Exhibit 10.66

SECOND AMENDMENT TO CREDIT AGREEMENT

This Second Amendment to Credit Agreement, dated as of December 17, 2018 (this
"Amendment"), is among HESKA CORPORATION, DIAMOND ANIMAL HEALTH, INC. and HESKA
IMAGING, LLC (the “Borrowers”), the other Loan Parties party hereto, the Lenders
party hereto, and JPMORGAN CHASE BANK, N.A., as Administrative Agent (in such
capacity, the “Administrative Agent”).

RECITAL

The Borrower, any other Loan Parties party thereto, the Lenders party thereto
and the Administrative Agent are parties to a Credit Agreement dated as of July
27, 2017 (as it may be amended or modified from time to time, the “Credit
Agreement”). The Borrowers desire to amend the Credit Agreement as set forth
herein and the Lenders are willing to do so in accordance with the terms hereof.

TERMS

In consideration of the premises and of the mutual agreements herein contained,
the parties agree as follows:
1.    ARTICLE 1.
AMENDMENTS.

Upon the satisfaction of the conditions set forth in Article 3 hereof, the
Credit Agreement shall be amended as follows:

1.1    The following new definition is added to Section 1.01 of the Credit
Agreement:

“Cuattro Acquisition” means acquisition of certain assets by Heska Imaging, LLC
(“Heska Imaging”) under the Purchase Agreement for Certain Assets with Cuattro,
LLC (“Cuattro”), pursuant to which Heska Imaging will purchase certain software
and related assets for an aggregate purchase price of approximately $8,200,000
(consisting of $2,750,000 in cash and 54,763 shares of the Borrower’s common
stock, $0.01 par value per share) and terminate its existing license of the
software assets and certain related rights and obligations in connection
therewith, all on the terms as described in the Borrower’s Form 8-K filed with
the SEC on November 26, 2018 and the Purchase Agreement filed therewith (and
without any material variation from those terms unless agreed to in writing by
the Administrative Agent).

1.2    The following new Section 1.07 is added to the Credit Agreement:

SECTION 1.07.     Interest Rates; LIBOR Notification. The interest rate on
Eurodollar Loans is determined by reference to the LIBO Rate, which is derived
from the London interbank offered rate. The London interbank offered rate is
intended to represent the rate at which contributing banks may obtain short-term
borrowings from each other in the London interbank market. In July 2017, the
U.K. Financial Conduct Authority announced that, after the end of 2021, it would
no longer persuade or compel contributing banks to make rate submissions to the
ICE Benchmark Administration (together with any successor to the ICE Benchmark
Administrator, the “IBA”) for purposes of the IBA setting the London interbank
offered rate. As a result, it is possible that commencing in 2022, the London
interbank offered rate may no longer be available or may no longer be deemed an
appropriate reference rate upon which to determine the interest rate on
Eurodollar Loans. In light of this eventuality, public and private sector
industry initiatives are currently underway to identify new or alternative
reference rates to be used in

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place of the London interbank offered rate. In the event that the London
interbank offered rate is no longer available or in certain other circumstances
as set forth in Section 2.14(c) of this Agreement, such Section 2.14(c) provides
a mechanism for determining an alternative rate of interest. The Administrative
Agent will notify the Borrower, pursuant to Section 2.14, in advance of any
change to the reference rate upon which the interest rate on Eurodollar Loans is
based. However, the Administrative Agent does not warrant or accept any
responsibility for, and shall not have any liability with respect to, the
administration, submission or any other matter related to the London interbank
offered rate or other rates in the definition of “LIBO Rate” or with respect to
any alternative or successor rate thereto, or replacement rate thereof,
including without limitation, whether the composition or characteristics of any
such alternative, successor or replacement reference rate, as it may or may not
be adjusted pursuant to Section 2.14(c), will be similar to, or produce the same
value or economic equivalence of, the LIBO Rate or have the same volume or
liquidity as did the London interbank offered rate prior to its discontinuance
or unavailability.

1.3    Section 2.14 of the Credit Agreement is restated as follows:

SECTION 2.14. Alternate Rate of Interest; Illegality.

(a)If prior to the commencement of any Interest Period for a Eurodollar
Borrowing:

(i)the Administrative Agent determines (which determination shall be conclusive
and binding absent manifest error) that adequate and reasonable means do not
exist for ascertaining the Adjusted LIBO Rate or the LIBO Rate, as applicable
(including, without limitation, by means of an Interpolated Rate or because the
LIBO Screen Rate is not available or published on a current basis) for such
Interest Period; or

(ii)the Administrative Agent is advised by the Required Lenders that the
Adjusted LIBO Rate or the LIBO Rate, as applicable, for such Interest Period
will not adequately and fairly reflect the cost to such Lenders (or Lender) of
making or maintaining their Loans (or Loan) included in such Borrowing for such
Interest Period;

then the Administrative Agent shall give notice thereof to the Borrower
Representative and the Lenders through Electronic System as provided in Section
9.01 as promptly as practicable thereafter and, until the Administrative Agent
notifies the Borrower Representative and the Lenders that the circumstances
giving rise to such notice no longer exist, (A) any Interest Election Request
that requests the conversion of any Borrowing to, or continuation of any
Borrowing as, a Eurodollar Borrowing shall be ineffective, and any such
Eurodollar Borrowing shall be repaid or converted into a CBFR Borrowing on the
last day of the then current Interest Period applicable thereto, and (B) if any
Borrowing Request requests a Eurodollar Borrowing, such Borrowing shall be made
as a CBFR Borrowing.

(b)If any Lender determines that any Requirement of Law has made it unlawful, or
if any Governmental Authority has asserted that it is unlawful, for any Lender
or its applicable lending office to make, maintain, fund or continue any
Eurodollar Borrowing, or any Governmental Authority has imposed material
restrictions on the authority of such Lender to purchase or sell, or to take
deposits of, dollars in the London interbank market, then, on notice thereof by
such Lender to the Borrower Representative through the Administrative Agent, any
obligations of such Lender to make, maintain, fund or continue Eurodollar Loans
or to convert CBFR Borrowings to Eurodollar Borrowings will be suspended until
such Lender notifies the Administrative Agent and the Borrower Representative
that the circumstances giving rise to such determination no longer exist. Upon
receipt of such notice, the Borrowers will upon demand from such Lender (with a
copy to the Administrative Agent), either prepay or convert all Eurodollar
Borrowings of

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such Lender to CBFR Borrowings, either on the last day of the Interest Period
therefor, if such Lender may lawfully continue to maintain such Eurodollar
Borrowings to such day, or immediately, if such Lender may not lawfully continue
to maintain such Loans. Upon any such prepayment or conversion, the Borrowers
will also pay accrued interest on the amount so prepaid or converted.

(c)If at any time the Administrative Agent determines (which determination shall
be conclusive absent manifest error) that (i) the circumstances set forth in
clause (a)(i) have arisen and such circumstances are unlikely to be temporary or
(ii) the circumstances set forth in clause (a)(i) have not arisen but either (w)
the supervisor for the administrator of the LIBO Screen Rate has made a public
statement that the administrator of the LIBO Screen Rate is insolvent (and there
is no successor administrator that will continue publication of the LIBO Screen
Rate), (x) the administrator of the LIBO Screen Rate has made a public statement
identifying a specific date after which the LIBO Screen Rate will permanently or
indefinitely cease to be published by it (and there is no successor
administrator that will continue publication of the LIBO Screen Rate), (y) the
supervisor for the administrator of the LIBO Screen Rate has made a public
statement identifying a specific date after which the LIBO Screen Rate will
permanently or indefinitely cease to be published or (z) the supervisor for the
administrator of the LIBO Screen Rate or a Governmental Authority having
jurisdiction over the Administrative Agent has made a public statement
identifying a specific date after which the LIBO Screen Rate may no longer be
used for determining interest rates for loans, then the Administrative Agent and
the Borrower Representative shall endeavor to establish an alternate rate of
interest to the LIBO Rate that gives due consideration to the then prevailing
market convention for determining a rate of interest for syndicated loans in the
United States at such time, and shall enter into an amendment to this Agreement
to reflect such alternate rate of interest and such other related changes to
this Agreement as may be applicable (but, for the avoidance of doubt, such
related changes shall not include a reduction of the Applicable Rate).
Notwithstanding anything to the contrary in Section 9.02, such amendment shall
become effective without any further action or consent of any other party to
this Agreement so long as the Administrative Agent shall not have received,
within five Business Days of the date notice of such alternate rate of interest
is provided to the Lenders, a written notice from the Required Lenders stating
that such Required Lenders object to such amendment. Until an alternate rate of
interest shall be determined in accordance with this clause (c) (but, in the
case of the circumstances described in clause (ii)(w), clause (ii)(x) or clause
(ii)(y) of the first sentence of this Section 2.14(c), only to the extent the
LIBO Screen Rate for such Interest Period is not available or published at such
time on a current basis), (x) any Interest Election Request that requests the
conversion of any Borrowing to, or continuation of any Borrowing as, a
Eurodollar Borrowing shall be ineffective and any such Eurodollar Borrowing
shall be repaid or converted into CBFR Borrowing on the last day of the then
current Interest Period applicable thereto, and (y) if any Borrowing Request
requests a Eurodollar Borrowing, such Borrowing shall be made as a CBFR
Borrowing; provided that, if such alternate rate of interest shall be less than
zero, such rate shall be deemed to be zero for the purposes of this Agreement.

1.4    Section 6.04(b) of the Credit Agreement is restated as follows:

(b)    (i) Permitted Acquisitions and (ii) if no Default exists at the time of
or would be caused thereby, the Cuattro Acquisition;

1.5    The following is added to the end of Section 6.09 of the Credit
Agreement: “and (j) the Cuattro Acquisition.”
    
ARTICLE 2.
REPRESENTATIONS.

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In order to induce the Lenders and the Administrative Agent to enter into this
Amendment, each Loan Party represents and warrants to each Lender and the
Administrative Agent, that the following statements are true, correct and
complete:

2.1    The execution, delivery and performance of this Amendment are within its
powers and have been duly authorized by it.

2.2    This Amendment is the legal, valid and binding obligation of it,
enforceable against it in accordance with the terms hereof, subject to
applicable bankruptcy, insolvency, reorganization, moratorium or other laws
affecting creditors' rights generally and subject to general principles of
equity, regardless of whether considered in a proceeding in equity or at law.

2.3    After giving effect to the amendments herein contained, the
representations and warranties contained in the Credit Agreement and the
representations and warranties contained in the other Loan Documents are true in
all material respects on and as of the date hereof with the same force and
effect as if made on and as of the date hereof (or, if any such representation
or warranty is expressly stated to have been made as of a specific date, as of
such specific date), and no Default exists or has occurred and is continuing on
the date hereof.

ARTICLE 3.
CONDITIONS PRECEDENT.

This Amendment shall be effective as of the date hereof when each of the
following conditions is satisfied or waived by the Administrative Agent:

3.1    This Amendment shall be executed by each of the Loan Parties and the
Lenders.

3.2    The Loan Parties shall satisfied such other conditions, if any, as
required in writing by the Administrative Agent.

2.    ARTICLE 4.
MISCELLANEOUS.

4.1    References in the Loan Documents to the Credit Agreement shall be deemed
to be references to the Credit Agreement as amended hereby and as further
amended from time to time. This Agreement is a Loan Document. Terms used but not
defined herein shall have the respective meanings ascribed thereto in the Credit
Agreement. This Amendment is a Loan Document. This Agreement may be signed upon
any number of counterparts with the same effect as if the signatures thereto and
hereto were upon the same instrument and signatures sent by facsimile or other
electronic imaging shall be enforceable as originals.

4.2    Except as expressly amended hereby, each Loan Party agrees that the Loan
Documents are ratified and confirmed and shall remain in full force and effect
and that it has no set off, counterclaim, defense or other claim or dispute with
respect to any of the foregoing. The Loan Parties acknowledge and agree that all
Secured Obligations are unconditionally owing by the Loan Parties and their
applicable Subsidiaries without setoff, recoupment, defense, or counterclaim, in
law or in equity, of any kind or character, and all Secured Obligations are and
will continue to be secured by valid, perfected, indefeasible Liens in, among
other things, the Collateral under the Loan Documents, and each of the Loan
Parties reaffirms its obligations and duties under the Loan Documents and the
Liens in the Collateral that it granted to Administrative Agent under the Loan
Documents to secure the Secured Obligations.

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IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly
executed by their respective authorized officers as of the day and year first
above written.

HESKA CORPORATION

By: /s/ Catherine Grassman
Name: Catherine Grassman
Title: VP, Chief Accounting Officer and Controller

DIAMOND ANIMAL HEALTH, INC.

By: /s/ Catherine Grassman
Name: Catherine Grassman
Title: VP, Chief Financial Officer and Treasurer

HESKA IMAGING, LLC

By: /s/ Catherine Grassman
Name: Catherine Grassman
Title: VP, Chief Financial Officer

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JPMORGAN CHASE BANK, N.A., as a Lender, and as Administrative Agent, Swingline
Lender and Issuing Bank

By: /s/ Michele Liby
Name: Michele Liby
Title: Authorized Signer

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