Acquisitions (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of acquisitions of animal hospitals and laboratories
Number of Properties Sold Closed or Merged		(6)	(11)	(9)
Acquisitions relocated into our existing animal hospitals		(6)	(3)	(2)
Total animal hospitals	13	68		39
Total laboratories		2	3	3
AVC [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Businesses Acquired		44	0	0
Acquisitions, excluding BrightHeart and Pet DRx [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Businesses Acquired		35	18	27
BrightHeart [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Businesses Acquired		0	9	0
Pet DRx [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Businesses Acquired		0	0	23
Acquisitions [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Businesses Acquired	1	1		0
Acquisitions relocated into our existing laboratories [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Acquired Laboratories Relocated To Existing Laboratories		(1)	0	0
New facilities [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Laboratories Created		2	2	4
Closed or merged [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Properties Sold Closed or Merged		0	0	(1)