A variety of disease states, vascular anomalies and metabolic disorders result in liver dysfunction. This newsletter reviews the more common causes of liver disease and discusses the associated hemostatic abnormalities.

The most common hepatic vascular anomaly, portosystemic shunts are functional vascular channels from the portal to systemic circulation that bypass liver sinusoids. When these are of significant extent, they lead to hepatic encephalopathy and liver failure. The disorder is congenital in dogs and cats but is much more frequently seen in dogs. Most cases are diagnosed in animals less than 3 years old. Shunts are likely to be single and extrahepatic in breeds such as the Yorkshire and Cairn Terriers, Dachshund, and Miniature Poodle. In the Yorkshire Terrier they may be found incidentally, even in geriatric pets during routine laboratory screening as part of a wellness examination.

Breeders also screen affected families or breeds with bile acids testing, which may reveal the presence of asymptomatic shunts. Intrahepatic shunts are most often reported in the Doberman Pinscher, Golden and Labrador Retrievers, Irish Wolfhound and Samoyed. Diagnosis is usually based on finding high levels of fasting and post-prandial bile acids, increased blood ammonia levels, and variable changes in laboratory parameters such as increased ALT and SAP, decreased BUN, and mild anemia, hypoalbuminemia and hypoglycemia. Confirmatory tests include ultrasonography, portography or scinography. Some single or large multiple shunts can be corrected surgically, while others can only be managed medically. Prognosis varies but is generally guarded to poor.

Copper toxicosis is a metabolic disorder in which hepatic accumulation of dietary copper produces progressive hepatopathy with cirrhosis and liver failure. Breeds most often affected include the Bedlington, West Highland, Kerry Blue and Skye Terriers, Doberman Pinscher, Cocker Spaniel, Labrador Retriever, German Shepherd Dog, Miniature Schnauzer, Bulldog and Pekingese. The disease in Bedlington Terriers has autosomal inheritance and is a model for human Wilson's disease. The specific gene involved is linked to esterase D which is used as a marker enzyme for genetic screening. Clinically, the diagnosis is made by the presence of a bronzing skin color in an affected breed, increased ALT and SAP with reduced serum protein, and a small liver. Confirmation involves genetic marker testing in Bedlingtons and/or hepatic biopsy. Long-term prognosis is guarded to poor.

A severe accumulation of fat in the liver, termed hepatic lipidosis, occurs in cats and dogs and is idiopathic in the cat. Typically, affected cats are obese and anorexic, and the condition is often associated with a recent stress event. It may be secondary to diabetes mellitus, malnutrition or exposure to drugs or toxins. The Miniature Schnauzer is one of the more commonly affected dog breeds. Diagnosis is based on finding very high SAP (up to 20 times elevated) and ALT (up to 10 times elevated), and high bilirubin and fasting bile acids. Ultrasonography and hepatic biopsy are used for confirmation. Prognosis is guarded to poor.

Chronic active hepatitis is a progressive inflammatory condition believed to have an autoimmune or infectious cause. It has been associated with infectious canine hepatitis, leptospirosis and copper toxicosis, and has a genetic predisposition in breeds such as the Shetland Sheepdog, Golden Retriever and Doberman Pinscher. The condition progresses to liver failure. It has not been reported in cats.