EXHIBIT 10.18

**CERTAIN INFORMATION IN THIS EXHIBIT HAS BEEN OMITTED AND FILED SEPARATELY WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO THE
OMITTED PORTIONS.

COMPANION ANIMAL AAHA MARKETLINK MANAGEMENT AGREEMENT

This Agreement dated and effective as of September 1, 2009 is made by and between PFIZER Inc.,235 East 42nd Street,
New York, New York 10017 (hereinafter, "PFIZER") and MWI Veterinary Supply Co.,651 S. Stratford Drive, Ste 100, Meridian, ID 83642 ("MWI").

1.     PFIZER
hereby agrees to supply MWI as a designated product supplier for the PFIZER companion animal Products set forth on Exhibit A (the "Products"), to purchase
from PFIZER and to resell to certain selected Veterinary Hospitals serviced by MWI who are members of the AAHA/MarketLink arrangement and listed in Exhibit E hereto, subject to the following
terms and conditions.

2.     MWI
recognizes and agrees to the following:



3.     MWI
agrees to:



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4.     PFIZER
shall:



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5.     Nothing
in this Agreement shall be deemed to limit PFIZER's ability to sell Products to any other party.

6.     All
purchases by MWI pursuant to this Agreement shall be in accordance with the terms of PFIZER's Pricing and Shipping Policies, as may be amended by PFIZER from time to
time.

7.     The
following standard conditions shall apply to all Sales under this Agreement:



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8.     This
Agreement shall not be binding upon PFIZER until it is approved by PFIZER at its New York, New York headquarters.

9.     This
Agreement shall be effective as of the date first written above and shall continue in force (hereinafter, the "Contract Term") until December 31, 2009. Either
party may terminate this agreement prior to the expiration date of the Contract Term (i) with or without cause, upon thirty (30) days written notice to the other party, or
(ii) immediately upon written notice, in the event of a material breach by the other party. Notwithstanding the above, PFIZER may terminate this Agreement at any time on 15 days .
written notice to MWI in the event that PFIZER determines, in its sole discretion, that MWI has failed to comply with one or more of the terms and conditions set forth in paragraph 3 above. In
addition, at its election, PFIZER may terminate this Agreement, upon thirty (30) days written notice to MWI, in the event that MWI fails to meet the level of Sales identified in Chart B
of Exhibit D for two consecutive months.

10.   MWI
and PFIZER acknowledge that in the performance of their duties hereunder MWI and PFIZER may obtain access to "Confidential Information" (as defined below) of each
other. MWI and PFIZER agree that during the term of this Agreement and for a period of three (3) years after the termination of this Agreement, unless specifically permitted in writing by the
other party, to (a) retain in confidence and not disclose to any third party and (b) use only for the purpose of carrying out their duties hereunder, any such Confidential Information.
As used herein the term "Confidential Information" means any information, or data, whether of a business or scientific nature and whether in written, oral or tangible form, relating to PFIZER's and
MWI's business or potential business or its research and development activities, not generally available to or known to the public, and not otherwise known to the receiving party, that is disclosed to
or learned by the other party pursuant hereto. Upon completion of the work provided for hereunder or other termination of this Agreement each party will return to the other party any documents, or
copies thereof, or any product samples, containing or constituting Confidential Information disclosed to or generated by either party in connection with this Agreement.

11.   This
Agreement shall be governed by the laws of the State of New York applicable to contracts to be fully performed therein. This Agreement is not assignable without the
express written consent of PFIZER, and may be modified or amended only in writing signed by the party to be bound.

12.   This
Agreement and documents referred to herein embody the entire understanding between the parties hereto, will supersede prior agreements relating to the Products, and
may be modified only in writing and signed by the parties to be bound. No activities conducted pursuant to this Agreement or related thereto, including but not limited to the future planning
activities of the parties, shall be deemed to give rise to any obligations on the part of either party other than as expressly provided for herein.

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IN
WITNESS WHEREOF, intending to be legally bound, the parties have executed this Agreement.

MWI VETERINARY SUPPLY CO.

PFIZER INC.BY:

/s/ JIM CLEARY

BY:

/s/ CLINTON A. LEWISPrint Name:

Jim Cleary



Clinton A. LewisTitle:

President



President U.S. Operations, PFIZER Animal HealthDate:

9/28/09

Date:

10/17/09


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