Exhibit 10.1

[***]     – Certain information in this exhibit have been omitted and filed
separately with the Securities and Exchange Commission. Confidential treatment
has been requested with respect to the omitted portions.

EIGHTH AMENDMENT TO SECOND AMENDED AND RESTATED
CREDIT AND SECURITY AGREEMENT

                This Amendment, dated as of March 22, 2005, is made by and
between Heska Corporation, a Delaware corporation (“Heska”), Diamond Animal
Health, Inc., an Iowa corporation (“Diamond”) (each of Heska and Diamond may be
referred to herein individually as a “Borrower” and collectively as the
“Borrowers”), and Wells Fargo Business Credit, Inc., a Minnesota corporation
(the “Lender”).

Recitals

                The Borrowers and the Lender are parties to a Second Amended and
Restated Credit and Security Agreement dated as of June 14, 2000 (as amended to
date and as the same may be hereafter amended from time to time, the “Credit
Agreement”). Capitalized terms used in these recitals have the meanings given to
them in the Credit Agreement unless otherwise specified.

                The Borrowers have requested that certain amendments be made to
the Credit Agreement, which the Lender is willing to make pursuant to the terms
and conditions set forth herein.

                NOW, THEREFORE, in consideration of the premises and of the
mutual covenants and agreements herein contained, it is agreed as follows:

               1.        Defined Terms.  Capitalized terms used in this
Amendment which are defined in the Credit Agreement shall have the same meanings
as defined therein, unless otherwise defined herein.

               2.         Spread.  Section 2.7 of the Credit Agreement is
amended to read in its entirety as follows:

         “Section 2.7 Spread.  The spread (the “Spread”) means two and
three-quarters percent (2.75%), effective retroactive to January 1, 2005;
provided, however, that (a) if on the last day of any month, Permanent Capital
exceeds the Minimum Capital covenant for such month set forth in Section 6.12 by
[***] or more, “Spread” shall be set to one and three-quarters percent (1.75%),
effective as of the first day of the month following such achievement; and
provided further that if on the last day of any month, Permanent Capital does
not exceed the Minimum Capital covenant for such month by [***] or more,
“Spread” shall be set to two and three-quarters percent (2.75%), effective as of
the first day of the month following such a situation; and (b) if [***] in
respect of the Borrower’s current dispute with that company relating to invoices
totaling approximately $329,000, then “Spread” shall mean 2.5% or 1.5% for all
periods instead of 2.75% or 1.75%, respectively, effective as of the first day
of the month following the month in

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[***]     – Certain information on this page have been omitted and filed
separately with the Securities and Exchange Commission. Confidential treatment
has been requested with respect to the omitted portions.

  which the Borrower delivers to the Lender evidence of such collection, if such
evidence is acceptable to the Lender in its sole discretion.”

               3.        Minimum Net Income.  Section 6.13 of the Credit
Agreement is hereby amended to read in its entirety as follows:

        “Section 6.13 Minimum Net Income.  Heska will achieve, on a consolidated
basis, during each period described below, Net Income in an amount not less than
the amount set forth opposite such period (amounts in parentheses denote
negative numbers):

  Period
Twelve months ended December 31, 2004
Three months ending March 31, 2005
Six months ending June 30, 2005
Nine months ending September 30, 2005
Twelve months ending December 31, 2005
Fifteen months ending March 31, 2006 Minimum Net Income
[***]
[***]
[***]
[***]
[***]
[***]"

               4.        Compliance Certificate.  Exhibit G to the Credit
Agreement is replaced in its entirety by Exhibit A to this Amendment.

               5.        No Other Changes.  Except as explicitly amended by this
Amendment, all of the terms and conditions of the Credit Agreement shall remain
in full force and effect and shall apply to any advance or letter of credit
thereunder.

               6.        Waiver of Default.  The Borrowers are in default of
Section 6.13 of the Credit Agreement as of December 31, 2004 (the “Existing
Default”). Upon the terms and subject to the conditions set forth in this
Amendment, the Lender hereby waives the Existing Default. This waiver shall be
effective only in this specific instance and for the specific purpose for which
it is given, and this waiver shall not entitle the Borrowers to any other or
further waiver in any similar or other circumstances.

               7.        Amendment Fee.  The Borrowers shall pay the Lender a
fully earned, non-refundable fee in the amount of $8,000 in consideration of the
Lender’s execution and delivery of this Amendment, which fee shall be due and
payable on April 1, 2005.

               8.        Conditions Precedent.  This Amendment, including the
waiver set forth in paragraph 6, shall be effective when the Lender shall have
received an executed original hereof.

               9.        Representations and Warranties.   The Borrowers hereby
represent and warrant to the Lender as follows:

        (a)        The Borrowers have all requisite power and authority to
execute this Amendment and to perform all of its obligations hereunder, and this
Amendment has been duly executed and delivered by the Borrowers and constitute
the legal, valid and binding obligation of the Borrowers, enforceable in
accordance with their terms.

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        (b)        The execution, delivery and performance by the Borrowers of
this Amendment have been duly authorized by all necessary corporate action and
do not (i) require any authorization, consent or approval by any governmental
department, commission, board, bureau, agency or instrumentality, domestic or
foreign, (ii) violate any provision of any law, rule or regulation or of any
order, writ, injunction or decree presently in effect, having applicability to
the Borrowers, or the articles of incorporation or by-laws of the Borrowers, or
(iii) result in a breach of or constitute a default under any indenture or loan
or credit agreement or any other agreement, lease or instrument to which any
Borrower is a party or by which it or its properties may be bound or affected.

        (c)        All of the representations and warranties contained in
Article V of the Credit Agreement are correct on and as of the date hereof as
though made on and as of such date, except to the extent that such
representations and warranties relate solely to an earlier date.

               10.        No Other Waiver.  Except as set forth in paragraph 6,
the execution of this Amendment and acceptance of any documents related hereto
shall not be deemed to be a waiver of any Default or Event of Default under the
Credit Agreement or breach, default or event of default under any Security
Document or other document held by the Lender, whether or not known to the
Lender and whether or not existing on the date of this Amendment.

               11.        Release.  The Borrowers hereby absolutely and
unconditionally release and forever discharge the Lender, and any and all
participants, parent corporations, subsidiary corporations, affiliated
corporations, insurers, indemnitors, successors and assigns thereof, together
with all of the present and former directors, officers, agents and employees of
any of the foregoing, from any and all claims, demands or causes of action of
any kind, nature or description, whether arising in law or equity or upon
contract or tort or under any state or federal law or otherwise, which any
Borrower has had, now has or has made claim to have against any such person for
or by reason of any act, omission, matter, cause or thing whatsoever arising
from the beginning of time to and including the date of this Amendment, whether
such claims, demands and causes of action are matured or unmatured or known or
unknown.

               12.        Costs and Expenses.  The Borrowers hereby reaffirm
their agreement under the Credit Agreement to pay or reimburse the Lender on
demand for all costs and expenses incurred by the Lender in connection with the
Loan Documents, including without limitation all reasonable fees and
disbursements of legal counsel. Without limiting the generality of the
foregoing, the Borrowers specifically agree to pay all fees and disbursements of
counsel to the Lender for the services performed by such counsel in connection
with the preparation of this Amendment and the documents and instruments
incidental hereto. The Borrowers hereby agree that the Lender may, at any time
or from time to time in its sole discretion and without further authorization by
the Borrowers, make a loan to the Borrowers under the Credit Agreement, or apply
the proceeds of any loan, for the purpose of paying any such fees,
disbursements, costs and expenses and the fee required under paragraph 7 hereof.

               13.        Miscellaneous.  This Amendment may be executed in any
number of counterparts, each of which when so executed and delivered shall be
deemed an original and all of which counterparts, taken together, shall
constitute one and the same instrument.

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

HESKA CORPORATION

By    /s/ JASON NAPOLITANO                           
              Jason Napolitano
     Its    Chief Financial Officer                           

WELLS FARGO BUSINESS CREDIT, INC.

By    /s/ TIM ULRICH                                          
          Tim Ulrich, Vice President   DIAMOND ANIMAL HEALTH, INC.

By    /s/ JASON NAPOLITANO                        
              Jason Napolitano
     Its     Chief Financial Officer                        

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[***]     – Certain information in this exhibit have been omitted and filed
separately with the Securities and Exchange Commission. Confidential treatment
has been requested with respect to the omitted portions.

Exhibit A to Eighth Amendment

COMPLIANCE CERTIFICATE

To:                                                                        
                  Wells Fargo Business Credit, Inc.

Date:                                                       , 20      

Subject:     Heska Corporation
                  Financial Statements

In accordance with our Second Amended and Restated Credit and Security Agreement
dated as of June 14, 2000 (the “Credit Agreement”), attached are the financial
statements of Heska Corporation (“Heska”) as of and for ________________, 20___
(the “Reporting Date”) and the year-to-date period then ended (the “Current
Financials”). All terms used in this certificate have the meanings given in the
Credit Agreement.

I certify that, to the best of my knowledge, the Current Financials have been
prepared in accordance with GAAP, subject to year-end audit adjustments, and
fairly present the Borrowers’ financial condition and the results of its
operations as of the date thereof.

                    Events of Default. (Check one):

  [   ]    The undersigned does not have knowledge of the occurrence of a
Default or Event of Default under the Credit
    Agreement.

  [   ]    The undersigned has knowledge of the occurrence of a Default or Event
of Default under the Credit Agreement
    and attached hereto is a statement of the facts with respect to thereto.

                    I hereby certify to the Lender as follows:

  [   ]    The Reporting Date does not mark the end of one of the Borrowers’
fiscal quarters, hence I am completing all
    paragraphs below except paragraph 4.

  [   ]    The Reporting Date marks the end of one of the Borrowers’ fiscal
quarters, hence I am completing all paragraphs
    below.

                    Financial Covenants. I further hereby certify as follows:

         1.        Accounts Payable.  Pursuant to Section 6.5 of the Credit
Agreement, as of the Reporting Date, the Borrowers [   ] are [   ] are not in
compliance with the requirement that they have no accounts payable more than 60
days past due.

         2.        Spread.  Pursuant to Section 2.7 of the Credit Agreement, as
of the Reporting Date, Heska’s Permanent Capital was, on a consolidated basis,

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[***]     – Certain information on this page have been omitted and filed
separately with the Securities and Exchange Commission. Confidential treatment
has been requested with respect to the omitted portions.

$_________________, which [   ] exceeds [   ] does not exceed the corresponding
Minimum Capital covenant (set forth in paragraph 3 below) by at least [***].

         3.        Minimum Capital.  Pursuant to Section 6.12 of the Credit
Agreement, as of the Reporting Date, Heska’s Capital was, on a consolidated
basis, $_________________, which [   ] satisfies [   ] does not satisfy the
requirement that such amount be not less than $_____________ on the Reporting
Date, as set forth in the table below:

  Date
December 31, 2004
January 31, 2005
February 28, 2005
March 31, 2005
April 30, 2005
May 31, 2005
June 30, 2005
July 31, 2005
August 31, 2005
September 30, 2005
October 31, 2005
November 30, 2005
December 31, 2005
January 31, 2006
February 28, 2006
March 31, 2006
April 30, 2006
May 31, 2006 Minimum Capital
[***]
[***]
[***]
[***]
[***]
[***]
[***]
[***]
[***]
[***]
[***]
[***]
[***]
[***]
[***]
[***]
[***]
[***]

  The covenant amounts set forth above for dates after December 31, 2004, shall
be adjusted upward or downward, respectively, on a dollar-for-dollar basis by
the amount by which Heska’s Capital, on a consolidated basis as of December 31,
2004, as reflected in Heska’s audited financial statements, exceeds or is less
than [***].

         4.        Minimum Net Income.  Pursuant to Section 6.13 of the Credit
Agreement, as of the Reporting Date, Heska’s Net Income was, on a consolidated
basis, $_________________, which [   ] satisfies [   ] does not satisfy the
requirement that such amount be no less than $______________ on the Reporting
Date, as set forth in the table below:

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[***]     – Certain information on this page have been omitted and filed
separately with the Securities and Exchange Commission. Confidential treatment
has been requested with respect to the omitted portions.

  Period
Twelve months ended December 31, 2004
Three months ending March 31, 2005
Six months ending June 30, 2005
Nine months ending September 30, 2005
Twelve months ending December 31, 2005
Fifteen months ending March 31, 2006 Minimum Net Income
[***]
[***]
[***]
[***]
[***]
[***]

         5.        Minimum Liquidity.  Pursuant to Section 6.14 of the Credit
Agreement, as of the Reporting Date, Heska’s Liquidity was, on a consolidated
basis, $_________________, which [   ] satisfies [   ] does not satisfy the
requirement that such amount be no less than $1,500,000 on the Reporting Date.

         6.        Minimum Individual Book Net Worth.  Pursuant to Section 6.15
of the Credit Agreement, as of the Reporting Date, Heska’s Book Net Worth was
$_________________ and Diamond’s Book Net Worth was $_________________, which
[   ] satisfies [   ] does not satisfy the requirement that such amounts be no
less than zero on the Reporting Date.

         7.        Capital Expenditures.  Pursuant to Section 7.10 of the Credit
Agreement, as of the Reporting Date, Heska’s Capital Expenditures were, in the
aggregate and on a consolidated basis, $_______________ which [   ] satisfies
[   ] does not satisfy the requirement that such amount be not more than
$_______________ during the period ending on the Reporting Date, as set forth in
the table below:

  Period
Twelve months ended December 31, 2004
Three months ending March 31, 2005
Twelve months ending December 31, 2005
Four months ending April 30, 2006
Five months ending May 31, 2006 Maximum Capital Expenditures
[***]
[***]
[***]
[***]
[***]

Attached hereto are all relevant facts in reasonable detail to evidence, and the
computations of the financial covenants referred to above. These computations
were made in accordance with GAAP.

    HESKA CORPORATION

By                                                     
       Its