Infectious
canine hepatitis (ICH) is caused by what is called a canine adenovirus
type 1 (CAV-1) and has no connection with hepatitis in humans.
Dogs and foxes can both be infected by inhaling or swallowing material
contaminated with faeces, saliva or urine from infected animals.
They can harbor the virus which is passed in the urine for 6-9 months
after infection. The virus is stable in the environment for some time
and attacks primarily the liver, kidneys, eyes and the inner lining of
blood vessels of dogs that become infected. The canine infectious
hepatitis virus persists for months in the urine of most dogs that
recover from the infection, serving as a constant source of infection
to susceptible dogs. Puppies in their first year of life are at most
risk but all dogs are susceptable. It is the puppies between two and
six weeks of age that have the highest mortality rate.
Some dogs may
become ill so quickly that owners think the pet has been poisoned.
Clinical signs include a very sudden and rapid onset of fever,
abdominal pain, small hemorrhages on the lips, seizures, convulsions
and death. Dogs can be dead a few hours after clinical signs start.
Less than fatal cases will exhibit depression, loss of appetite, some
vomiting and diarrhea, a high fever and enlargement of the lymph nodes
pale conjuctivae and gums, and yellowing of the whites of the eyes
(jaundice)may occur.
Still other dogs
may develop blue eye where one or both corneas become a cloudy blue
colour. In most cases this clouding will disappear within a
few days without additional treatment but, if it persists, veterinary
advice should be sought. A similar clouding of the eye may be
seen in some puppies after vaccination against infectious canine
hepatitis when a live CAV-1 vaccine has been used. Most modern
vaccines contain live CAV-2 antigens and do not cause blue eye.
Some dogs will have very mild fever and throat inflammation, while
others will develop a more severe chronic hepatitis that leads to a
slowly progressive deterioration of the patient. It is important to
note that this illness cannot affect people and that human hepatitis
involves a virus specific to people. Diagnosis can be a challenge,
based on history, including vaccine history, clinical signs, blood
counts, serum chemistries and special serologic tests specific for
ICH. Prevention by vaccination is best so have your puppy
vaccinated early. All dogs should be vaccinated every three or
four weeks from six or eight to sixteen weeks of age, then yearly after
that.
Treatment There is no
specific treatment for the ICH virus so supportive care is essential to
save the dog. Heavy fluid therapy through the IV route, antibiotics to
protect against secondary infection and strong nutritional support are
essential. The prognosis is good for milder cases, poor for the more
severely affected dogs.
