Exhibit
4.3


MWI
VETERINARY SUPPLY, INC


CERTIFICATE
OF AMENDMENT


OF


AMENDED
AND RESTATED CERTIFICATE OF INCORPORATION


MWI Veterinary
Supply, Inc. (the “Corporation”), a corporation organized and existing under
and by virtue of the General Corporation Law of the State of Delaware,


DOES
HEREBY CERTIFY:


FIRST:   That
the Board of Directors of said Corporation, by unanimous written consent filed
with the minutes of the Board, adopted resolutions proposing and declaring
advisable the following amendment to the Amended and Restated Certificate of
Incorporation of said Corporation:


RESOLVED, that the Board of Directors of the Corporation
deems it advisable and in the Corporation’s best interest and approves an
increase in the amount of the Corporation’s authorized capital stock, and in
order to effect such change, the Corporation’s Amended and Restated Certificate
of Incorporation  be, and hereby is,
amended in accordance with Section 242 of the General Corporate Law of the
State of Delaware as follows:


(a)  The first paragraph of
Section A of Article IV, is hereby deleted in its entirety.


(b)  The following paragraph is
hereby inserted in replacement thereof:


“The total number of shares of capital stock which the Corporation
shall have the authority to issue is 41,000,000 shares, divided into two
classes consisting of 1,000,000 shares of preferred stock, par value $0.01 per
share (the “Preferred Stock”) and 40,000,000 shares of common stock, par value
$0.01 per share (the “Common Stock”).”


and further


RESOLVED, that the foregoing amendment of the Corporation’s
Amended and Restated Certificate of Incorporation be submitted for
consideration by the stockholders of the Corporation and the next annual
meeting of stockholders; and further













RESOLVED, that, upon approval by the stockholders of
the Corporation of the foregoing amendment of the Corporation’s Amended and
Restated Certificate of Incorporation, the proper officers of the Corporation
be, and each of them hereby is, authorized, empowered and directed to execute
and file with the Office of the Secretary of State of the State of Delaware a
Certificate of Amendment of the Corporation’s Amended and Restated Certificate
of Incorporation, attached as Exhibit A hereto, effecting the foregoing
proposed amendment; and further


RESOLVED, that the proper
officers of the Corporation be, and each of them hereby is, in the name and on
behalf of the Corporation, and under its corporate seal or otherwise,
authorized, empowered and directed to take or cause to be taken, all such
further actions in connection with the transactions contemplated by the
foregoing resolutions, and to execute and deliver, or cause to be executed and
delivered, such documents as they shall deem necessary or advisable to
effectuate the intent and purposes of the foregoing resolutions and the actions
contemplated thereby.


SECOND:   That,
the stockholders of the Corporation have approved the foregoing amendment at an
annual meeting of the stockholders called and held upon notice in accordance
with Section 222 of the General Corporation Law of the State of Delaware, and
that the stockholders have duly adopted the amendment in accordance with the applicable
provisions of Section 242 of the General Corporation Law of the State of
Delaware.


[signature
page follows]













IN
WITNESS WHEREOF, MWI Veterinary Supply, Inc. has caused this
Certificate of Amendment to be signed by James F. Cleary, its President and
Chief Executive Officer, this 7th day of February, 2007.


	
  

  	
   

  	
  MWI VETERINARY SUPPLY, INC.

  
	
   

  	
   

  	
  By:

  	
   

  	
  /s/ James F. Cleary

  
	
   

  	
   

  	
   

  	
   

  	
  James F. Cleary

  
	
   

  	
   

  	
   

  	
   

  	
  President and
  Chief Executive Officer