Liver function tests in dogs with congenital portosystemic shunts and their potential to determine persistent shunting after surgical attenuation.

Portosystemic shunts (PSS) are congenital or acquired vascular anomalies that cause blood to bypass the liver. Liver function tests, such as fasting ammonia, ammonia tolerance test, and (paired) serum bile acids, are reliable for the diagnosis of PSS in dogs. Surgical attenuation is a common treatment for congenital PSS. Following surgical attenuation, it is useful to evaluate shunt closure. In this critical review, the ability of liver function tests to determine the presence and degree of residual shunting following surgical attenuation of canine PSS is discussed. Despite the availability of several liver function tests, a single rapid, simple, cost-effective, sensitive and specific test to evaluate surgical attenuation of PSS is not available.