Alkaline phosphatase, leucine aminopeptidase, and alanine aminotransferase activities with obstructive and toxic hepatic disease in cats.

The activities of serum alkaline phosphatase (serum ALP), leucine aminopeptidase (serum LAP), and alanine aminotransferase (serum ALT) were determined in 15 cats before and after treatment by 3 methods: common bile duct occlusion, left hepatic duct(s) occlusion, and carbon tetrachloride administration. Significant increases in serum ALP, LAP, and ALT activities occurred in all cats in the 3 groups. Sustained mean increases of ninefold in ALP and 13-fold in LAP occurred in the cats with common bile duct occlusion. Lesser mean increases of these enzymes (fourfold) occurred in the cats with partial biliary occlusion. Transient mean increases (100-fold) in ALT occurred in the carbon tetrachloride-treated cats. Urine ALP excretion was measured in 3 cats with common bile duct occlusion. There was no significant difference between rates of urine ALP excretion before and after common bile duct occlusion. Specific ALP activities of hepatic extracts from normal cats and biliary-obstructed cats were compared. Mean specific activity was onefold higher in liver from cats with common bile duct occlusion of 21 days' duration. The findings in the present studies were interpreted to indicate that serum ALP and LAP are useful to detect biliary occlusive disease in cats and, in conjunction with serum ALT, may be used to differentiate primary hepatodegenerative disease and biliary occlusive disease.