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Adenovirus 1 in Dogs

Infectious Canine Hepatitis in Dogs

Infectious Canine Hepatitis (ICH) is a viral illness caused by canine adenovirus CAV-1, a DNA virus known for causing upper respiratory tract infections in dogs. This virus targets vital organs such as the liver, kidneys, eyes, and endothelial cells lining blood vessels.

The virus initially localizes in the tonsils approximately 4 to 8 days following exposure through the nose and mouth. Subsequently, it spreads into the bloodstream, a condition referred to as viremia, and settles in the Kupffer cells found in the liver, as well as the liver’s endothelial cells. While Kupffer cells typically defend the body against pathogens, certain viruses, like CAV-1, exploit them for replication and dissemination, causing damage to nearby hepatocytes responsible for various metabolic functions.

During this infection phase, the virus is shed into both feces and saliva, rendering them infectious to other dogs. In a healthy dog with a robust antibody response, the virus clears from the organs within 10 to 14 days but remains localized in the kidneys, where it continues to be shed in the urine for 6 to 9 months.

In cases where dogs mount only a partial neutralizing antibody response, chronic hepatitis ensues. This severe condition often leads to cytotoxic ocular injuries due to inflammation and cell death in the eye, resulting in anterior uveitis. This condition is characterized by one of the hallmark signs of infectious hepatitis: “hepatitis blue eye.”

CAV-1 infection does not exhibit breed, genetic, or gender predispositions but is commonly observed in dogs younger than one year old.


The symptoms of Infectious Canine Hepatitis (ICH) vary depending on the immunological condition of the host and the extent of initial cell injury (cytotoxic):

  • Peracute (very severe) stage: Symptoms include fever, signs of central nervous system involvement, collapse of blood vessels, and a coagulation disorder known as Disseminated Intravascular Coagulation (DIC). Death often occurs within hours.
  • Acute (severe) stage: Signs encompass fever, loss of appetite, lethargy, vomiting, diarrhea, liver enlargement, abdominal pain, accumulation of fluid in the abdomen, inflammation of blood vessels (vasculitis), pinpoint red spots on the skin (petechiae), bruising of the skin, DIC, swollen lymph nodes (lymphadenopathy), and occasionally, inflammation of the brain (nonsuppurative encephalitis).
  • Uncomplicated infection: Manifestations include lethargy, loss of appetite, temporary fever, tonsillitis, vomiting, diarrhea, swollen lymph nodes, enlarged liver, and abdominal pain.
  • Late stage infection: About 20 percent of cases may develop eye inflammation and corneal swelling four to six days after infection. Recovery often occurs within 21 days, but there is a risk of progression to conditions such as glaucoma and corneal ulceration.


  • Contact with infectious CAV-1 adenovirus
  • Unvaccinated dogs are at highest risk


To properly diagnose your dog’s condition, it’s important to provide a detailed history of its health, symptoms onset, past illnesses, and any incidents that might be relevant. Exposure to other dogs, such as in kennels, or contact with feces in areas where dogs defecate could be factors in contracting the virus.

Your vet will conduct a comprehensive physical examination of your dog and order standard laboratory tests. This will include a complete blood profile, chemical blood profile, complete blood count, urinalysis, and electrolyte panel. To confirm a diagnosis of infectious hepatitis, additional tests such as coagulation tests to assess blood clotting function, serology for antibodies to CAV-1, viral isolation, and viral culture will be necessary. Your vet will also screen for other common diseases like parvovirus and distemper.

Imaging studies will involve abdominal radiography to check for liver enlargement (hepatomegaly) and fluid accumulation in the abdomen. Abdominal ultrasonography provides a more detailed view of the liver, helping to detect enlargement or necrosis (cell death). Ultrasonography is particularly useful if abdominal swelling is present, as it can overcome limitations posed by fluid obstruction in radiography. Ultrasonic imaging assesses tissue characteristics based on echo depth and frequency, revealing features such as decreased echo (hypoechoic) in liver tissue death or absence of echoes (anechoic) in severe abdominal fluid buildup.

A liver biopsy might also be necessary to confirm the diagnosis conclusively.


For cases in the early stages of infection that are uncomplicated, outpatient treatment may suffice. However, typically, treatment is administered on an inpatient basis. Fluid therapy aims to address electrolyte imbalances resulting from vomiting and diarrhea, with immediate supplementation of potassium and magnesium when levels are critically low. Coagulopathy necessitates blood component therapy, especially in cases of overt DIC (disseminated intravascular coagulation), where stabilizing the dog’s condition involves fresh blood products and low molecular weight heparin.

Nutritional support involves offering frequent small meals as tolerated, optimizing nitrogen intake, and adjusting protein intake based on the individual condition of the dog. Inappropriate protein restriction can hinder tissue repair and regeneration. If hepatic encephalopathy is evident, nitrogen intake must be moderated. Partial intravenous nutrition is an option for up to five days, with total intravenous nutrition preferred if oral feeding is not feasible for the dog. Antibiotics and fluid reducers will be prescribed as deemed necessary by the attending veterinarian.

Living and Management

After treatment, your veterinarian will schedule follow-up appointments to monitor your dog’s fluid balance, electrolyte levels, acid-base balance, and coagulation status. Monitoring for sudden kidney failure is also essential. During recovery, it’s important to feed your dog a highly digestible diet and provide a quiet, safe environment for rest. Limit your dog’s activity and separate them from other pets during the recovery period. Maintain strict hygiene practices as the virus can still be shed even after recovery.

Preventing this infection involves administering a modified live virus vaccination to your dog at six to eight weeks of age. This initial vaccination should be followed by two booster shots, given three to four weeks apart, until the dog reaches 16 weeks of age. An additional booster should be given at one year. This vaccination protocol is highly effective in preventing the disease.

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