such tests include hepatic function tests measuring serum bilirubin blood ammonia and total serum bile acid concentrations hepatobiliary histologic examination or interpreting hepatobiliary enzyme activities in concert increases in serum alt activity are considered liver specific in dogs alt activity can increase with severe muscle necrosis but simultaneous evaluation of serum creatine kinase activity can rule out a muscle source 3 4 alt is a cytosolic enzyme and leakage occurs with damage to hepatobiliary membranes