Chronic active hepatitis (CAH) is a chronic and progressive inflammation of the liver of dogs that leads eventually to the replacement of normal liver tissue with scar tissue. The disease is also called canine chronic inflammatory hepatic disease. Affected individuals may be ill for weeks to months with signs of intermittent anorexia, weight loss, lethargy, excessive urinating and drinking, and jaundice. In the end stages of this disease when scarring of the liver is severe and the liver can no longer function properly, affected dogs may develop fluid accumulation in the abdomen and signs of hepatic encephalopathy. Hepatic encephalopathy is malfunction of the brain due to the accumulation of toxins that are ordinarily cleared from the blood stream by the liver.

There are several diseases/disorders that can appear similar to CAH. These include:

Cancer in the liver, such as lymphosarcoma

Hepatotoxins, which are chemicals or drugs that injure the liver and include certain drugs, heavy metals, certain chemical flea and tick dips and sprays

Chronic hepatitis due to bacterial, fungal, protozoal or parasitic infections

Chronic liver disease due to abnormal copper storage and accumulation in the liver

Pancreatitis, an inflammation of the pancreas that often causes vomiting, lethargy, and inappetence

Pancreatic cancer that blocks the biliary tract (bile duct system) causing similar symptoms.

Intestinal inflammation, tumors or foreign bodies

Other causes of jaundice

Primary gallbladder diseases, such as stones, cancer, inflammation, or infection

Other causes of abnormal clotting of the blood (bleeding disorders)