X0303 4 2011-06-01 0 0001323974 MWI Veterinary Supply, Inc. MWIV 0001334076 Hay James S 3041 W. PASADENA DR. BOISE ID 83705 0 1 0 0 Chief Information Officer Common Stock, par value $0.01 per share 2011-06-01 4 M 0 1500 .1818 A 4206 D Common Stock, par value $0.01 per share 2011-06-01 4 S 0 1340 82.8299 D 2866 D Common Stock, par value $0.01 per share 2011-06-01 4 S 0 160 84.30 D 2706 D Employee Stock Option (right to buy) .1818 2011-06-01 4 M 0 1500 0 D 2008-09-30 2012-06-18 Common Stock, par value $0.01 per share 1500 0 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 18, 2010. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $82.5149 to $83.00, inclusive. Mr. Hay has provided to MWI Veterinary Supply, Inc. (the "Company") and undertakes to provide to any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. Ryan Cleverley as attorney-in-fact for James S. Hay 2011-06-03