Lines of Business (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Lines of Business
External revenue	$ 376,105	$ 353,919	$ 731,228	$ 684,653
Total revenue	376,105	353,919	731,228	684,653
Direct costs	279,273	260,435	554,618	508,374
Gross profit	96,832	93,484	176,610	176,279
Selling, general and administrative expense	26,663	41,045	52,846	67,185
Net loss (gain) on sale of assets	60	(14)	149	11
Operating income (loss)	70,109	52,453	123,615	109,083
Depreciation and amortization	13,076	10,999	26,456	21,706
Capital expenditures	16,400	11,876	28,434	27,925
Total assets	1,843,412		1,843,412		1,766,422
Animal Hospital [Member]
Lines of Business
External revenue	291,332	267,595	561,273	514,263
Total revenue	291,332	267,595	561,273	514,263
Direct costs	238,392	218,567	468,780	423,558
Gross profit	52,940	49,028	92,493	90,705
Selling, general and administrative expense	6,044	5,673	12,127	11,260
Net loss (gain) on sale of assets	51	(35)	129	(51)
Operating income (loss)	46,845	43,390	80,237	79,496
Depreciation and amortization	9,533	7,630	19,406	14,982
Capital expenditures	13,236	9,849	22,771	22,977
Total assets	1,338,034		1,338,034		1,320,619
Laboratory [Member]
Lines of Business
External revenue	72,955	73,259	142,051	142,659
Intercompany revenue	11,430	9,713	21,883	18,493
Total revenue	84,385	82,972	163,934	161,152
Direct costs	43,716	42,416	86,535	84,068
Gross profit	40,669	40,556	77,399	77,084
Selling, general and administrative expense	6,853	6,527	13,489	12,681
Net loss (gain) on sale of assets	7		18	1
Operating income (loss)	33,809	34,029	63,892	64,402
Depreciation and amortization	2,508	2,396	4,979	4,809
Capital expenditures	1,728	1,506	2,964	2,338
Total assets	228,571		228,571		215,483
Medical Technology [Member]
Lines of Business
External revenue	11,818	13,065	27,904	27,731
Intercompany revenue	4,391	1,537	7,401	2,668
Total revenue	16,209	14,602	35,305	30,399
Direct costs	11,419	10,255	26,057	21,221
Gross profit	4,790	4,347	9,248	9,178
Selling, general and administrative expense	3,584	3,404	7,140	6,919
Net loss (gain) on sale of assets	2	14	2	54
Operating income (loss)	1,204	929	2,106	2,205
Depreciation and amortization	668	605	1,325	1,206
Capital expenditures	258	124	1,017	206
Total assets	64,851		64,851		69,082
Corporate [Member]
Lines of Business
Selling, general and administrative expense	10,182	25,441	20,090	36,325
Net loss (gain) on sale of assets		7		7
Operating income (loss)	(10,182)	(25,448)	(20,090)	(36,332)
Depreciation and amortization	685	618	1,365	1,199
Capital expenditures	1,627	858	2,585	3,185
Total assets	229,608		229,608		175,297
Intercompany Eliminations [Member]
Lines of Business
Intercompany revenue	(15,821)	(11,250)	(29,284)	(21,161)
Total revenue	(15,821)	(11,250)	(29,284)	(21,161)
Direct costs	(14,254)	(10,803)	(26,754)	(20,473)
Gross profit	(1,567)	(447)	(2,530)	(688)
Operating income (loss)	(1,567)	(447)	(2,530)	(688)
Depreciation and amortization	(318)	(250)	(619)	(490)
Capital expenditures	(449)	(461)	(903)	(781)
Total assets	$ (17,652)		$ (17,652)		$ (14,059)