Causes of Infectious Canine Hepatitis
Canine infectious hepatitis (ICH) is caused by a specific virus known as canine adenovirus type 1 (CAV-1). There is also a canine adenovirus type 2, which causes respiratory disease. The CAV-1 virus is transmitted between dogs by direct oral or nasal contact with the body secretions from an infected dog, such as urine, feces, saliva and nasal discharge. Exposure to urine seems to be the most common route of infection in dogs. Some external parasites can carry CAV-1. The virus also can be transmitted on fomites, which are inanimate objects or items such as bedding, feces, leashes and shoes, although this mode of transmission is much less common that direct oronasal contact. CAV-1 first lands in the dog’s tonsils and lymph nodes, where it begins to propagate. From there, viral particles disseminate throughout the body, traveling in the blood. The virus lodges and multiplies in various tissues, with a particular fondness for the liver, kidneys and lining of blood vessels. Viral particles are excreted in all bodily secretions starting about 5 days after the dog becomes infected. Even if the dog recovers from this illness, it will continue to shed the virus - and to be infective to other dogs - for up to 9 months.
Preventing Infectious Hepatitis
Infectious canine hepatitis can almost always be prevented by vaccination against the canine adenovirus. The modified live vaccine is part of some fairly common combination vaccines referred to in the veterinary profession as “DHLPP” and “DH2PP”. The “H” part of these vaccines is the component that provides protection against adenovirus. It is important to remember that vaccines do not provide absolute protection in all cases. In other words, no vaccine is 100% effective all of the time. However, vaccination is usually extremely effective against this particular canine virus. Most veterinarians recommend an initial “puppy series” of vaccinations, followed by a booster at one year and then boosters every 3 years thereafter, although specific vaccines and vaccination protocols can be controversial even within the veterinary community. Owners should discuss vaccines and vaccination schedules with their pet’s veterinarian to come up with a protocol that is appropriate for their dog.
Infectious canine hepatitis is very uncommon in dogs that have been properly vaccinated as puppies and that are kept up to date on their vaccinations according to the current vaccination protocols of the time. ICH is not a zoonotic disease, which means that it is not transmitted from dogs to people.