Symposium on liver function

Hepatobiliary disease is a common cause of morbidity and mortality in small-animal practice. Several factors, however, complicate the clinical detection of liver disease.

The liver plays a central role in a diverse array of processes, including carbohydrate, lipid, and protein metabolism; detoxification of metabolites; storage of vitamins, trace metals, fat, and glycogen; fat digestion; and immunologic surveillance. Clinical signs of hepatobiliary disease reflect changes in these varied functions, so these signs often overlap with those of diseases involving other organ systems.

Additionally, the liver's dual blood supply and high blood flow make it uniquely sensitive to injury from systemic disease processes and diseases in organ systems directly drained by the portal circulation. In many cases, differentiating between primary and secondary hepatobiliary disease is difficult.

Furthermore, specific signs of hepatobiliary disease typically occur in advanced stages of disease because of the liver's large reserve and regenerative capacity. Late in the disease progression, therapeutic options are limited and the short-term prognosis is poor. So early and accurate identification of cases of hepatobiliary disease is important to improve long-term outcome.

This symposium's goal is to provide practitioners with a diagnostic approach to patients with hepatobiliary disease. The first article provides guidelines on how to approach asymptomatic dogs with elevated liver enzyme activities. In the article, Dr. Cynthia Webster and I discuss the diagnostic utility of serum enzyme measurement, bile acid measurement, imaging, and hepatic biopsy in diagnosing hepatobiliary disease. We also review common extrahepatic causes of increased hepatobiliary enzymes and address the issue of corticosteroid and phenobarbital enzyme induction vs. toxic damage from these drugs.

The second article deals with diagnosing and treating feline inflammatory hepatobiliary disease. We discuss the disease's proposed causes, diagnosis, definitive and supportive treatment, secondary complications, and long-term monitoring.

In the final article, Diana Burger, Amie Carrier, and Dr. Karen Tobias describe how to perform a surgical hepatic biopsy. By using the proper technique, general practitioners can obtain representative hepatic tissue samples, which will aid in a definitive diagnosis.

—Dr. Johanna Cooper