Acquisitions (Details)	12 Months Ended
	Dec. 31, 2011 Hospitals Laboratories	Dec. 31, 2010 Hospitals Laboratories	Dec. 31, 2009 Laboratories Hospitals
Summary of acquisitions of animal hospitals and laboratories
Total animal hospitals	13	39	18
Total laboratories	3	3	3
Animal Hospital [Member] | Acquisitions, excluding BrightHeart and Pet DRx [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Businesses Acquired	18	27	27
Animal Hospital [Member] | BrightHeart [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Businesses Acquired	9
Animal Hospital [Member] | Pet DRx [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Businesses Acquired		23
Animal Hospital [Member] | Acquisitions relocated into our existing animal hospitals [Member]
Summary of acquisitions of animal hospitals and laboratories
Acquisitions relocated into our existing animal hospitals	(3)	(2)	(5)
Animal Hospital [Member] | Sold, closed or merged [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Properties Sold Closed or Merged	(11)	(9)	(4)
Laboratories [Member] | Acquisitions [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Businesses Acquired	1		2
Laboratories [Member] | Acquisitions relocated into our existing laboratories [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Acquired Laboratories Relocated To Existing Laboratories			(2)
Laboratories [Member] | New facilities [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Laboratories Created	2	4	3
Laboratories [Member] | Closed or merged [Member]
Summary of acquisitions of animal hospitals and laboratories
Number of Properties Sold Closed or Merged		(1)