Infectious Hepatitis in Dogs
Infectious canine hepatitis is a highly contagious viral infection that affects the liver, kidneys, spleen, lungs, and eyes in dogs. It occurs worldwide, though it is rare in the United States, and it mostly affects young dogs under one year of age, though it can affect adults. Most cases occur in wild or unvaccinated dogs.
Signs & Symptoms of Infectious Canine Hepatitis
This disease can cause a very wide range of signs and symptoms. These can range from mild to severe:
- Sore throat
- Difficulty clotting blood, as displayed by bleeding around the teeth or spontaneous hematomas in the mouth
- Cloudiness of eye ("hepatitis blue eye") in 25% of cases, and usually in dogs under six months old
- Drinking and urinating a lot
- Light colored stool
- Loss of appetite
- Abdominal pain and enlargement
- Swollen lymph nodes
- Swelling of tonsils, head, neck, or trunk
- Weight loss
- Pale tongue, gums, and nose
- Fever of greater than 104°F lasting one to six days in dogs under one year of age
In mild cases, your dog will display a mild fever, moderate lethargy, and slight loss of appetite. In this case, your dog will usually recover on its own in about two days.
In more severe cases, your dog can develop a biphasic fever (a fever associated with two different sets of symptoms as it progresses) for one to six days, pass bloody diarrhea or bloody vomit, tuck up their belly from pain associated with the liver, become sensitive to light (which may cause tearing or squinting), and refuse to eat. Death can occur within a few hours and veterinary attention will need to be sought immediately.
The fatal form of the disease results in a sudden onset of severe symptoms. Bleeding from the nose and gums, enlarged abdomen due to fluid leaking from the liver, bloody diarrhea and vomit, seizures due to central nervous system association, disorientation, coma, and death may occur. Dogs may die suddenly without any obvious illness. Infectious canine hepatitis is most severe, and the mortality rate is highest, in young dogs. Veterinary attention will need to be sought immediately.
Causes of Infectious Canine Hepatitis
Infectious canine hepatitis is caused by a virus known as the canine adenovirus-1 or (CAV-1). This virus is a resilient virus, able to survive outside of the host for weeks or months, and may only be killed using certain disinfectants. Your dog can contract CAV-1 virus through direct contact with infected saliva, urine, or feces, either with your dog’s mouth or nose. Even a dog dish that has been licked clean can carry the virus. The tonsils and lymph nodes are the first body parts affected. The incubation period can last four to nine days, after which the virus enters the bloodstream.
Diagnosis of Infectious Canine Hepatitis
Diagnosis begins with a complete history and a physical exam. There are several different tests used to diagnose canine hepatitis. The diagnostic path chosen will depend largely on the symptoms your dog has and the availability of diagnostic tools your veterinarian has. Your veterinarian will be most likely to do the following:
- CBC/Chemistry Panel - These blood tests will evaluate various internal organ functions, including the heart, liver, kidneys, pancreas, metabolism, and electrolyte balance. The CBC will measure the amount and different kinds of red and white blood cells that are present in the bloodstream. If your dog has infectious canine hepatitis, a low white blood cell count and elevated liver enzymes would be found.
- ELISA testing - This stands for "enzyme-linked immunosorbent assay," and is a test used to determine if a dog has been exposed to a certain pathogen by seeing if the dog’s body has produced antibodies against the pathogen. It can be used to test for viruses, bacteria, microbes, or other material. In this case, the veterinarian would take a fecal sample and test it for the antibodies of the canine adenovirus-1.
- Immunofluorescence - This is a technique used to illuminate either viruses or their antibodies in a tissue or culture using a fluorescent dye. In this case, your veterinarian will make a tissue or cell smear and expose it to a virus-specific antibody for infectious canine hepatitis. The antibody will attach to any virus displayed in the sample and show under a microscope as a bright green spot on the slide.
Because of the wide variety of symptoms associated with this disease, your veterinarian might want to do other tests to differentiate this disease from others. This disease is commonly mistaken for distemper because of the low white blood cell count and biphasic fever, as well as parvovirus because of the low white blood cell count and diarrhea.
Treatment for Infectious Canine Hepatitis
Your veterinarian will likely treat infectious canine hepatitis according to the symptoms being displayed:
- A broad spectrum antibiotic may be administered.
- IV fluids, along with a dextrose solution, might be administered to rehydrate the dog.
- Blood transfusion may be necessary in severely ill dogs to replenish lost blood.
- The cloudiness of the eye will usually take care of itself, but an ointment may be given to relieve your dog from eye pain and light sensitivity.
- A fasting period may be instituted, followed by a light diet consisting of small, frequent meals.
Even after recovery, your dog can shed the virus in his urine for up to nine months. After recovering from the condition, the liver will completely recover, but long-term kidney damage, and prolonged eye cloudiness or glaucoma, may result as a delayed inflammation response. However, your dog will have lifelong immunity to the virus.
Prevention of Infectious Canine Hepatitis
- Vaccination is the most recommended method of preventing infectious canine hepatitis. While it seems logical to vaccinate using the CAV-1 virus, this can usually cause unwanted side effects, such as the bluing of the eye and the shedding of virus. Vaccination with a very closely related virus, CAV-2, is much safer, and will help your dog build immunity against CAV-1. CAV-2 is also thought to play a part in a common condition called kennel cough, so vaccinating with CAV-2 would result in immunity to both conditions. This vaccine is usually mixed with the distemper and parvovirus vaccine given to puppies within the first months of life. Annual revaccination is often recommended.
- Your young or unvaccinated dog should be kept away from public places, dogs outside your household, or dirty food bowls that are left outside or belonging to dogs outside your household. Keep an eye on your dog during walks to ensure he/she does not consume urine or feces.
- Disinfection of contaminated areas with a bleach or iodine solution can kill the virus.