Dogs are most commonly at risk in the first year of life, but unvaccinated dogs of all ages are susceptible. ICH is transmitted by direct contact/ingestion of urine, feces, or saliva of infected dogs. Recovered dogs are still infectious as they shed virus in their urine for 6 - 9 months, and young puppies are particularly susceptible. The virus is relatively hardy and can survive for months in the environment under ideal conditions.

Clinical signs develop after an incubation period of 4-7 days and most commonly include lack of appetite, fever, pale gums, conjunctivitis, coughing, abdominal pain, vomiting and diarrhoea. Sometimes, the dog may later develop jaundice. In some dogs that recover, a clouding of the cornea occurs, known as 'blue eye' which usually resolves itself over time. Occasionally the disease is so severe as to cause sudden death before any signs have developed.

Treatment - There is no specific treatment for infectious canine hepatitis. Intravenous fluids and supportive care are sometimes necessary. Fortunately, excellent vaccines are available to immunize puppies as well as adults. The vaccines may contain adenovirus type 1 or type 2. Adenovirus type 2 (CAV-2) is a cause of cough in the canine. Because the viruses are similar, vaccines against one cross protect against the other. Modern vaccines contain either CAV-1 or CAV-2, but not both. However, either one protects against both hepatitis and cough.

Blood transfusions may be necessary in severely ill dogs. A broad-spectrum antibiotic should be given. Because tetracyclines may cause discoloration of the teeth during tooth development, they should not be used in puppies before their permanent teeth erupt. Although the transient corneal opacity (that may be seen during the course of ICH or be associated with vaccination with attenuated CAV-1 vaccines) usually requires no treatment, atropine ophthalmic ointment may alleviate the painful ciliary spasm that is sometimes associated with it. Dogs with corneal clouding should be protected against bright light. Systemic corticosteroids are generally contraindicated for treatment of corneal opacity associated with ICH.

Prevention - Vaccination against ICH is recommended at the time of canine distemper vaccinations. Maternal antibody from immune bitches interferes with active immunization in puppies until they are 9-12 wk old.

On recovery, dogs eat well but regain weight slowly. Bilateral corneal opacity develops 7-10 days after the acute signs disappear in 25% of recovered dogs and usually disappears spontaneously. In mild cases, transient corneal opacity may be the only sign of disease.