Alterations of prothrombin time and activated partial thromboplastin time in dogs with hepatic disease.

Reference intervals for prothrombin time (PT) and activated partial thromboplastin time (APPT) of undiluted and serial dilutions of citrated platelet-poor plasma were determined for 30 healthy dogs. The PT and APTT were similarly determined for 32 dogs with naturally occurring hepatic disease. Hepatic disease was confirmed by histopathologic examination of hepatic biopsy materials and comprised degeneration (13 dogs), inflammation (11 dogs), cirrhosis (4 dogs), and neoplasia (4 dogs). Coagulation test values were compared with serum alanine aminotransferase, alkaline phosphatase, and gamma-glutamyl transpeptidase activities and Bromsulphalein retention for sensitivity in detecting hepatic disease in the dog. Coagulation test results were at variance with reference values in 66% of the 32 dogs with hepatic disease; serum alanine aminotransferase, alkaline phosphatase, and gamma-glutamyl transpeptidase were increased in 59%, 72%, and 75%, respectively and Bromsulphalein retention was increased in 22% of the 32 dogs. Thus, the PT and APTT were sensitive indicators of hepatic disease. However, the PT and APTT lacked specificity for any given hepatic disease. The sensitivity of the coagulation tests for detecting hepatic disease was enhanced by using dilutions of citrated platelet-poor plasma. Only 15% of dogs with hepatic disease showed variances from reference values in the coagulation tests done with undiluted plasma, but 66% showed variances in the tests with dilutions of plasma. Coagulation tests were also done in 13 dogs with normal hepatic function amd morphology, but with various extrahepatic diseases: chronic renal disease (5 dogs), dirofilariasis (4 dogs), encephalitis (1 dog), cutaneous disease (2 dogs), and femoral fracture (1 dog). Twelve of the 13 dogs had coagulation test values within the reference intervals.