Document:

EX-4.1

 Exhibit 4.1 

 
 

 
 INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE This
Certifies that is the record holder of COUNTERSIGNED AND REGISTERED: AMERICAN STOCK TRANSFER & TRUST COMPANY, LLC (Brooklyn, NY) TRANSFER AGENT AND REGISTRAR BY AUTHORIZED SIGNATURE CUSIP 03874P 10 1 SEE REVERSE FOR CERTAIN DEFINITIONS
transferable on the books of the Corporation by the holder hereof in person or by duly authorized attorney upon surrender of this certificate properly endorsed. This certificate is not valid until countersigned by the Transfer Agent and registered
by the Registrar. WITNESS the facsimile signatures of the Corporation’s duly authorized officers. Dated: ATI FULLY PAID AND NONASSESSABLE SHARES OF COMMON STOCK, $0.001 PAR VALUE, OF Aratana Therapeutics, Inc. President and Chief Executive
Officer Chief Financial Officer Aratana Therapeutics, Inc. ARATANA T H E R A P E U T I C S SPECIMEN 

 

 
 FOR VALUE RECEIVED, hereby sell, assign and transfer unto The following abbreviations,
when used in the inscription on the face of this certificate, shall be construed as though they were written out in full according to applicable laws or regulations: TEN COM TEN ENT JT TEN – as tenants in common – as tenants by the
entireties – as joint tenants with right of survivorship and not as tenants in common (PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING POSTAL ZIP CODE, OF ASSIGNEE) Shares Attorney of the common stock represented by the within
Certificate, and do hereby irrevocably constitute and appoint PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE to transfer the said stock on the books of the within named Corporation with full power of substitution in the
premises. Dated Signature(s) Guaranteed THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION
PROGRAM), PURSUANT TO S.E.C. RULE 17Ad-15. Additional abbreviations may also be used though not in the above list. NOTICE: X X UNIF GIFT MIN ACT – Custodian (Cust) (Minor) under Uniform Gifts to Minors Act (State) THE SIGNATURE(S) TO THIS
ASSIGNMENT MUST CORRESPOND WITH THE NAME(S) AS WRITTEN UPON THE FACE OF THE CERTIFICATE, IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATEVER.EX-10.1

 Exhibit 10.1 
 SECOND AMENDED AND RESTATED 
 INVESTORS’ RIGHTS AGREEMENT

 THIS SECOND AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT (this “Agreement”) is
made and entered into as of December 28, 2012, by and among ARATANA THERAPEUTICS, INC., a Delaware corporation (the “Company”), and the investors set forth on the Schedule of Investors attached hereto as
Exhibit A (each, an “Investor” and collectively, the “Investors”). 

RECITALS 

WHEREAS, the Company and certain of the Investors (the “Existing Investors”) are parties to that certain
Series A Preferred Stock Purchase Agreement (the “Series A Purchase Agreement”) or that certain Series A-1 Preferred Stock Purchase Agreement (the “Series A-1 Purchase Agreement”
and, together with the Series A Purchase Agreement, the “Prior Purchase Agreements”), each dated as of December 27, 2010; and 
 WHEREAS, as a condition of entering into the Prior Purchase Agreements, the Existing Investors and the Company executed that certain Investors’ Rights Agreement dated as of December 27,
2010 among the Company and such Investors (the “Prior Agreement”); and 
 WHEREAS, the Company
and certain of the Investors (the “Series B Investors”) are parties to that certain Series B Preferred Stock Purchase Agreement dated as of November 1, 2011, among the Company and the Series B Investors
(the “Series B Purchase Agreement”); and 
 WHEREAS, as a condition of entering into the
Series B Purchase Agreement, the Series B Investors, the Existing Investors and the Company executed that certain First Amended and Restated Investors’ Rights Agreement dated as of November 1, 2011 (the “Restated Prior
Agreement”). 
 WHEREAS, certain of the Investors (the “Series C Investors”)
are parties to that certain Series C Preferred Stock Purchase Agreement of even date herewith among the Company and the Series C Investors (the “Series C Purchase Agreement”); and 

WHEREAS, as a condition of entering into the Series C Purchase Agreement, the Series C Investors have requested that the
Company and Existing Investors and Series B Investors representing at least the Majority Investors amend and restate the Restated Prior Agreement as set forth below. 
 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 Existing Investors and the Series B Investors hereby agree that the Restated Prior Agreement shall be amended and restated, and the parties to this Agreement further agree as
follows: 

 AGREEMENT 

 

	1.	REGISTRATION RIGHTS. 

1.1 Definitions. For purposes of this Agreement: 
 (a) The term “Board of Directors” means the Board of Directors of the Company. 
 (b) The term “Certificate of Incorporation” means the Third Amended and Restated Certificate of Incorporation of the Company of even date herewith. 

(c) The term “Common Stock” means the Common Stock, $0.001 par value per share, of the Company.

 (d) The term “Exchange Act” means the Securities Exchange Act of 1934, as amended. 

(e) The term “Form S-3” means such form under the Securities Act as in effect on the date hereof or any
registration form under the Securities Act subsequently adopted by the SEC which permits inclusion or incorporation of substantial information by reference to other documents filed by the Company with the SEC. 

(f) The term “Holder” means any individual or entity owning or having the right to acquire Registrable
Securities or any assignee thereof in accordance with Section 1.11 hereof. 
 (g) The term “Major
Holder” means, other than Series C Investors who are not Existing Investors and Series B Investors who are not Existing Investors, each individual or entity owning at least 500,000 Registrable Securities (as adjusted for stock
splits, stock dividends, combinations and other recapitalizations), together with any of its general partners and affiliates. 

(h) The term “Majority Investors” means and includes Avalon Ventures IX, L.P. and each Permitted
Transferee thereof and MPM BioVentures V, L.P. and each Permitted Transferee thereof; provided, however, that to the extent that any of the foregoing entities 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. 
 (i) The term
“Permitted Transferee” has the meaning set forth in the Stockholders’ Agreement. 
 (j) The
term “Qualifying IPO” means the firmly underwritten initial public offering of shares of Common Stock at a per share price not less than three (3) times the Series B Original Purchase Price (as defined in the
Certificate of Incorporation and as adjusted for stock splits, stock dividends, combinations and other recapitalizations) resulting in proceeds to the Company of at least $40,000,000 (before deducting any underwriting or similar commissions,
compensation or concessions paid or allowed by the Company in connection with such offering and any expenses payable by the Company in connection with such offering). 

  
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 (k) The terms “register”,
“registered” and “registration” refer to a registration effected by preparing and filing a registration statement or similar document in compliance with the Securities Act, and the declaration or
ordering of effectiveness of such registration statement or document by the SEC. 
 (l) The term “Registrable
Securities” means all shares of Common Stock held by any Holder, including, but not limited to: (i) the Common Stock issuable or issued upon conversion of the Series C Preferred Stock, the Series B Preferred Stock, the
Series A Preferred Stock and the Series A-1 Preferred Stock; and (ii) any Common Stock of the Company issued as (or issuable upon the conversion or exercise of any warrant, right or other security which is issued as) a dividend or
other distribution with respect to, or in exchange for or in replacement of the shares referenced in clause “(i)” above, excluding in all cases, however, any Registrable Securities sold by a Holder in a transaction in which such
Holders’s rights under this Section 1 are not assigned and excluding Registrable Securities that have been sold in an offering registered under the Securities Act or in an open-market transaction under Rule 144 of the Securities Act.

 (m) The number of shares of “Registrable Securities then-outstanding” shall be determined by
the number of shares of Common Stock then-outstanding which are, and the number of shares of Common Stock issuable pursuant to then-exercisable or then-convertible securities which are, Registrable Securities. 

(n) The term “Registration Expenses” means all expenses incurred by the Company in complying with
Sections 1.2, 1.3 and 1.4 hereof, including, without limitation, all registration and filing fees, printing expenses, fees and disbursements of counsel for the Company, reasonable fees and disbursements of a single special counsel for the
Holders, blue sky fees and expenses and the expense of any special audits incident to or required by any such registration (but excluding the compensation of regular employees of the Company which shall be paid in any event by the Company).

 (o) The term “SEC” means the Securities and Exchange Commission. 

(p) The term “Securities Act” means the Securities Act of 1933, as amended. 

(q) The term “Selling Expenses” means all underwriting discounts and selling commissions applicable to a
sale of Registrable Securities. 
 (r) The term “Series A Directors” has the meaning set
forth in the Stockholders’ Agreement. 
 (s) The term “Series A Preferred Stock” means
the Series A Preferred Stock, par value $0.001 per share, of the Company. 
 (t) The term
“Series A-1 Preferred Stock” means the Series A-1 Preferred Stock, par value $0.001 per share, of the Company. 

  
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 (u) The term “Series B Preferred Stock” means the
Series B Preferred Stock, par value $0.001 per share, of the Company. 
 (v) The term “Series C
Preferred Stock” means the Series C Preferred Stock, par value $0.001 per share, of the Company. 
 (w)
The term “Stockholders’ Agreement” means the Second Amended and Restated Stockholders’ Agreement, dated the date hereof, by and among the Company and the stockholders named therein. 

1.2 Demand Registration. 
 (a) After the earlier of (i) five (5) years after the date of the Prior Agreement or (ii) six (6) months after the effective date of a Qualifying IPO, if the Company receives a
written request from the Holders of at least a majority of the Registrable Securities then- outstanding that the Company file a registration statement under the Securities Act (provided that the anticipated aggregate offering price would exceed
$5,000,000), then the Company shall: 
 (i) within thirty (30) days of the receipt thereof, give written notice of
such request to all Holders; and 
 (ii) use its best efforts to effect, as soon as practicable after receipt of such
request, the registration under the Securities Act of that number of Registrable Securities which the Holders requested to be registered, subject to the limitations of Section 1.2(b), within thirty (30) days of the mailing of such notice
by the Company. 
 (b) If the Holders initiating the registration request hereunder (the “Initiating
Holders”) intend to distribute the Registrable Securities covered by their request by means of an underwriting, they shall so advise the Company as a part of their request made pursuant to Section 1.2(a) and the Company shall
include such information in the written notice referred to in Section 1.2(a). In such event, the right of any Holder to include its Registrable Securities in such registration shall be conditioned upon such Holder’s participation in such
underwriting and the inclusion of such Holder’s Registrable Securities in the underwriting (unless otherwise mutually agreed by a majority in interest of the Initiating Holders and such Holder) to the extent provided herein. All Holders
proposing to distribute their securities through such underwriting shall (together with the Company as provided in Section 1.5(f)) enter into an underwriting agreement in customary form with the underwriter or underwriters selected for such
underwriting; provided, however, that no Holder (or any of their assignees) shall be required to make any representations, warranties or indemnities except as they relate to such Holder’s ownership of shares and authority to enter
into the underwriting agreement and to such Holder’s intended method of distribution, and the liability of such Holder shall be limited to an amount equal to the net proceeds from the offering received by such Holder. Notwithstanding any other
provision of this Section 1.2, if the underwriter advises the Initiating Holders in writing that marketing factors require a limitation of the number of shares to be underwritten, then the Initiating Holders shall so advise all Holders of
Registrable Securities which would otherwise be underwritten pursuant hereto, and the number of shares of Registrable Securities that may be included in the underwriting shall be allocated among all Holders thereof, including the Initiating

  
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Holders, in proportion (as nearly as practicable) to the amount of Registrable Securities of the Company owned by each Holder; provided, however, that the number of shares of
Registrable Securities to be included in such underwriting shall not be reduced unless all other securities are first entirely excluded from the underwriting. 
 (c) The Company shall not be obligated to effect, or to take any action to effect, any registration pursuant to this Section 1.2: 

(i) After the Company has effected two (2) registrations pursuant to this Section 1.2 and such registrations have been
declared or ordered effective; or 
 (ii) If the Company delivers notice to the Initiating Holders within thirty
(30) days of such Initiating Holders’ registration request that the Company intends to file the first registration statement for a public offering of securities of the Company (other than a registration statement relating either to the
sale of securities to employees of the Company pursuant to a stock option, stock purchase or similar plan or a transaction pursuant to Rule 145 of the Securities Act (“SEC Rule 145”)) within sixty (60) days
from the date of such notice. 
 1.3 Company Registration. 

(a) If (but without any obligation to do so) the Company proposes to register (including for this purpose a registration effected
by the Company for stockholders other than the Holders) any of its stock or other securities under the Securities Act in connection with the public offering of such securities solely for cash (other than a registration statement relating either to
the sale of securities to employees of the Company pursuant to a stock option, stock purchase or similar plan or an SEC Rule 145 transaction), the Company shall, at such time, promptly give each Holder written notice of such registration. Upon
the written request of each Holder given within twenty (20) days after mailing of such notice by the Company, the Company shall cause to be registered under the Securities Act all of the Registrable Securities that each such Holder has
requested to be registered. 
 (b) If the registration statement under which the Company gives notice under this
Section 1.3 is for an underwritten offering, the Company shall so advise the Holders of Registrable Securities. In such event, the right of any such Holder to be included in a registration pursuant to this Section 1.3 shall be conditioned
upon such Holder’s participation in such underwriting and the inclusion of such Holder’s Registrable Securities in the underwriting to the extent provided herein. All Holders proposing to distribute their Registrable Securities through
such underwriting shall enter into an underwriting agreement in customary form with the underwriter or underwriters selected for such underwriting by the Company; provided, however, that no Holder (or any of their assignees) shall be
required to make any representations, warranties or indemnities except as they relate to such Holder’s ownership of shares and authority to enter into the underwriting agreement and to such Holder’s intended method of distribution, and the
liability of such Holder shall be limited to an amount equal to the net proceeds from the offering received by such Holder. Notwithstanding any other provision of the Agreement, if the underwriter determines in good faith that marketing factors
require a limitation of the number of shares to be underwritten, the number of shares that may be included in the underwriting shall be allocated: (i) first, to the Company; (ii) second, to the Holders on a pro

  
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rata basis based on the total number of Registrable Securities held by the Holders; and (iii) third, to any stockholder of the Company (other than a Holder) on a pro rata basis. No such
reduction shall reduce the amount of securities of the selling Holders included in the registration below forty percent (40%) of the total amount of securities included in such registration, unless such offering is the Company’s initial
public offering of shares of Common Stock registered under the Securities Act and such registration does not include shares of any other selling stockholders, in which event any or all of the Registrable Securities of the Holders may be excluded in
accordance with the immediately preceding sentence at the underwriter’s discretion. In no event will shares of any other selling stockholder be included in such registration which would reduce the number of shares which may be included by
Holders without the written consent of Holders of not less than a majority of the Registrable Securities proposed to be sold in the offering. If any Holder disapproves of the terms of any such underwriting, such Holder may elect to withdraw
therefrom by written notice to the Company and the underwriter, delivered at least ten (10) business days prior to the effective date of the registration statement. Any Registrable Securities excluded or withdrawn from such underwriting shall
be excluded and withdrawn from the registration. For any Holder which is a partnership, limited liability company or corporation, the partners, retired partners, managers, members and stockholders of such Holder, or the estates and family members of
any such partners, members and retired partners and any trusts for the benefit of any of the foregoing persons shall be deemed to be a single “Holder”, and any pro rata reduction with respect to such “Holder” shall be based upon
the aggregate amount of shares carrying registration rights owned by all entities and individuals included in such “Holder”, as defined in this sentence. 
 1.4 Form S-3 Registration. In the event that the Company receives a written request from the Holders that the Company effect a registration on Form S-3 and any related qualification or compliance
with respect to all or a part of the Registrable Securities owned by such Holders, the Company will: 
 (a) promptly give
written notice of the proposed registration, and any related qualification or compliance, to all other Holders; and 
 (b)
as soon as practicable, effect such registration and all such qualifications and compliances as may be so requested and as would permit or facilitate the sale and distribution of all or such portion of such Holder’s or Holders’
Registrable Securities as are specified in such request, together with all or such portion of the Registrable Securities of any other Holder or Holders joining in such request as are specified in a written request given within fifteen (15) days
after receipt of such written notice from the Company; provided, however, that the Company shall not be obligated to effect any such registration, qualification or compliance, pursuant to this Section 1.4: (i) if Form S-3 is
not available for such offering by the Holders; (ii) if the Holders, together with the holders of any other securities of the Company entitled to inclusion in such registration, propose to sell Registrable Securities and such other securities
(if any) at an aggregate price to the public of less than $1,000,000; (iii) if the Company has, within the 12-month period preceding the date of such request, already effected two (2) registrations on Form S-3 for the Holders pursuant to
this Section 1.4; or (iv) in any particular jurisdiction in which the Company would be required to qualify to do business or to execute a general consent to service of process in effecting such registration, qualification or compliance.

  
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 (c) Subject to the foregoing, the Company shall file a Form S-3 registration
statement covering the Registrable Securities and other securities so requested to be registered as soon as practicable after receipt of the request or requests of the Holders. Registrations effected pursuant to this Section 1.4 shall not be
counted as demands for registration or registrations effected pursuant to Sections 1.2 or 1.3, respectively. 
 1.5
Obligations of the Company. Whenever required under this Section 1 to effect the registration of any Registrable Securities, the Company shall, as expeditiously as reasonably possible: 

(a) prepare and file with the SEC a registration statement with respect to such Registrable Securities, use its best efforts to
cause such registration statement to become effective, and, upon the request of the Holders of a majority of the Registrable Securities registered thereunder, keep such registration statement effective for a period of up to one (1) year or
until the distribution contemplated in the registration statement has been completed; provided, however, that: (i) such one (1) year period shall be extended for a period of time equal to the period any Holder refrains from
selling any securities included in such registration at the request of the Company or any underwriter for the Company; and (ii) in the case of any registration of Registrable Securities on Form S-3 which are intended to be offered on a
continuous or delayed basis, such one (1) year period shall be extended, if necessary, to keep the registration statement effective until all such Registrable Securities are sold; 

(b) prepare and file with the SEC such amendments and supplements to such registration statement and the prospectus used in
connection with such registration statement as may be necessary to comply with the provisions of the Securities Act with respect to the disposition of all securities covered by such registration statement; 

(c) furnish to the Holders such numbers of copies of a prospectus, including a preliminary prospectus, in conformity with the
requirements of the Securities Act, and such other documents as they may reasonably request in order to facilitate the disposition of Registrable Securities owned by them; 
 (d) use its best efforts to register and qualify the securities covered by such registration statement under such other securities or blue sky laws of such jurisdictions as shall be reasonably
requested by the Holders; provided, however, that the Company shall not be required in connection therewith or as a condition thereto to qualify to do business or to file a general consent to service of process in any such states or
jurisdictions, unless the Company is already subject to service in such jurisdiction and except as may be required by the Securities Act; 
 (e) in the event of any order suspending the effectiveness of a registration statement, use its best efforts to obtain the withdrawal of such order at the earliest possible time; 

(f) in the event of any underwritten public offering, enter into and perform its obligations under an underwriting agreement, in
usual and customary form, with the managing underwriter of such offering; 

  
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 (g) notify each Holder of Registrable Securities covered by a registration statement
at any time when a prospectus relating thereto is required to be delivered under the Securities Act of the happening of any event as a result of which the prospectus included in such registration statement, as then in effect, includes an untrue
statement of a material fact or omits to state a material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances then existing; 

(h) notify each Holder of Registrable Securities covered by a registration statement of: (i) the effectiveness of such
registration statement; (ii) the filing of any post- effective amendments to such registration statement; or (iii) the filing of a supplement to such registration statement; 

(i) make available for inspection, upon reasonable notice during the Company’s regular business hours, by each Holder of
Registrable Securities covered by a registration statement, any underwriter participating in any distribution pursuant to such registration statement, and any attorney, accountant or other agent retained by such Holder or underwriter, all material
financial and other records, pertinent corporate documents and properties of the Company, and cause the Company’s officers, directors and employees to supply all information reasonably requested by any such Holder, underwriter, attorney,
accountant or agent in connection with such registration statement; 
 (j) upon the transfer of shares by a Holder in
connection with a registration hereunder, furnish unlegended certificates representing ownership of the Registrable Securities being sought in such denominations as shall be requested by the Holders or the underwriters; 

(k) cause all such Registrable Securities registered pursuant hereunder to be listed on each securities exchange on which similar
securities issued by the Company are then listed; 
 (l) provide a transfer agent and registrar for all Registrable
Securities registered pursuant hereunder and a CUSIP number for all such Registrable Securities, in each case not later than the effective date of such registration; and 
 (m) furnish, at the request of any Holder, on the date that such Holder’s Registrable Securities are delivered to the underwriters for sale in connection with a registration pursuant to this
Agreement, if such securities are being sold through underwriters, or, if such securities are not being sold through underwriters, on the date that the registration statement with respect to such securities becomes effective: (i) an opinion,
dated as of such date, of the counsel representing the Company for the purposes of such registration, in form and substance as is customarily given to underwriters in an underwritten public offering and reasonably satisfactory to a majority in
interest of the Holders requesting registration, addressed to the underwriters and to the Holders requesting registration of Registrable Securities; and (ii) a “comfort” letter dated as of such date, from the independent certified
public accountants of the Company, in form and substance as is customarily given by independent certified public accountants to underwriters in an underwritten public offering and reasonably satisfactory to a majority in interest of the Holders
requesting registration, addressed to the underwriters and to the Holders requesting registration of Registrable Securities. 

  
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 1.6 Furnish Information. 

(a) It shall be a condition precedent to the obligations of the Company to take any action pursuant to this Section 1 with
respect to the Registrable Securities of any selling Holder that such Holder shall furnish to the Company such information regarding itself, the Registrable Securities held by it, and the intended method of disposition of such securities as shall be
required to effect the registration of such Holder’s Registrable Securities. For the avoidance of doubt, the Company shall be entitled to exclude from any registration the Registrable Securities of any selling Holder that does not comply with
the provisions of this Section 1.6(a). 
 (b) The Company shall have no obligation with respect to any registration
requested pursuant to Section 1.2 if, due to the operation of Section 1.6(a), the number of shares or the anticipated aggregate offering price of the Registrable Securities to be included in the registration does not equal or exceed the
number of shares or the anticipated aggregate offering price required to originally trigger the Company’s obligation to initiate such registration as specified in Section 1.2(a). 

1.7 Expenses of Registration. Except as specifically provided herein, all Registration Expenses incurred in connection with any
registration, qualification or compliance pursuant to Section 1.2, Section 1.3 or Section 1.4 herein shall be borne by the Company. All Selling Expenses incurred in connection with any registrations hereunder, shall be borne by the
holders of the securities so registered pro rata on the basis of the number of shares so registered. 
 1.8
Indemnification. In the event any Registrable Securities are included in a registration statement under this Section 1: 
 (a) To the extent permitted by law, the Company will indemnify and hold harmless each Holder, any underwriter (as defined in the Securities Act) for such Holder and each person, if any, who
controls such Holder or underwriter within the meaning of the Securities Act or the Exchange Act, against any losses, claims, damages, or liabilities (joint or several) to which they may become subject under the Securities Act, the Exchange Act or
other federal or state law, insofar as such losses, claims, damages, or liabilities (or actions in respect thereof) arise out of or are based upon any of the following statements, omissions or violations (collectively a
“Violation”): (i) any untrue statement or alleged untrue statement of a material fact contained in such registration statement, including any preliminary prospectus or final prospectus contained therein or any amendments
or supplements thereto; (ii) the omission or alleged omission to state therein a material fact required to be stated therein, or necessary to make the statements therein not misleading; or (iii) any violation or alleged violation by the
Company of the Securities Act, the Exchange Act, any state securities law or any rule or regulation promulgated under the Securities Act, the Exchange Act or any state securities law; and the Company will pay to each such Holder, underwriter or
controlling person any legal or other expenses reasonably incurred by them in connection with investigating or defending any such loss, claim, damage, liability, or action; provided, however, that the indemnity agreement

  
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contained in this Section 1.8(a) shall not apply to amounts paid in settlement of any such loss, claim, damage, liability, or action if such settlement is effected without the consent of the
Company (which consent shall not be unreasonably withheld), nor shall the Company be liable in any such case for any such loss, claim, damage, liability, or action to the extent that it arises out of or is based upon a Violation which occurs solely
in reliance upon and in conformity with written information furnished expressly for use in connection with such registration by any such Holder, underwriter or controlling person. 

(b) To the extent permitted by law, each selling Holder will, severally but not jointly, indemnify and hold harmless the Company,
each of its directors, each of its officers who has signed the registration statement, each person, if any, who controls the Company within the meaning of the Securities Act, any underwriter, any other Holder selling securities in such registration
statement and any controlling person of any such underwriter or other Holder, against any losses, claims, damages, or liabilities (joint or several) to which any of the foregoing persons may become subject, under the Securities Act, the Exchange Act
or other federal or state law, insofar as such losses, claims, damages, or liabilities (or actions in respect thereto) arise out of or are based upon any Violation, in each case to the extent (and only to the extent) that such Violation occurs
solely in reliance upon and in conformity with written information furnished by such Holder expressly for use in connection with such registration; and each such Holder will pay any legal or other expenses reasonably incurred by any person intended
to be indemnified pursuant to this Section 1.8(b), in connection with investigating or defending any such loss, claim, damage, liability, or action; provided, however, that the indemnity agreement contained in this
Section 1.8(b) shall not apply to amounts paid in settlement of any such loss, claim, damage, liability or action if such settlement is effected without the consent of the Holder, which consent shall not be unreasonably withheld; and
provided further that, in no event shall any indemnity under this Section 1.8(b) exceed the net proceeds from the offering received by such Holder. 
 (c) Promptly after receipt by an indemnified party under this Section 1.8 of notice of the commencement of any action (including any governmental action), such indemnified party will, if a
claim in respect thereof is to be made against any indemnifying party under this Section 1.8, deliver to the indemnifying party a written notice of the commencement thereof and the indemnifying party shall have the right to participate in, and,
to the extent the indemnifying party so desires, jointly with any other indemnifying party similarly noticed, to assume the defense thereof with counsel mutually satisfactory to the parties; provided, however, that an indemnified party
(together with all other indemnified parties which may be represented without conflict by one counsel) shall have the right to retain one separate counsel, with the fees and expenses to be paid by the indemnifying party, if representation of such
indemnified party by the counsel retained by the indemnifying party would be inappropriate due to actual or potential differing interests between such indemnified party and any other party represented by such counsel in such proceeding. The failure
to deliver written notice to the indemnifying party within a reasonable time of the commencement of any such action, if prejudicial to its ability to defend such action, shall relieve such indemnifying party of any liability to the indemnified party
under this Section 1.8, but the omission to deliver written notice to the indemnifying party will not relieve it of any liability that it may have to any indemnified party otherwise than under this Section 1.8. 

  
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 (d) If the indemnification provided for in this Section 1.8 is held by a court
of competent jurisdiction to be unavailable to an indemnified party with respect to any loss, liability, claim, damage, or expense referred to therein, then the indemnifying party, in lieu of indemnifying such indemnified party hereunder, shall
contribute to the amount paid or payable by such indemnified party as a result of such loss, liability, claim, damage, or expense in such proportion as is appropriate to reflect the relative fault of the indemnifying party on the one hand and of the
indemnified party on the other in connection with the statements or omissions that resulted in such loss, liability, claim, damage, or expense as well as any other relevant equitable considerations. The relative fault of the indemnifying party and
of the indemnified party shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission to state a material fact relates to information supplied by the indemnifying party or
by the indemnified party and the parties’ relative intent, knowledge, access to information, and opportunity to correct or prevent such statement or omission. 
 (e) Notwithstanding the foregoing, to the extent that the provisions relating to indemnification and contribution contained in the underwriting agreement entered into in connection with the
underwritten public offering are in conflict with the foregoing provisions, the provisions in the underwriting agreement shall control. 
 (f) The obligations of the Company and Holders under this Section 1.8 shall survive the completion of any offering of Registrable Securities in a registration statement under this
Section 1. 
 1.9 Reports Under the Exchange Act. With a view to making available to the Holders the benefits of
Rule 144 promulgated under the Securities Act (“SEC Rule 144”) and any other rule or regulation of the SEC that may at any time permit a Holder to sell securities of the Company to the public without registration or
pursuant to a registration on Form S-3, the Company agrees to: 
 (a) make and keep public information available, as
those terms are understood and defined in SEC Rule 144, at all times after ninety (90) days after the effective date of the first registration statement filed by the Company for the offering of its securities to the general public (other
than a registration statement relating either to the sale of securities to employees of the Company pursuant to a stock option, stock purchase or similar plan or an SEC Rule 145 transaction); 

(b) take such action, including the voluntary registration of its Common Stock under Section 12 of the Exchange Act, as is
necessary to enable the Holders to utilize Form S-3 for the sale of their Registrable Securities, such action to be taken as soon as practicable after the end of the fiscal year in which the first registration statement filed by the Company for the
offering of its securities to the general public (other than a registration statement relating either to the sale of securities to employees of the Company pursuant to a stock option, stock purchase or similar plan or an SEC Rule 145
transaction) is declared effective; 
 (c) file with the SEC in a timely manner all reports and other documents required
of the Company under the Securities Act and the Exchange Act; and 

  
 11 

 (d) furnish to any Holder, so long as the Holder owns any Registrable Securities,
forthwith upon request: (i) a written statement by the Company that it has complied with the reporting requirements of SEC Rule 144 (at any time after ninety (90) days after the effective date of the first registration statement filed
by the Company), the Securities Act and the Exchange Act (at any time after it has become subject to such reporting requirements), or that it qualifies as a registrant whose securities may be resold pursuant to Form S-3 (at any time after it so
qualifies); (ii) a copy of the most recent annual or quarterly report of the Company and such other reports and documents so filed by the Company; and (iii) such other information as may be reasonably requested in availing any Holder of
any rule or regulation of the SEC which permits the selling of any such securities without registration or pursuant to such form. 
 1.10 Limitation on Subsequent Registration Rights. After the date of this Agreement, the Company shall not, without the prior written consent of the Holders of at least a majority of the
Registrable Securities then-outstanding, enter into any agreement with any holder or prospective holder of any securities of the Company that would grant such holder registration rights pari passu or senior to those granted to the Holders
hereunder. 
 1.11 Assignment of Registration Rights. The rights to cause the Company to register Registrable Securities
pursuant to this Section 1 may be assigned (but only with all related obligations) by a Holder to one or more transferees or assignees of such securities (an “Assignee”): (i) to whom such Holder transfers such
securities pursuant to Section 3.2 hereof; (ii) who is an employee, affiliate or affiliated partnership managed by such Holder; or (iii) who, after such assignment or transfer, acquires at least ten percent (10%) (subject to
appropriate adjustment for stock splits, stock dividends, combinations and other recapitalizations) of the Registrable Securities held by the Holder as of the date of this Agreement, provided that (a) the Company is, within a reasonable time
after such transfer, furnished with written notice of the name and address of such Assignee and the securities with respect to which such registration rights are being assigned and (b) such Assignee agrees in writing to be bound by and subject
to the terms and conditions of this Agreement. 
 1.12 Termination of Registration Rights. No Holder shall be entitled to
exercise any right provided for in this Section 1 after five (5) years following the consummation of the sale of securities pursuant to a Qualifying IPO or, as to any Holder, such earlier time at which all Registrable Securities held by
such Holder (and any affiliate of the Holder with whom such Holder must aggregate its sales under SEC Rule 144) can be sold without restriction in any three (3) month period without registration in compliance with SEC Rule 144.

  

	2.	ADDITIONAL COVENANTS. 

2.1 Delivery of Financial Statements and Related Information. 

(a) The Company shall deliver, or make available on a secure password- protected website or otherwise, to each Major Holder, each
Series C Investor and each Series B Investor: 
 (i) as soon as practicable, but in any event within one
hundred twenty (120) days after the end of each fiscal year of the Company, an income statement for such fiscal 

  
 12 

 
year, a balance sheet of the Company and statement of stockholder’s equity as of the end of such year, and a schedule as to the sources and applications of funds for such year, such year-end
financial reports to be in reasonable detail, prepared in accordance with generally accepted accounting principles, and audited and certified by independent public accountants selected by the Company and approved by the Board of Directors; and

 (ii) as soon as practicable, but in any event within forty-five (45) days after the end of each quarter of each
fiscal year of the Company, an unaudited income statement for the relevant fiscal quarter, schedule as to the sources and application of funds for such fiscal quarter, and an unaudited balance sheet as of the end of such fiscal quarter, all prepared
in accordance with generally accepted accounting principles, except for any otherwise applicable footnote disclosures, and certified by the Company’s Chief Financial Officer (or person performing similar functions in the absence of a Chief
Financial Officer). 
 (b) The Company shall deliver, or make available on a secure password- protected website or
otherwise, to each Major Holder: 
 (i) as soon as practicable, but in any event within thirty (30) days prior to
the end of each fiscal year, a comprehensive operating budget approved by the Board of Directors, forecasting the Company’s revenues, expenses and cash position on a month-to-month basis for the upcoming fiscal year; 

(ii) as soon as practicable, but in any event within fifteen (15) days after the end of each quarter of each fiscal year of
the Company, a then current capitalization table of the Company certified by the Company’s Chief Financial Officer (or person performing similar functions in the absence of a Chief Financial Officer); and 

(iii) such other information relating to the financial condition, business, prospects or corporate affairs of the Company as
determined by the Board of Directors or as any such Major Holder may from time to time reasonably request. 
 (c)
Notwithstanding the foregoing, if the Board of Directors reasonably determines that the Company’s fulfillment of its obligations set forth in this Section 2.1 with respect to any specific Holder would be likely to result in a breach by
the Company of any non- disclosure obligation or other actual or potential conflict of interest, the Company shall have no obligation to such Holder with respect to this Section 2.1. 

2.2 Right of First Refusal. Subject to the terms and conditions specified in this Section 2.2, the Company hereby grants to
each Major Holder, each Series C Investor and each Series B Investor (collectively, the “ROFR Holders”) a right of first refusal with respect to future sales by the Company of Additional Shares of Common Stock (as
defined in the Certificate of Incorporation). Each Major Holder shall be entitled to apportion the right of first refusal hereby granted to it among itself and its partners and affiliates in such proportions as it deems appropriate. 

(a) Subject to Section 2.2(e), each time the Company proposes to offer any Additional Shares of Common Stock, the Company
shall first make an offering of such Additional Shares of Common Stock to each ROFR Holder in accordance with the following provisions: 
 (b) The Company shall deliver a notice in accordance with Section 4.3 below (the “Notice”) to each ROFR Holder stating: (i) its bona fide intention to offer such
Additional Shares of Common Stock; (ii) the number of such Additional Shares of Common Stock to be offered; and (iii) the price and terms, if any, upon which it proposes to offer such Additional Shares of Common Stock. 

  
 13 

 (c) Within seven (7) calendar days after delivery of the Notice in accordance
with Section 4.3 below, each ROFR Holder may elect to purchase or obtain, at the price and on the terms specified in the Notice, up to that portion of such Additional Shares of Common Stock which equals the proportion that the number of
Registrable Securities then held by such ROFR Holder bears to the total number of Registrable Securities then-outstanding. The Company shall promptly, in writing, inform each ROFR Holder that elects to purchase all of the Additional Shares of Common
Stock available to it (each, a “Participating ROFR Holder”) of any other ROFR Holder’s failure to do likewise. During the five (5) day period commencing after receipt of such notice, each Participating ROFR Holder
shall be entitled to obtain that portion of the Additional Shares of Common Stock for which ROFR Holders were entitled to, but did not, subscribe equal to the proportion that the number of Registrable Securities then held by such Participating ROFR
Holder bears to the total number of Registrable Securities then held by all Participating ROFR Holders who wish to purchase some of the unsubscribed Additional Shares of Common Stock. 

(d) If all Additional Shares of Common Stock that ROFR Holders are entitled to obtain pursuant to Section 2.2(b) are not
subscribed for as provided in Section 2.2(c), the Company may, during the sixty (60) day period following the expiration of the period provided in Section 2.2(c), offer the remaining unsubscribed portion of such Additional Shares of
Common Stock to any person or persons at a price not less than that, and upon terms no more favorable to such person or persons than those, specified in the Notice. If the Company does not enter into an agreement for the sale of the Additional
Shares of Common Stock within such period, or if such agreement is not consummated within thirty (30) days of the execution thereof, the right provided hereunder shall be deemed to be revived and such Additional Shares of Common Stock shall not
be offered unless first reoffered to the ROFR Holders in accordance herewith. 
 (e) The rights of first refusal of each
ROFR Holder under this Section 2.2 may be transferred to the same parties, subject to the same restrictions, as any transfer of registration rights pursuant to Section 1.11. 

2.3 Inspection Rights. Subject to the execution of reasonable nondisclosure agreements (if appropriate), each Major Holder shall
have the right to visit and inspect any of the properties of the Company, to discuss the affairs, finances and accounts of the Company with its officers, and to review such information as is reasonably requested all at such reasonable times (during
normal business hours) and as often as may be reasonably requested for any purpose reasonably related to such Major Holder’s interest as a stockholder of the Company; provided, however, that the Company shall not be obligated
under this Section 2.3 with respect to: (i) a 

  
 14 

 
competitor of the Company; (ii) information which the Board of Directors determines in good faith is confidential or attorney-client privileged and should not, therefore, be disclosed; or
(iii) any specific Holder if the Board of Directors reasonably determines that the Company’s fulfillment of its obligations set forth in this Section 2.3 with respect to such Holder would be disadvantageous to the Company, or be
likely to result in a breach by the Company of any non- disclosure obligation or other actual or potential conflict of interest. 
 2.4 D&O Insurance Coverage. The Company agrees to: (i) maintain a D&O insurance policy covering members of the Board of Directors (and their affiliated funds) and officers of the
Company in a reasonable amount satisfactory to the Majority Investors and on terms consistent with the NVCA VentureInsure product; and (ii) ensure that any successor of the Company or acquirer of all or substantially all of the Company’s
assets assumes the Company’s obligations with respect to indemnification of the members of the Board of Directors. 

2.5 Board of Directors Matters. Unless otherwise agreed by a majority of the members of the Board of Directors, including a
majority of the Series A Directors, meetings of the Board of Directors shall be held at least bimonthly. The Company shall reimburse all members of the Board of Directors for all reasonable travel expenses incurred by them in connection with
the attendance of meetings of the Board of Directors. 
 2.6 Employee Stock. Unless otherwise approved by the Board of
Directors, all recipients of options to purchase shares of the Company’s capital stock or similar equity awards after the date hereof shall be required to execute option agreements providing for vesting of shares over a four (4) year
period, with the first twenty-five percent (25%) of such shares vesting following twelve (12) months of continued employment, and the remaining shares vesting in equal monthly installments over the following thirty-six (36) months.

 2.7 Termination of Certain Covenants. The covenants set forth in this Section 2 shall terminate and be of no
further force or effect upon the earlier of: (i) the consummation of the sale of securities pursuant to a Qualifying IPO; or (ii) the first date upon which none of the Registrable Securities are outstanding. 

 

	3.	RESTRICTIONS ON TRANSFER. 

3.1 General Restrictions. In addition to any restrictions set forth in the Stockholders’ Agreement, each Holder agrees not to
make any disposition of all or any portion of its Registrable Securities unless and until: 
 (a) There is then in effect
a registration statement under the Securities Act covering such proposed disposition and such disposition is made in accordance with such registration statement; or 
 (b) (i) The transferee has agreed in writing to be bound by the terms of this Agreement; (ii) such Holder shall have notified the Company of the proposed disposition and shall have
furnished the Company with a detailed statement of the circumstances surrounding the proposed disposition; and (iii) if reasonably requested by the Company, such Holder shall have furnished the Company with an opinion of counsel, reasonably
satisfactory to the Company, that such disposition will not require registration of such shares under the Securities Act. 

  
 15 

 3.2 Exceptions. Notwithstanding the provisions of Section 3.1, no such
restriction shall apply to a transfer by a Holder that is: (i) a partnership transferring to its partners or former partners in accordance with partnership interests; (ii) a corporation transferring to a wholly owned subsidiary or a parent
corporation that owns all of the capital stock of the Holder; (iii) a limited liability company transferring to its members or former members in accordance with their interest in the limited liability company; (iv) an individual
transferring to the Holder’s family member or trust for the benefit of an individual Holder or such Holder’s family member(s); (v) the Kansas Bioscience Authority (or its successor or replacement entity), to any successor or
replacement entity formed by or as an instrumentality or authority of the State of Kansas; or (vi) 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; provided, however, that in each case the transferee will agree in
writing to be subject to the terms of this Agreement to the same extent as if he, she or it were an original Holder hereunder. 

3.3 Legends. Each certificate representing Registrable Securities shall be stamped or otherwise imprinted with a legend
substantially similar to the following (in addition to any legend required under applicable state securities laws): 
 THE SALE,
PLEDGE, HYPOTHECATION OR TRANSFER OF THE SECURITIES REPRESENTED BY THIS CERTIFICATE IS SUBJECT TO THE TERMS AND CONDITIONS OF THAT CERTAIN INVESTORS’ RIGHTS AGREEMENT BY AND BETWEEN THE STOCKHOLDER AND THE COMPANY. COPIES OF SUCH AGREEMENT MAY
BE OBTAINED UPON WRITTEN REQUEST TO THE SECRETARY OF THE COMPANY. 
 3.4 Removal of Legends. The Company shall be
obligated to promptly reissue unlegended certificates at the request of any Holder thereof if the Company has completed the initial public offering of shares of Common Stock registered under the Securities Act and the Holder shall have obtained an
opinion of counsel (which counsel may be counsel to the Company) reasonably acceptable to the Company to the effect that the securities proposed to be disposed of may lawfully be so disposed of without registration, qualification and legend. In
addition, any legend endorsed on an instrument pursuant to applicable state securities laws and the stop-transfer instructions with respect to such securities shall be removed upon receipt by the Company of an order of the appropriate blue sky
authority authorizing such removal. 
  

	4.	MISCELLANEOUS. 

 4.1
Successors and Assigns. Except as otherwise provided herein, the terms and conditions of this Agreement shall inure to the benefit of and be binding upon the respective successors and assigns of the parties (including transferees of any shares
of Registrable Securities). Nothing in this Agreement, express or implied, is intended to confer upon any party 

  
 16 

 
other than the parties hereto or their respective successors and assigns any rights, remedies, obligations, or liabilities under or by reason of this Agreement, except as expressly provided in
this Agreement. 
 4.2 Aggregation of Stock. All shares of Registrable Securities held or acquired by affiliated entities
or persons shall be aggregated together for the purpose of determining the availability of any rights under this Agreement. 

4.3 Notices. All notices required or permitted hereunder 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 or, 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 verification of receipt. All
communications shall be sent to the Company and to each of the Investors, as applicable, at the respective addresses set forth on the signature page of this document or at such other address(es) as the Company or any such Investor may designate by
ten (10) days advance written notice to the other parties hereto. 
 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 Amendments and Waivers. Any term of this Agreement may be amended and the observance of any term of this 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. Notwithstanding the foregoing: (i) 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 Investor without the written consent of such Investor unless such amendment, termination or waiver applies to all Investors in the same
fashion; (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, Series B Preferred Stock or Series A Preferred Stock as
“Investors” hereunder; and (iii) the provisions of Section 2.2 may not be waived in respect of any transaction in which any Majority Investor (or an affiliate thereof) purchases securities of the Company unless each ROFR Holder
is given the right to purchase securities on a pro rata basis with such Majority Investor (including its affiliates), which right may be exercisable on reasonable notice in a subsequent closing occurring after the initial purchase of securities in
such transaction. Any amendment or waiver effected in accordance with this paragraph shall be binding upon each holder of any Registrable Securities then-outstanding, each future holder of all such Registrable Securities, and the Company.

 4.6 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. 

  
 17 

 4.7 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. 
 4.8
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. 
 4.9 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] 

  
 18 

 IN WITNESS WHEREOF, the parties have executed this SECOND AMENDED AND RESTATED
INVESTORS’ RIGHTS 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

  
 [SIGNATURE
PAGE TO SECOND AMENDED AND 
 RESTATED INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	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
	
	INVESTOR:
	
	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 INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	 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
	
	INVESTOR:
	
	 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
	
	INVESTOR:
	
	 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 INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	 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
	
	INVESTOR:
	
	 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 INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	 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
	
	INVESTOR:
	
	 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
	
	INVESTOR:
	
	  

	(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

  
 [SIGNATURE
PAGE TO 
 SECOND AMENDED AND RESTATED INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	  

	(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
	
	INVESTOR:
	
	 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
	
	INVESTOR:
	
	  

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

	(signature)
		
	Print Name:	 	 David Frantze

	Title:	 	  

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

  
 [SIGNATURE
PAGE TO 
 SECOND AMENDED AND RESTATED INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	  

	(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
	
	INVESTOR:
	
	  

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

	(signature)
		
	Print Name:	 	 John Neil

	Title:	 	  

	(if applicable)
		
	Address:	 	7445 East Butler Drive
		 	Scottsdale, AZ 85258
	
	INVESTOR:
	
	  

	(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

  
 [SIGNATURE
PAGE TO 
 SECOND AMENDED AND RESTATED INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	  

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

	(signature)
		
	Print Name:	 	 Chris McGrath

	Title:	 	  

	(if applicable)
		
	Address:	 	5078 Seashell Place
		 	San Diego, CA 92130
	
	INVESTOR:
	
	 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
	
	INVESTOR:
	
	 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 INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	 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
	
	INVESTOR:
	
	 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
	
	INVESTOR:
	
	  

	(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 INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	  

	(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
	
	INVESTOR:
	
	  

	(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
	
	INVESTOR:
	
	  

	(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 INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	  

	(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
	
	INVESTOR:
	
	  

	(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
	
	INVESTOR:
	
	 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 INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	  

	(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

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED INVESTOR’S RIGHTS AGREEMENTS] 

 
			
	INVESTOR:
	
	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 INVESTORS’ RIGHTS AGREEMENT] 

 
			
	INVESTOR:
	
	  

	(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 INVESTORS’ RIGHTS AGREEMENT] 

 
			
	INVESTOR:
	
	 UMB Bank, n.a, As Custodian For The Sheila Kemder 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 INVESTORS’ RIGHTS AGREEMENT] 

 
			
	INVESTOR:
	
	 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. Floor 37

	 Boston, MA 02110

	  

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT] 

 
			
	INVESTOR:
	
	 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 INVESTORS’ RIGHTS AGREEMENT] 

 
			
	INVESTOR:
	
	  

	(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 INVESTORS’ RIGHTS AGREEMENT] 

 
			
	INVESTOR:
	
	 Christena A. Gautreaux Trust 2004

	(entity name if applicable)
		
	By:	 	   /s/ Christena A. Gautreaux

		 	(signature)

 
			
	Print Name:	 	   Christena A.
Gautreaux

 
			
	Title:	 	   Trustee

		 	(if applicable)
	
	Address:
	 200 west 54th St.

	 Kansas City MO. 64112

	  

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT] 

 
			
	INVESTOR:
	
	  

	(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 INVESTORS’ RIGHTS AGREEMENT] 

 
			
	INVESTOR:
	
	  

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

		 	(signature)
	Print Name	 	   Julia Stephanus

	Title:	 	    Chief Commercial Officer

		 	(if applicable)
	
	Address:
	 21 Tolmadge Lane

	 Basking Ridge NJ 07920

	  

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT] 

 
			
	INVESTOR:
	
	  

	(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 INVESTORS’ RIGHTS AGREEMENT] 

 
			
	INVESTOR:
	
	  

	(entity name if applicable)
		
	By:	 	   /s/ John Fulton Murray III

		 	(signature)
	Print Name	 	   John Fulton Murray III

	Title:	 	  

		 	(if applicable)
	
	Address:
	 1 Westover Rd.

	 Fort Worth, TX 76107

	  

 [SIGNATURE PAGE TO 
 SECOND AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT] 

 EXHIBIT A 
 SCHEDULE OF INVESTORS 
 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 

RaQualia Pharma Inc. 
 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 
 Davfd W. Frantze 

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

Christopher H. McGrath 

 Kansas Center for Entrepreneurship, Inc. 
 William Gautreaux 
 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 
 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 

 AMENDMENT NO. 1 TO 

SECOND AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT 

This Amendment No. l to Second Amended and Restated Investors’ Rights Agreement, dated as of May 22, 2013 (this
“Amendment”), by and among Aratana Therapeutics, Inc., a Delaware corporation (the “Company”), and 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 hereto (the “Other Investors,” and 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 Investors’ Rights 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
(as defined in the Agreement); provided, however, that notwithstanding the foregoing: (i) the Agreement may not be amended or terminated and the observance of any term of the Agreement may not be waived with respect to any Investor
without the written consent of such Investor unless such amendment, termination or waiver applies to all Investors in the same fashion; and (ii) the provisions of Section 2.2 of the Agreement may not be waived in respect of any transaction
in which any Majority Investor (or an affiliate thereof) purchases securities of the Company unless each ROFR Holder is given the right to purchase securities on a pro rata basis with such Majority Investor (including its affiliates), which right
may be exercisable on reasonable notice in a subsequent closing occurring after the initial purchase of securities in such transaction. 
 NOW, THEREFORE, in consideration of the promises and the mutual covenants and agreements contained herein and in the Investors’ Rights Agreement, the parties hereby agree as follows: 

Section 1. Amendments. 
 (a) Section 1.1(j) of the Agreement is hereby amended and restated in its entirety to read as follows: 
 “The term “Qualifying IPO” means a firmly underwritten initial public offering of shares of Common Stock (i) at a per share price not less than three (3) times the Series B
Original Purchase Price (as defined in the Certificate of Incorporation and as adjusted for stock splits, stock dividends, combinations and other recapitalizations) resulting in proceeds to the Company of at least $40,000,000 (before deducting any
underwriting or similar commissions, compensation or concessions paid or allowed by the Company in connection with such offering and any expenses payable by the Company in connection with such offering) or (ii) in connection with which each
share of Series A Preferred Stock, Series A-1 Preferred Stock, Series B Preferred Stock and Series C Preferred Stock shall automatically be converted into shares of Common Stock pursuant to Section IV.C.4(b)(i)(x) of the Company’s certificate
of incorporation.” 

 (b) Section 1.1(1) of the Agreement is hereby amended and restated in its entirety to read
as follows: 
 “The term “Registrable Securities” means all shares of Common Stock held by any Investor or
any assignee thereof in accordance with Section 1.11 hereof, including, but not limited to: (i) the Common Stock issuable or issued upon conversion of the Series C Preferred Stock, the Series B Preferred Stock, the Series A Preferred Stock and the
Series A-1 Preferred Stock; and (ii) any Common Stock of the Company issued as (or issuable upon the conversion or exercise of any warrant, right or other security which is issued as) a dividend or other distribution with respect to, or in exchange
for or in replacement of the shares referenced in clause “(i)” above, excluding in all cases, however, any Registrable Securities sold in a transaction in which the transferor’s rights under this Section 1 are not assigned and
excluding Registrable Securities that have been sold in an offering registered under the Securities Act or in an open-market transaction under Rule 144 of the Securities Act.” 

(c) The first sentence of Section 1.3(a) of the Agreement is hereby amended and restated in its entirety to read as follows:

 “If (but without any obligation to do so) the Company proposes to register (including for this purpose a registration
effected by the Company for stockholders other than the Holders) any of its stock or other securities under the Securities Act in connection with the public offering of such securities solely for cash (other than (i) a registration statement
relating either to the sale of securities to employees of the Company pursuant to a stock option, stock purchase or similar plan or an SEC Rule 145 transaction and (ii) the registration statement on Form S-1 (Reg. No. 333-187372) and any
related registration statement under Rule 462(b) promulgated under the Securities Act), the Company shall, at such time, promptly give each Holder written notice of such registration.” 

(d) The following text shall be added after Section 1.3(b) of the Agreement as a new Section 1.3(c): 

“(c) Notwithstanding the foregoing paragraphs (a) and (b), the provisions of this Section 1.3 shall not apply to the public
offering of the Company’s stock pursuant to the registration statement on Form S-1 (Reg. No. 333-187372) and any related registration statement under Rule 462(b) promulgated under the Securities Act, including the obligation of the Company
to provide notice of any registration in connection therewith.” 
 (e) The following text shall be added after
Section 2.2(e) of the Agreement as a new Section 2.2(f): 
 “(f) Notwithstanding anything to the contrary herein,
this Section 2.2 shall not apply to any sales by the Company of Additional Shares of Common Stock that are made in a Qualifying IPO.” 
 (f) The second sentence of Section 4.5 of the Agreement is hereby amended and restated in its entirety to read as follows: 
 “Notwithstanding the foregoing: (i) 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 Investor without the
written consent of such Investor unless such amendment, termination or waiver applies to all Investors in the same fashion; (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, Series B Preferred Stock or Series A Preferred Stock as “Investors” hereunder; and (iii) the provisions of Section 2.2 may not be waived in respect of any transaction in which
any Majority Investor (or an affiliate thereof) purchases securities of the Company, other than a Qualifying IPO, unless each ROFR Holder is given the right to purchase securities on a pro rata basis with such Majority Investor (including its
affiliates), which right may be exercisable on reasonable notice in a subsequent closing occurring after the initial purchase of securities in such transaction.” 

  
 2 

 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] 

  
 3 

 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 Investors’ Rights
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 Investors’ Rights
Agreement

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