to perform services in
competition with the Company. 
 3. COMPENSATION OF THE
EXECUTIVE. 
 3.1 Base Salary. The Company shall pay the Executive a base salary at the rate of Four
Hundred Twenty-Five Thousand U.S. Dollars ($425,000.00) per year (the “Base Salary”), less payroll deductions and all required withholdings, payable in regular periodic payments in accordance with the Company’s normal
payroll practices. The Base Salary shall be prorated for any partial year of employment on the basis of a 365-day fiscal year. The Base Salary shall be subject to review and adjustment from time to time by and at the sole discretion of the Board
(excluding the Executive) or any committee thereof. 
 3.2 Annual Bonus. The Executive will be eligible to receive an
annual cash bonus (the “Bonus”) payment of up to thirty-five percent (35%) of the Base Salary with respect to each calendar year, subject to the Executive’s continued employment with the Company as of

  
 3 

 
the end of such calendar year and contingent upon successful achievement of corporate objectives established from year to year by the Board (excluding the Executive). Any Bonus pursuant to this
Section 3.2 shall be paid as promptly as practicable following the end of the applicable calendar year, but not later than March 15th of the following calendar year. 
 3.3 Equity Compensation. 
 3.3.1 Stock Option. 

(i) Subject to Board approval (excluding the Executive), promptly following the Effective Date, the Company shall grant the
Executive a nonqualified stock option (the “Stock Option”) pursuant to the Plan to purchase up to that number of shares of Common Stock as is equal to approximately 1.333% (or 288,556) of all shares of Common Stock that are:
(x) outstanding; (y) issuable upon conversion of outstanding convertible securities or upon exercise of outstanding options and warrants; or (z) reserved for issuance pursuant to the Plan (the “Fully Diluted
CSEs”) on the date of grant, at the Common Stock’s fair market value as determined in good faith by the Board (excluding the Executive) as of the date of such grant. 

(ii) The Stock Option shall be granted subject to the terms and conditions of the Plan and a written option agreement to be
entered into by the Company and the Executive (the “New Option Agreement”). The New Option Agreement shall provide, among other things, that all shares of Common Stock underlying the Stock Option shall vest: (x) as to
1/4th of the underlying shares, upon the first (1st) anniversary of July 1, 2012 (the “Vesting Commencement Date”); and (y) as to the remaining underlying shares, in equal monthly installments over the
following thirty-six (36) months such that all shares shall be vested as of the fourth (4th) anniversary of the Vesting Commencement Date, subject to the Executive’s continued employment with the Company on each such vesting date;
provided, however, that: (a) the Stock Option shall be subject to accelerated vesting as provided in Section 3.3.4, Section 4.5.1 and Section 4.5.3(iii); and (b) “early exercise” of the Stock Option
shall be permitted pursuant to the terms of the Plan and the New Option Agreement. 
 3.3.2 First Restricted Stock
Award. 
 (i) Subject to Board approval (excluding the Executive), promptly following the Effective Date, the
Company shall grant the Executive an award of restricted stock (the “First Restricted Stock Award”) pursuant to the Plan for that number of shares of Common Stock as is equal to approximately 1.333% (or 288,556 shares) of the
Company’s Fully Diluted CSEs on the date of grant. 
 (ii) The First Restricted Stock Award shall be granted
subject to the terms and conditions of the Plan and a written award agreement to be entered into by the Company and the Executive (the “First Restricted Stock Award Agreement”). The First Restricted Stock Award Agreement
shall provide, among other things, that all shares of Common Stock underlying the First Restricted Stock Award shall vest: (x) as to fifty percent (50%) of the underlying shares, upon the first (1st) anniversary of the Vesting
Commencement Date; and (y) as to the remaining underlying shares, in equal monthly installments over the following twelve (12) months, such that all shares shall be vested as of the second (2nd) anniversary of the

  
 4 

 
Vesting Commencement Date, subject to the Executive’s continued employment with the Company on each such vesting date; provided, however, that the First Restricted Stock Award
shall be further subject to accelerated vesting as provided in Section 3.3.4, Section 4.5.1 and Section 4.5.3(iii). 
 3.3.3 Second Restricted Stock Award. 
 (i) Subject to Board
approval (excluding the Executive), promptly following the Effective Date, the Company shall grant the Executive an additional award of restricted stock (the “Second Restricted Stock Award”) pursuant to the Plan for that
number of shares of Common Stock as is equal to approximately 1.333% (or 288,556 shares) of the Company’s Fully Diluted CSEs on the date of grant. 
 (ii) The Second Restricted Stock Award shall be granted subject to the terms and conditions of the Plan and a written award agreement to be entered into by the Company and the Executive (the
“Second Restricted Stock Award Agreement”). The Second Restricted Stock Award Agreement shall provide, among other things, that all shares of Common Stock underlying the Second Restricted Stock Award shall vest: (x) as
to 1/4th of the underlying shares, upon the first (1st) anniversary of the Vesting Commencement Date; and (y) as to the remaining underlying shares, in equal monthly installments over the following thirty-six (36) months such that all
shares shall be vested as of the fourth (4th) anniversary of the Vesting Commencement Date, subject to the Executive’s continued employment with the Company on each such vesting date; provided, however, that the Second
Restricted Stock Award shall be subject to accelerated vesting as provided in Section 3.3.4, Section 4.5.1 and Section 4.5.3(iii). 
 3.3.4 Acceleration of Equity Compensation. Immediately prior to the consummation of a Change in Control (as defined below), the vesting and exercisability of each of the Executive’s
outstanding stock awards (including any stock options, restricted stock, founder’s stock or other awards granted to the Executive by the Company) shall be automatically accelerated in full. 

3.4 Expense Reimbursements. The Company will reimburse the Executive for all reasonable business expenses the Executive incurs in
conducting his duties hereunder, pursuant to the Company’s usual expense reimbursement policies, provided that the Executive supplies the appropriate substantiation for such expenses. Any amounts payable under this Section 3.4 shall be
made in accordance with Treasury Regulation Section 1.409A-3(i)(1)(iv) and shall be paid on or before the last day of the Executive’s taxable year following the taxable year in which the Executive incurred the expenses. The amounts
provided under this Section 3.4 during any taxable year of the Executive’s will not affect such amounts provided in any other taxable year of the Executive’s, and the Executive’s right to reimbursement for such amounts shall not
be subject to liquidation or exchange for any other benefit. 
 3.5 Employment Taxes. All of the Executive’s
compensation shall be subject to all applicable federal, state and local taxes and withholdings, as well as any others that the Company determines it is legally required to withhold. 

3.6 Benefits; Vacation. The Executive shall, in accordance with Company policy and the terms of the applicable plan documents, be
eligible to participate in benefits under any benefit plan or arrangement that may be in effect from time to time and made available to the Company’s senior management employees, including with respect to additional coverage for spouses,
domestic partners and eligible dependents. In addition to the foregoing, the Executive shall be entitled to three (3) weeks’ paid vacation time per year, subject to a maximum accrual of three (3) weeks. 

  
 5 

 4. TERMINATION. 

4.1 Termination by the Company. The Executive’s employment with the Company is at will and may be terminated by the Company
at any time and for any reason, or for no reason, including, but not limited to, under the following conditions: 
 4.1.1
Termination by the Company for Cause. The Company may terminate the Executive’s employment under this Agreement for Cause (as defined below) by delivery of written notice to the Executive specifying the Cause or Causes relied upon for such
termination. Any notice of termination given pursuant to this Section 4.1.1 shall effect termination as of the date of the notice, or as of such other date as specified in the notice. 

4.1.2 Termination by the Company Without Cause. The Company may terminate the Executive’s employment under this Agreement
without Cause at any time and for any reason, or for no reason, by delivery of written notice to the Executive. Any notice of termination given pursuant to this Section 4.1.2 shall effect the termination of the Executive’s employment
hereunder as of the date of such notice, or as of such other date as is specified in such notice. 
 4.2 Termination by the
Executive. The Executive’s employment with the Company is at will and may be terminated by the Executive at any time and for any reason, or for no reason, including, but not limited to, under the following conditions: 

4.2.1 Termination by the Executive for Good Reason. The Executive may terminate his employment under this Agreement for Good
Reason (as defined below) in accordance with the procedures specified in Section 4.6.2 below. 
 4.2.2 Termination by
the Executive Without Good Reason. The Executive may terminate his employment under this Agreement for other than Good Reason at any time. 
 4.3 Termination for Death or Complete Disability. The Executive’s employment with the Company shall automatically terminate effective upon the date of the Executive’s death or Complete
Disability (as defined below). 
 4.4 Termination by Mutual Agreement of the Parties. The Executive’s employment
with the Company may be terminated at any time upon a written mutual agreement of the Parties. Any such termination of employment shall have the consequences specified in such agreement. 

  
 6 

 4.5 Compensation Upon Termination. 

4.5.1 Death or Complete Disability. If the Executive’s employment shall be terminated by death or Complete Disability as
provided in Section 4.3, the Company shall pay to the Executive, or to the Executive’s heirs, as applicable, the Base Salary and accrued and unused vacation benefits earned through the date of termination at the rate in effect at the time
of termination, plus all other amounts to which the Executive is entitled under any compensation plan or practice of the Company at the time of termination, less standard deductions and withholdings. In addition, the vesting and/or exercisability of
each of the Executive’s outstanding stock awards (including any stock options, restricted stock, founder’s stock or other awards granted to the Executive by the Company) shall be automatically accelerated on the date of termination as to
the number of stock awards that would have vested over the twelve (12) month period following the date of termination had the Executive remained continuously employed by the Company during such period. The Company shall thereafter have no
further obligations to the Executive and/or to the Executive’s heirs under this Agreement, except as otherwise provided by law. 
 4.5.2 With Cause or Without Good Reason. If the Executive’s employment is terminated by the Company for Cause, or if the Executive terminates his employment hereunder without Good Reason, the
Company shall pay to the Executive the Base Salary and accrued and unused vacation benefits earned through the date of termination at the rate in effect at the time of termination, plus all other amounts to which the Executive is entitled under any
compensation plan or practice of the Company at the time of termination, less standard deductions and withholdings. The Company shall thereafter have no further obligations to the Executive under this Agreement, except as otherwise provided by law.

 4.5.3 Without Cause or for Good Reason. If the Company terminates the Executive’s employment without Cause or
the Executive terminates his employment hereunder for Good Reason, the Company shall pay to the Executive the Base Salary and accrued and unused vacation benefits earned through the date of termination at the rate in effect at the time of
termination, plus all other amounts to which the Executive is entitled under any compensation plan or practice of the Company at the time of termination, less standard deductions and withholdings. In addition, subject to the Executive’s:
(i) furnishing to the Company an executed waiver and release of claims in substantially the form attached hereto as Exhibit B (which form may be amended to comply with legal requirements arising after the Effective Date) (the
“Release”) no later than forty-five (45) days following the Executive’s termination; and (ii) allowing the Release to become effective in accordance with its terms, the Executive shall be entitled to the
following: 
 (i) an amount equal to 100% of the Base Salary in effect at the time of termination (but determined prior
to any reduction in the Base Salary that would give rise to the Executive’s right to voluntarily resign for Good Reason pursuant to Section 4.6.2), less standard deductions and withholdings, paid in equal installments over a period of
twelve (12) months pursuant to the Company’s standard payroll practices (the “Cash Severance”); 
 (ii) should the Executive elect to continue Company-sponsored group health insurance benefits in accordance with the provisions of COBRA or State

  
 7 

 
Continuation, as applicable, following the date of termination, to the extent that doing so will not result in adverse tax consequences or violate applicable law, the Company shall pay the full
premium for such group health insurance continuation benefits for the Executive and any eligible dependents for a period of twelve (12) months after the effective date of the Release; provided, however, that any such payments will
cease if the Executive voluntarily enrolls in a health insurance plan offered by another employer or entity during the period in which the Company is paying such premiums. The Executive agrees to promptly notify the Company in writing of any such
enrollment. For purposes of this Section 4.5.3(ii), references to COBRA or State Continuation premiums shall not include any amounts payable by the Executive under an Internal Revenue Code Section 125 health care reimbursement plan; and

 (iii) the vesting and/or exercisability of each of the Executive’s outstanding stock awards (including any stock
options, restricted stock, founder’s stock or other awards granted to the Executive by the Company) shall be automatically accelerated on the date of termination as to the number of stock awards that would have vested over the twelve
(12) month period following the date of termination had the Executive remained continuously employed by the Company during such period. 

Notwithstanding the foregoing, in the event that the Company terminates the Executive’s employment without Cause but after providing the Executive
with: (i) written notice of the Board’s good-faith determination that the Executive’s participation in other activities pursuant to Section 2.1 is interfering with the Executive’s performance of his duties under this
Agreement; and (ii) a period of thirty (30) days to remedy such situation to the satisfaction of the Board in its reasonable discretion, the Executive shall be entitled, subject to the provisions of this Section 4.5.3 (including, for
the avoidance of doubt, the Executive’s (a) furnishing to the Company the Release no later than forty-five (45) days following the Executive’s termination and (b) allowing such Release to become effective in accordance with
its terms), to receive one-half of the benefits set forth in this Section 4.5.3. 
 4.6 Definitions. For purposes of
this Agreement, the following terms shall have the following meanings: 
 4.6.1 Complete Disability.
“Complete Disability” shall mean the inability of the Executive to perform the Executive’s duties under this Agreement, even with reasonable accommodation, because the Executive has become permanently disabled within the
meaning of any policy of long-term disability income insurance covering employees of the Company then in force. In the event the Company has no policy of disability income insurance covering employees of the Company in force when the Executive
becomes disabled, the term “Complete Disability” shall mean the inability of the Executive to perform the Executive’s duties under this Agreement, even with reasonable accommodation, by reason of any incapacity, physical or mental,
which the Board, based upon medical advice or an opinion provided by a licensed physician mutually acceptable to the Board and the Executive, determines to have incapacitated the Executive from satisfactorily performing all of the Executive’s
usual services for the Company, even with reasonable accommodation, for a period of at least one hundred twenty (120) days during any twelve (12) month period (whether or not consecutive). Based upon such medical advice or opinion, the
determination of the Board shall be final and binding and the date such determination is made shall be the date of such Complete Disability for purposes of this Agreement. 
 4.6.2 Good Reason. “Good Reason” for the Executive to terminate his employment hereunder shall mean the occurrence of any of the following events without the
Executive’s consent: 
 (i) a material diminution in the Executive’s authority, duties or responsibilities
relative to his authority, duties or responsibilities in effect immediately prior to such reduction; 

  
 8 

 (ii) a material change in the geographic location at which the Executive must
perform his duties to a point that is located more than fifty (50) miles from the Executive’s residence as set forth on the signature page hereto or, in the event that the Executive elects to perform the services required by this Agreement
at any other business office established by the Company, a material change in the geographic location at which the Executive must perform his duties to a point that is located more than fifty (50) miles from such business office; 

(iii) a material diminution by the Company of the Executive’s base compensation as initially set forth herein or as the same
may be increased from time to time; or 
 (iv) any other action or inaction that constitutes a material breach by the
Company or any successor or Affiliate of its obligations to the Executive under this Agreement; provided, however, that such termination by the Executive shall only be deemed for Good Reason pursuant to the foregoing definition if:
(x) the Executive gives the Company written notice of the intent to terminate for Good Reason within thirty (30) days following the first occurrence of the condition(s) that the Executive believes constitutes Good Reason, which notice
shall describe such condition(s); (y) the Company fails to remedy such condition(s) within thirty (30) days following receipt of the written notice (the “Cure Period”); and (z) the Executive terminates his
employment within thirty (30) days following the end of the Cure Period. 
 4.6.3 Cause.
“Cause” for the Company to terminate the Executive’s employment hereunder shall mean the occurrence of any of the following events, as determined by the Board or a committee designated by the Board, in its sole
discretion: 
 (i) the Executive’s conviction of any felony or any crime involving moral turpitude or dishonesty;

 (ii) the Executive’s participation in a fraud involving or against the Company; 

(iii) the Executive’s willful and material breach of the Executive’s duties hereunder that is not cured within thirty
(30) days after the Executive’s receipt of written notice from the Board of such breach; 
 (iv) the
Executive’s intentional and material damage to the Company’s property; or 
 (v) the Executive’s material
breach of the Non-Disclosure and Assignment Agreement (as defined below); 

  
 9 

 provided, however, that prior to the determination that Cause under this Section 4.6.3
has occurred, the Company shall: (w) provide to the Executive in writing, in reasonable detail, the reasons for the determination that such Cause exists; (x) other than with respect to clause (iii) above which specifies the applicable
period of time for the Executive to remedy his breach, afford the Executive a reasonable opportunity to remedy any such breach; (y) provide the Executive an opportunity to be heard prior to the final decision to terminate the Executive’s
employment hereunder for such Cause; and (z) make any decision that such Cause exists in good faith. 
 4.6.4 Change in
Control. “Change in Control” shall mean the occurrence, in a single transaction or in a series of related transactions, of any one or more of the following events: (i) there is consummated a merger, consolidation or
similar transaction involving (directly or indirectly) the Company if, immediately after the consummation of such merger, consolidation or similar transaction, the stockholders of the Company immediately prior thereto do not own, directly or
indirectly, either (a) outstanding voting securities representing more than fifty percent (50%) of the combined outstanding voting power of the surviving entity in such merger, consolidation or similar transaction or (b) more than
fifty percent (50%) of the combined outstanding voting power of the parent of the surviving entity in such merger, consolidation or similar transaction; (ii) the stockholders of the Company approve or the Board approves a plan of complete
dissolution or liquidation of the Company, or a complete dissolution or liquidation of the Company shall otherwise occur; or (iii) there is consummated a sale of all or substantially all of the consolidated assets of the Company and its
subsidiaries, other than a sale of all or substantially all of the consolidated assets of the Company and its subsidiaries to an entity more than fifty percent (50%) of the combined voting power of the voting securities of which entity is owned
by stockholders of the Company in substantially the same proportion as their ownership of the Company immediately prior to such sale; provided, however, that the term “Change in Control” shall not include a sale of assets,
merger or other transaction effected exclusively for the purpose of changing the domicile of the Company. 
 4.7 Survival of
Certain Sections. Sections 2.2, 2.3, 3.3.4, 4, 5, 6, 7, 8, 9, 12, 13, 16 and 18 of this Agreement will survive the termination of this Agreement. 
 4.8 Parachute Payment. If any payment or benefit the Executive would receive pursuant to this Agreement (each, a “Payment”) would: (i) constitute a
“Parachute Payment” within the meaning of Section 280G of the Internal Revenue Code of 1986, as amended (the “Code”); and (ii) but for this sentence, be subject to the excise tax imposed by
Section 4999 of the Code (the “Excise Tax”), then such Payment shall be reduced to the Reduced Amount. The “Reduced Amount” shall be equal to the largest portion of the Payment (including all of
it) which, after taking into account all applicable federal, state and local income and employment taxes (all computed at the highest applicable marginal rate), and the Excise Tax, if applicable, results in the Executive’s receipt, on an
after-tax basis, of the greatest amount of the Payment, whether or not all or some portion of the Payment is subject to the Excise Tax. If a reduction in payments or benefits constituting Parachute Payments is necessary so that the Payment equals
the Reduced Amount, reduction shall occur in the following order unless the 

  
 10 

 
Executive elects in writing a different order (provided, however, that such election shall be subject to Company approval if made on or after the effective date of the event that
triggers the Payment): reduction of cash payments; cancellation of accelerated vesting of stock awards; reduction of employee benefits. In the event that acceleration of vesting of stock award compensation is to be reduced, such acceleration of
vesting shall be cancelled in the reverse order of the date of grant of the Executive’s stock awards unless the Executive elects in writing a different order for cancellation. Notwithstanding anything to the contrary set forth herein, the
Executive may not elect the order in which the reduction in the Executive’s payments or benefits will occur if such election would cause any such amounts to constitute “nonqualified deferred compensation” within the meaning of
Section 409A of the Code such that the Executive would incur the additional twenty percent (20%) tax under Section 409A of the Code (the “409A Tax”). In addition, if a different order of reduction is required
to avoid the 409A Tax, that order shall apply. 
 The accounting firm then engaged by the Company for general audit purposes
shall perform the foregoing calculations. The Company shall bear all expenses with respect to the determinations by such accounting firm required to be made hereunder. 
 The accounting firm engaged to make the determinations hereunder shall provide its calculations, together with detailed supporting documentation, to the Executive and the Company within fifteen
(15) calendar days after the date on which the Executive’s right to a Payment is triggered (if requested at that time by the Executive or the Company) or such other time as requested by the Executive or the Company. If the accounting firm
determines that no Excise Tax is payable with respect to a Payment, either before or after the application of the Reduced Amount, it shall furnish the Executive and the Company with an opinion reasonably acceptable to the Executive that no Excise
Tax will be imposed with respect to such Payment. Any good faith determinations of the accounting firm made hereunder shall be final, binding and conclusive upon the Executive and the Company. 

4.9 Application of Internal Revenue Code Section 409A. Notwithstanding anything to the contrary set forth herein, any Cash
Severance amounts that constitute “nonqualified deferred compensation” within the meaning of Section 409A of the Code shall not commence in connection with the Executive’s termination of employment unless and until the Executive
has also incurred a “separation from service” within the meaning of Section 409A of the Code, unless the Company reasonably determines that such amounts may be provided to the Executive without causing the Executive to incur the 409A
Tax. To the extent any Cash Severance amounts: (i) are paid following the date of termination of the Executive’s employment through March 15 of the calendar year following such termination, such severance benefits are intended to
constitute separate payments for purposes of Section 1.409A-2(b)(2) of the Treasury Regulations and thus payable pursuant to the “short-term deferral” rule set forth in Section 1.409A-1(b)(4) of the Treasury Regulations;
(ii) are paid following said March 15, such Cash Severance benefits are intended to constitute separate payments for purposes of Section 1.409A-2(b)(2) of the Treasury Regulations made upon an involuntary separation from service and
payable pursuant to Section 1.409A-1(b)(9)(iii) of the Treasury Regulations, to the maximum extent permitted by said provision; and (iii) are in excess of the amounts specified in clauses (i) and (ii) of this paragraph, shall
(unless otherwise exempt under Treasury Regulations) be considered separate payments subject to the distribution requirements of 

  
 11 

 
Section 409A(a)(2)(A) of the Code, including, without limitation, the requirement of Section 409A(a)(2)(B)(i) of the Code that payments or benefits be delayed until six (6) months
and one (1) day after the Executive’s separation from service if the Executive is a “specified employee” within the meaning of the aforesaid section of the Code at the time of such separation from service. In the event that a six
(6) month and one (1) day delay of any such separation payments or benefits is required, on the first regularly scheduled pay date following the conclusion of the delay period the Executive shall receive a lump sum payment or benefit in an
amount equal to the separation payments and benefits that were so delayed, and any remaining separation payments or benefits shall be paid on the same basis and at the same time as otherwise specified pursuant to this Agreement (subject to
applicable tax withholdings and deductions). 
 5. CONFIDENTIAL AND PROPRIETARY
INFORMATION. As a condition of employment, the Executive agrees to execute and abide by the Company’s standard form of Non-Disclosure and Proprietary Rights Assignment Agreement (the “Non-Disclosure and Assignment
Agreement”). 
 6. ASSIGNMENT AND BINDING
EFFECT. This Agreement shall be binding upon and inure to the benefit of the Executive and the Executive’s heirs, executors, personal representatives, assigns, administrators and legal representatives. Because of the unique
and personal nature of the Executive’s duties under this Agreement, neither this Agreement nor any rights or obligations under this Agreement shall be assignable by the Executive. This Agreement shall be binding upon and inure to the benefit of
the Company and its successors, assigns and legal representatives. Any such successor of the Company will be deemed substituted for the Company under the terms of this Agreement for all purposes and the Company will require any successor to all or
substantially all of the business or assets of the Company expressly to assume and to agree to perform this Agreement in the same manner and to the same extent that the Company would be required to perform it if no such succession had taken place.
For this purpose, “successor” means any person, firm, corporation or other business entity which at any time, whether by purchase, merger or otherwise, directly or indirectly acquires all or substantially all of the assets or business of
the Company. 
 7. NOTICES. All notices or demands of any kind required or permitted to be given by the
Company or the Executive under this Agreement shall be given in writing and shall be personally delivered (and receipted for) or faxed during normal business hours or mailed by certified mail, return receipt requested, postage prepaid, addressed as
follows: 
 If to the Company: 
 Aratana Therapeutics, Inc. 
 1901 Olathe Boulevard 

Kansas City, KS 66103 
 Attention: Chairman of the Board 
 If to the Executive, to the address set forth
on the signature page hereto. 
 Any such written notice shall be deemed given on the earlier of the date on which such notice is personally
delivered or three (3) days after its deposit in the United States mail as specified above. Either Party may change its address for notices by giving notice to the other Party in the manner specified in this section. 

  
 12 

 8. CHOICE OF LAW. This Agreement shall
be construed and interpreted in accordance with the internal laws of the State of Delaware. The Executive and the Company consent to non-exclusive personal jurisdiction in any state and, if otherwise permitted by law, federal court situated in the
State of Delaware for the resolution of all claims arising under this Agreement that are subject to resolution in court rather than through arbitration. 
 9. INTEGRATION. This Agreement, including the exhibits hereto, together with the Non-Disclosure and Assignment Agreement, contains the complete, final and exclusive agreement of the
Parties relating to the terms and conditions of the Executive’s employment and the termination of the Executive’s employment, and supersedes all prior oral and written employment agreements or arrangements between the Parties. 

10. AMENDMENT. This Agreement cannot be amended or modified except by a written agreement signed by the Executive
and the Company. 
 11. WAIVER. No term, covenant or condition of this Agreement or any breach thereof
shall be deemed waived, except with the written consent of the Party against whom the wavier is claimed, and any waiver or any such term, covenant, condition or breach shall not be deemed to be a waiver of any preceding or succeeding breach of the
same or any other term, covenant, condition or breach. 
 12. SEVERABILITY. The finding by a court of
competent jurisdiction of the unenforceability, invalidity or illegality of any provision of this Agreement shall not render any other provision of this Agreement unenforceable, invalid or illegal. Such court shall have the authority to modify or
replace the invalid or unenforceable term or provision with a valid and enforceable term or provision, which most accurately represents the Parties’ intention with respect to the invalid or unenforceable term, or provision. 

13. INTERPRETATION; CONSTRUCTION. The headings set forth in this Agreement are for convenience of
reference only and shall not be used in interpreting this Agreement. This Agreement has been drafted by legal counsel representing the Company, but the Executive has been encouraged to consult with, and has consulted with, the Executive’s own
independent counsel and tax advisors with respect to the terms of this Agreement. The Parties acknowledge that each Party and its counsel has reviewed and revised, or had an opportunity to review and revise, this Agreement, and any rule of
construction to the effect that any ambiguities are to be resolved against the drafting party shall not be employed in the interpretation of this Agreement. 
 14. REPRESENTATIONS AND WARRANTIES. The Executive represents and warrants that the Executive is not restricted or prohibited, contractually or
otherwise, from entering into and performing each of the terms and covenants contained in this Agreement, and that the Executive’s execution and performance of this Agreement will not violate or breach any other agreements between the Executive
and any other person or entity. 

  
 13 

 15. COUNTERPARTS. This Agreement may be executed in two
(2) counterparts, each of which shall be deemed an original, all of which together shall constitute one and the same instrument. 
 16. ARBITRATION. To ensure the rapid and economical resolution of disputes that may arise in connection with the Executive’s employment with the Company, the Executive and the
Company agree that any and all disputes, claims, or causes of action, in law or equity, arising from or relating to the Executive’s employment, or the termination of that employment, will be resolved, to the fullest extent permitted by law, by
final, binding and confidential arbitration pursuant to the Federal Arbitration Act in Kansas City, Kansas conducted by the Judicial Arbitration and Mediation Services/Endispute, Inc. (“JAMS”), or its successors, under the
then current rules of JAMS for employment disputes; provided that the arbitrator shall: (a) have the authority to compel adequate discovery for the resolution of the dispute and to award such relief as would otherwise be permitted by
law; and (b) issue a written arbitration decision including the arbitrator’s essential findings and conclusions and a statement of the award. ACCORDINGLY, THE EXECUTIVE AND THE COMPANY HEREBY IRREVOCABLY WAIVE ANY RIGHT TO A JURY TRIAL IN
ANY LEGAL PROCEEDING ARISING OUT OF OR RELATING TO THIS AGREEMENT. Both the Executive and the Company shall be entitled to all rights and remedies that either the Executive or the Company would be entitled to pursue in a court of law. The Company
shall pay any JAMS filing fee and shall pay the arbitrator’s fee. The arbitrator shall have the discretion to award attorneys’ fees to the party the arbitrator determines is the prevailing party in the arbitration; provided,
however, that the prevailing party shall be reimbursed for such fees, costs and expenses within sixty (60) days following any such award, but, to the extent the Executive is the prevailing party, in no event later than the last day of
the Executive’s taxable year following the taxable year in which the fees, costs and expenses were incurred; provided, further, that the Parties’ obligations pursuant to the provisos set forth above shall terminate on the
tenth (10th) anniversary of the date of the Executive’s termination of employment. Nothing in this Agreement is intended to prevent either the Executive or the Company from obtaining equitable relief in court to prevent irreparable harm
pending the conclusion of any such arbitration. Notwithstanding the foregoing, the Executive and the Company each have the right to resolve any issue or dispute involving a claim of misappropriation or infringement of confidential, proprietary or
trade secret information, or intellectual property rights, in any court of competent jurisdiction instead of via arbitration. 

17. TRADE SECRETS OF OTHERS. It is the understanding and intention of
both the Company and the Executive that the Executive shall not divulge to the Company and/or its subsidiaries any confidential information or trade secrets belonging to others, including the Executive’s former employers, nor shall the Company
and/or its Affiliates seek to elicit from the Executive any such information. The Executive shall not provide to the Company and/or its Affiliates or use on their behalf any such information or any documents or copies of documents containing such
information. 
 18. ADVERTISING WAIVER. The Executive agrees to permit, during and
following the term of this Agreement, and without receiving additional compensation, the Company, and persons or other organizations authorized by the Company, to use, publish and distribute advertising or sales promotional literature concerning the
products and/or services of the Company, or the machinery and equipment used in the provision thereof, in which the 

  
 14 

 
Executive’s name and/or pictures of the Executive taken in the course of the Executive’s provision of services to the Company appear. The Executive hereby waives and releases any claim
or right the Executive may otherwise have arising out of such use, publication or distribution. 
 [REMAINDER OF PAGE
INTENTIONALLY LEFT BLANK] 

  
 15 

 IN WITNESS WHEREOF, the
Parties have executed this Agreement as of the date first written above. 
  

			
	ARATANA THERAPEUTICS, INC.
	
	 /s/ Jay B. Lichtar

	By:	 	Jay B Lichtar
	Its:	 	Chairman
	
	Dated: September 25, 2012

			
	
	EXECUTIVE:
	
	 /s/ Steven St. Peter

	STEVEN ST. PETER
	
	Dated: September 25, 2012
		
	Address:	 	 43 Union Park #2

		 	 Boston, MA 02118

 [SIGNATURE PAGE TO EMPLOYMENT AGREEMENT] 

 EXHIBIT A 
 PERMITTED ACTIVITIES 
  

	1)	PharmAthene, Inc. (Amex: PIP) 

  

	 	•	 	 Member of Board of Directors 

  

	 	•	 	 Member of Governance & Nominating Committee 

  

	2)	EKR Therapeutics, Inc. 

  

	 	•	 	 Member of Shareholder Representative Committee 

  

	3)	Vie Ventures 

  

	 	•	 	 Managing Director 

  

	4)	Rental Real Estate Activities 

  

	 	•	 	 Ownership of three rental real estate properties 

 EXHIBIT B 
 RELEASE AND WAIVER OF CLAIMS 
 TO BE SIGNED FOLLOWING TERMINATION WITHOUT
CAUSE 
 OR RESIGNATION FOR GOOD REASON 
 In consideration of the payments and other benefits set forth in the Employment Agreement dated September 6, 2012 (the “Employment Agreement”), to which this form is attached,
I, Steven St. Peter, hereby furnish ARATANA THERAPEUTICS, INC. (the “Company”), with the following release and waiver (“Release and Waiver”).

 In exchange for the consideration provided to me by Section 4 of the Employment Agreement that I am not otherwise
entitled to receive, I hereby generally and completely release the Company and its directors, officers, employees, shareholders, partners, agents, attorneys, predecessors, successors, parent and subsidiary entities, insurers, Affiliates, and assigns
from any and all claims, liabilities and obligations, both known and unknown, that arise out of or are in any way related to events, acts, conduct, or omissions occurring prior to my signing this Release and Waiver, except claims that the law does
not permit me to waive by signing this Release and Waiver. This general release includes, but is not limited to: (1) all claims arising out of or in any way related to my employment with the Company or the termination of that employment;
(2) all claims related to my compensation or benefits from the Company, including salary, bonuses, commissions, vacation pay, expense reimbursements, severance pay, fringe benefits, stock, stock options, or any other ownership interests in the
Company; (3) all claims for breach of contract, wrongful termination, and breach of the implied covenant of good faith and fair dealing; (4) all tort claims, including claims for fraud, defamation, emotional distress, and discharge in
violation of public policy; and (5) all federal, state, and local statutory claims, including claims for discrimination, harassment, retaliation, attorneys’ fees, or other claims arising under the federal Civil Rights Act of 1964 (as
amended), the federal Americans with Disabilities Act of 1990, the federal Age Discrimination in Employment Act of 1967 (as amended) (“ADEA”), the Kansas Anti-discrimination Act and the Kansas Age Discrimination in Employment
Act. 
 Notwithstanding the foregoing, nothing in this Release and Waiver shall constitute a release by me of any claims or
damages based on any right I may have to enforce the Company’s executory obligations under the Employment Agreement, or my eligibility for indemnification under applicable law, Company governance documents, my indemnification agreement with the
Company or under any applicable insurance policy with respect to my liability as an employee or officer of the Company, or my rights pursuant to my stock awards (including any stock options, restricted stock, founder’s stock or other awards
granted to me by the Company) pursuant to their terms. 
 I acknowledge that, among other rights, I am waiving and releasing any
rights I may have under ADEA, that this Release and Waiver is knowing and voluntary, and that the consideration given for this Release and Waiver is in addition to anything of value to which I was already entitled as an executive of the Company. If
I am 40 years of age or older upon execution of this Release and Waiver, I further acknowledge that I have been advised, as required by the Older 

 
Workers Benefit Protection Act, that: (a) the release and waiver granted herein does not relate to claims under the ADEA which may arise after this Release and Waiver is executed; (b) I
should consult with an attorney prior to executing this Release and Waiver; (c) I have twenty-one (21) days from the date of termination of my employment with the Company in which to consider this Release and Waiver (although I may choose
voluntarily to execute this Release and Waiver earlier); (d) I have seven (7) days following the execution of this Release and Waiver to revoke my consent to this Release and Waiver; and (e) this Release and Waiver shall not be
effective until the seven (7) day revocation period has expired. 
 I acknowledge my continuing obligations under my
Non-Disclosure and Assignment Agreement. Pursuant to the Non-Disclosure and Assignment Agreement I understand that among other things, I must not use or disclose any confidential or proprietary information of the Company and I must promptly return
all Company property and documents (including all embodiments of proprietary information) and all copies thereof in my possession or control. I understand and agree that my right to the severance pay I am receiving in exchange for my agreement to
the terms of this Release and Waiver is contingent upon my continued compliance with my Non-Disclosure and Assignment Agreement. 
 This Release and Waiver constitutes the complete, final and exclusive embodiment of the entire agreement between the Company and me with regard to the subject matter hereof. I am not relying on any
promise or representation by the Company that is not expressly stated herein. This Release and Waiver may only be modified by a writing signed by both me and a duly authorized officer of the Company. 

 

									
	Date:	 	  
	 		 	By:	 	  

					
		 		 		 	Name:	 	  

 ARATANA THERAPEUTICS, INC. 

AMENDMENT NO. 1 TO 
 EMPLOYMENT AGREEMENT 
 THIS AMENDMENT
NO. 1 TO EMPLOYMENT AGREEMENT (this “Amendment”) is made and entered into as of April 26, 2013, by and
between ARATANA THERAPEUTICS, INC., a Delaware corporation (the “Company”), and Steven St. Peter (the
“Executive”). Capitalized terms used and not otherwise defined herein shall have the meanings given to them in the Original Agreement (as defined below). 

RECITALS 

WHEREAS, the Company and the Executive are parties to that certain Employment Agreement, dated as of
September 6, 2012 (the “Original Agreement”); and 
 WHEREAS, in accordance
with Section 10 of the Original Agreement, the Company and the Executive desire to amend the Original Agreement as set forth in this Amendment. 
 NOW, THEREFORE, in consideration of the mutual covenants contained herein, and for other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, the parties agree as follows: 
 AMENDMENT 

1. AMENDMENTS TO ORIGINAL AGREEMENT. 

1.1 Amendment to Section 2.2. The fourth sentence of Section 2.2 of the Original Agreement is hereby amended and
restated in its entirety to read as follows: 
 “Accordingly, the Executive agrees that during the Term and
for (i) eighteen (18) months following the termination of his employment by the Company without Cause (as defined below) or by the Executive for Good Reason (as defined below) during the Double-Trigger Period (as defined below), or
(ii) twelve (12) months following the termination of his employment for any other reason, the Executive shall not engage in competition with the Company and/or any of its Affiliates (as defined below), either directly or indirectly, in any
manner or capacity, as adviser, principal, agent, Affiliate, promoter, partner, officer, director, employee, stockholder, owner, co-owner, consultant or member of any association or otherwise, in any phase of the business of developing, licensing,
manufacturing, distributing or marketing of products or services that are in the same Field of Use (as defined below) or which are otherwise in competition with the actual or reasonably anticipated products or services of the Company at the time of
his separation from the Company, except with the prior written consent of the Board.” 

 1.2 Amendment to Section 3.2. Section 3.2 of the Original Agreement is
hereby amended and restated in its entirety to read as follows: 
 “3.2 Annual Bonus. The Executive
will be eligible to receive an annual cash bonus (the “Bonus”) of up to fifty percent (50%) of the Base Salary with respect to each calendar year, subject to the Executive’s continued employment with the Company as
of the end of such calendar year and contingent upon successful achievement of corporate objectives established from year to year by the Board (excluding the Executive). Any Bonus pursuant to this Section 3.2 shall be paid as promptly as
practicable following the end of the applicable calendar year, but not later than March 15th of the following calendar year.” 
 1.3 Amendment to Section 3.3.1. Section 3.3.1 of the Original Agreement is hereby retitled “Stock Options” and is hereby amended by adding the following subparagraphs
(iii) and (iv) following existing subparagraph (ii): 
 “(iii) On the date the Company’s
registration statement relating to its initial public offering becomes effective (the “IPO Effective Date”), the Company shall grant the Executive a stock option (the “IPO Stock Option”) pursuant to
the Company’s 2013 Incentive Award Plan or such other equity incentive plan or similar plan in effect on the IPO Effective Date (the “New Plan”) to purchase 250,000 shares of Common Stock (adjusted for any stock splits,
reverse stock splits or other changes affecting the shares of Common Stock that may occur prior to the date of grant), at a per share exercise price equal to the fair market value of a share of Common Stock on the date of grant. 

(iv) The IPO Stock Option shall be granted subject to the terms and conditions of the New Plan and a written option
agreement to be entered into by the Company and the Executive (the “IPO Option Agreement”). The IPO Option Agreement shall provide, among other things, that the shares of Common Stock underlying the IPO Stock Option (the
“IPO Option Shares”) shall vest: (x) as to 1/4th of the IPO Option Shares, upon the first (1st) anniversary of the date of grant of the IPO Stock Option; and (y) as to the remaining IPO Option Shares, in equal
monthly installments over the next thirty-six (36) months such that all shares shall be vested as of the fourth (4th) anniversary of the date of grant of the IPO Stock Option, subject to the Executive’s continued employment with the
Company on each such vesting date; provided, however, that: (a) the IPO Stock Option shall be subject to accelerated vesting as provided in Section 4.5.1 and Section 4.5.3(iii); and (b) “early exercise” of
the IPO Stock Option shall be permitted pursuant to the terms of the New Plan and the IPO Option Agreement.” 

  
 2 

 1.4 Amendment to Section 3.3.4. Section 3.3.4 of the Original Agreement is
hereby amended and restated in its entirety to read as follows: 
 3.3.4 Acceleration of Equity
Compensation. Immediately prior to the consummation of a Change in Control (as defined below), the vesting and exercisability of each of the Executive’s outstanding Existing Awards (as defined below) shall be automatically accelerated in
full.” 
 1.5 Amendment to Section 4.5.3. Section 4.5.3 of the Original Agreement is hereby amended and
restated in its entirety to read as follows: 
 “4.5.3 Without Cause or for Good Reason. If the
Company terminates the Executive’s employment without Cause or the Executive terminates his employment hereunder for Good Reason, the Company shall pay to the Executive the Base Salary and accrued and unused vacation benefits earned through the
date of termination at the rate in effect at the time of termination, plus all other amounts to which the Executive is entitled under any compensation plan or practice of the Company at the time of termination, less standard deductions and
withholdings. In addition, subject to the Executive’s: (i) furnishing to the Company an executed waiver and release of claims in substantially the form attached hereto as Exhibit B (which form may be amended to comply with legal
requirements arising after the Effective Date) (the “Release”) no later than forty-five (45) days following the Executive’s termination; and (ii) allowing the Release to become effective in accordance with its
terms, the Executive shall be entitled to the following: 
 (i) payment in an amount equal to 100% of the
Executive’s annual Base Salary in effect at the time of termination (or, in the event the termination occurs on account of or within twelve (12) months following the date of the consummation of a Change in Control (as defined below) (such
period, the “Double-Trigger Period”), an amount equal to 150% of the sum of (A) the Base Salary in effect at the time of termination, plus (B) the target cash bonus in effect for the year of termination) (with the
amount of the Base Salary determined prior to any reduction in the Base Salary that would give rise to the Executive’s right to voluntarily resign for Good Reason pursuant to Section 4.6.2), less standard deductions and withholdings, paid
in equal installments over a period of twelve (12) months (or eighteen (18) months, in the event the termination occurs during the Double-Trigger Period) pursuant to the Company’s standard payroll practices (the “Cash
Severance”); 
 (ii) should the Executive elect to continue Company-sponsored group health insurance
benefits in accordance with the provisions of COBRA or State Continuation, as applicable, following the date of termination, to the extent that doing so will not result in adverse tax consequences or violate applicable law, the Company shall pay the
full premium for such group health insurance continuation benefits for the Executive and any eligible dependents for a period of twelve (12) months (or eighteen (18) months, in the event the termination occurs during the

  
 3 

 
Double-Trigger Period) after the effective date of the Release; provided, however, that any such payments will cease if the Executive voluntarily enrolls in a health insurance plan
offered by another employer or entity during the period in which the Company is paying such premiums. The Executive agrees to promptly notify the Company in writing of any such enrollment. For purposes of this Section 4.5.3(ii), references to
COBRA or State Continuation premiums shall not include any amounts payable by the Executive under an Internal Revenue Code Section 125 health care reimbursement plan; and 

(iii) the vesting and/or exercisability of each of the Executive’s outstanding stock awards (including any stock
options, restricted stock, founder’s stock or other awards granted to the Executive by the Company) shall be automatically accelerated on the effective date of the Release as to the number of stock awards that would have vested over the twelve
(12) month period following the date of termination had the Executive remained continuously employed by the Company during such period; provided, however, that in the event that the termination occurs during the Double-Trigger
Period, the vesting and exercisability of each of the Executive’s outstanding New Awards (as defined below) shall be automatically accelerated in full, which shall mean at target for any portion of the New Awards that vests based on the
achievement of performance goals. 
 Notwithstanding the foregoing, in the event that the Company terminates the
Executive’s employment without Cause but after providing the Executive with: (i) written notice of the Board’s good-faith determination that the Executive’s participation in other activities pursuant to Section 2.1 is
interfering with the Executive’s performance of his duties under this Agreement; and (ii) a period of thirty (30) days to remedy such situation to the satisfaction of the Board in its reasonable discretion, the Executive shall be
entitled, subject to the provisions of this Section 4.5.3 (including, for the avoidance of doubt, the Executive’s (a) furnishing to the Company the Release no later than forty-five (45) days following the Executive’s
termination and (b) allowing such Release to become effective in accordance with its terms), to receive one-half of the benefits set forth in this Section 4.5.3.” 

1.6 Amendment to Section 4.6. Section 4.6 of the Original Agreement is hereby amended by adding the following
definitions: 
 “4.6.5 Existing Awards. “Existing Awards” shall mean the
Consulting Option, the Stock Option, the First Restricted Stock Award and the Second Restricted Stock Award. 

4.6.6 New Awards. “New Awards” shall mean the IPO Stock Option and any other stock options,
restricted stock or other equity awards granted to the Executive by the Company, with the exception of the Existing Awards. 

  
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 2. MISCELLANEOUS 

2.1 Effective Date. This Amendment shall become effective on the IPO Effective Date, if and only if the following conditions (the
“Conditions”) are satisfied: (i) the Executive is still employed by the Company on the IPO Effective Date, and (ii) the IPO Effective Date is no later than September 30, 2013. For the avoidance of doubt, if
either of the Conditions is not satisfied, this Amendment shall be of no force or effect and shall not become effective. 

2.2 No Other Amendment. Except as specifically amended by this Amendment, the terms and conditions of the Original Agreement shall
remain unchanged and in full force and effect. 
 2.3 Counterparts; Execution by Facsimile. This Amendment may be
executed in any number of counterparts, each of which shall be deemed an original and all of which together shall constitute one and the same instrument. The exchange of copies of this Amendment and of signature pages thereto by facsimile
transmission or by e-mail transmission in portable digital format, or similar format, shall constitute effective execution and delivery of such instrument(s) by the parties and may be used in lieu of the original Amendment for all purposes.

 [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK] 

  
 5 

 IN WITNESS WHEREOF, the
parties have duly executed and delivered this AMENDMENT NO. 1 TO EMPLOYMENT AGREEMENT as of the date first written above. 

 

			
	COMPANY:
	
	ARATANA THERAPEUTICS, INC.
		
	By:	 	/s/ Jay Lichter
	Name:	 	Jay Lichter
	Its:	 	Chairman
		
	Dated:	 	4/26/2013

  

			
	EXECUTIVE:
	
	/s/ Steven St. Peter
	STEVEN ST. PETER
		
	Dated:	 	4/26/2013

 [SIGNATURE PAGE TO AMENDMENT NO. 1 TO EMPLOYMENT AGREEMENT]

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