Canine hepatitis has long been confused with canine distemper. The disease was first recognized in the 1920s in silver foxes in which signs of inflammation of the brain (encephalitis) were most prominent. It was known as early as 1927 that the same virus was highly contagious to dogs. However, in dogs, the disease causes inflammation of the liver.
The disease is caused by an adenovirus which are more resistant to common detergents and disinfectants. However, the virus is susceptible to iodine, sodium hydroxide, and chlorine bleach.
The disease can be found in dogs, coyotes, timber wolves, skunks, and bears.
Following inhalation or digestion of the virus, it localizes in the tonsils before disseminating to the lymph nodes and eventually the bloodstream. Once in the blood, the virus targets the liver, kidneys, eyes, and the cells lining the inner surface of the blood vessels. Once an antibody response arises (usually within 5 to 7 days of infection), the virus is rapidly cleared from most areas of the body but may persist in the kidneys where it is excreted into the urine.
Dogs surviving severe clinical illness may develop a transient clouding of the cornea, known colloquially as blue eye. This usually dissipates within a few weeks.
Several clinical forms hepatitis are recognized.
This is characterized by a fever lasting 24 to 48 hours followed occasionally by a second fever spike within a few days. Some clinical signs include:
This is also known as extremely rapid onset and is typical of very young puppies, with death occurring within a day or less. Clinical signs include:
This is the classic form of hepatitis. Although it typically occurs in puppies between the ages of 6 and 10 weeks, it can affect adolescent and mature dogs. Clinical signs include:
In fortunate cases, recovery occurs within 4 to 7 days. In less fortunate cases, more serious clinical signs appear, including:
Treatment is aimed at providing secondary support for the dog by minimizing the effects of shock, hemorrhages, neurological disease, and prevention of secondary infection.
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