This disease, now rare in London, is caused by an adenovirus called CAV-1. Its close relative CAV-2 is one of the viral causes of kennel cough. Viral hepatitis occurs most frequently in unvaccinated dogs under a year of age. Many, if not most dogs experience a subclinical infection with only a one day fever. Young pups under six weeks old may suffer acute abdominal pain and die of shock within a day. Death is so rapid owners sometimes think their pups have been poisoned. Older individuals have a high fever, abdominal pain, and produce bloody vomit and diarrhea . Some are light sensitive.
Diagnosis depends upon a history of no vaccination and clinical signs. Occasionally serology or biopsy is carried out to confirm the diagnosis. Dogs that recover often develop a clouding to the cornea causing so-called "blue eye".
Effective treatment depends upon quick and efficient pain and shock control. Fluid replacement is vital. Antibiotics may be used to prevent secondary infection.
The first vaccines in the 1960s, based on CAV-1 provided protection but occasionally caused "blue eye". Today all modified-live hepatitis vaccines are produced from CAV-2 which cross protects.