Introduction
Chronic hepatitis is one of the most common chronic hepatic conditions in dogs and cats and is characterized by ongoing inflammation with hepatocellular necrosis, regeneration, and fibrosis.
Evidence of fibrosis usually indicates severe disease. Advanced fibrosis will progress to cirrhosis, which in turn leads to portal hypertension, ascites, and acquired portosystemic shunts. In cats the inflammation is more directed at the bile ducts causing cholangitis or cholangio-hepatitis.Although there are many known causes of chronic hepatitis, in most cases the cause is never identified. Causes include drugs (anticonvulsants, non-steroidal anti-inflammatories, antibiotics acetaminophen, methimazole/carbimazole, anthelmintics, amiodarone), infectious diseases (leptospirosis, herpes virus, canine adenovirus-1, Ehrlichia, Bartonella), and toxins (xylitol, copper, aflatoxins, cycads).
Certain breeds are more prone to develop chronic hepatitis: West Highland White Terriers, Labrador Retrievers, Scottish Terriers, Skye Terriers, American and English Cocker Spaniels, Doberman Pinchers, Dalmatians, Bedlington Terriers, and Standard Poodles.