The viral disease can infect other animals including wolves and bears, says Yung-Tsun Lo (D.V.M., Ph.D) of Bioguard Corporation.
Infectious canine hepatitis (ICH) is a viral disease in dogs caused by the canine adenovirus type 1 (CAV-1). While it primarily targets the liver, ICH can also affect the kidneys, eyes, and blood vessels, leading to a variety of symptoms. Although CAV-1 does not pose a risk to humans, it can infect other animals, including wolves, coyotes, skunks and bears, and can cause encephalitis in foxes. ICH mainly affects dogs younger than one year old, but there have been cases in adult dogs prior to the widespread availability of vaccines.
Transmission
Transmission occurs mainly through oronasal exposure to saliva, faeces, urine, or nasal discharge from infected dogs. The virus can also spread via fomites, such as hands, utensils and clothing, as well as through ectoparasites like fleas and ticks.
The initial infection takes place through the nasopharyngeal, conjunctival, or oropharyngeal routes. Once inside, the virus replicates in the tonsil crypts and lymph nodes, leading to viremia and spreading to various organs, particularly the liver. Infected dogs can shed the virus in their urine for up to 6 to 9 months after infection. In older dogs, infections are generally mild or go unnoticed, often resolving without treatment.
Symptoms
ICH symptoms can vary from mild to severe, depending on the dog’s age, immune response and the virus’s virulence. Symptoms usually appear four to nine days after exposure, though many dogs may remain asymptomatic.
Common signs include:
- Fever and lethargy
- Vomiting and diarrhoea
- Loss of appetite
- Abdominal pain
- Enlarged tonsils
- Jaundice
- Cloudy or swollen eye, known as blue eye
- or corneal oedema
There are three primary disease syndromes linked to canine hepatitis:
Per acute Disease: A severe form that causes circulatory collapse, coagulation disorder, coma and death within 24 to 48 hours following a brief illness.
Acute Disease: The most frequently observed form, with high morbidity and a mortality rate of 10% to 30%. Dogs with acute disease either recover or succumb within two weeks.
Chronic Disease: Seen in dogs with partial immunity, this form results in liver failure, leading to death weeks (subacute) or months (chronic) after the initial infection.
Diagnosis
ICH should be suspected in dogs under one year of age with an unclear vaccination history who show signs of fever, bleeding disorders, or liver dysfunction, especially if corneal oedema is present. Definitive antemortem diagnosis is not required before supportive care is instituted; however, it can be pursued with ELISA, serologic and PCR tests.
Treatment
There is no specific treatment for CAV-1 infection, so management focuses on supporting the dog through the illness. Dogs that receive timely veterinary care may recover, but some may have long-term kidney or eye complications.
Treatment may include:
- IV fluids to prevent dehydration
- Blood transfusions to address coagulopathy
- Pain relief
- Anti-nausea medications
- Antibiotics to prevent secondary bacterial infections
- Nutritional support
Prevention
Vaccination is the most effective way to prevent infectious canine hepatitis. The ICH vaccine is usually part of combination vaccines, such as DHPP, which are given as core vaccinations for both puppies and adult dogs. Many vaccines use the CAV-2 strain instead of CAV-1, as it provides protection against viral hepatitis and certain types of kennel cough while minimizing the risk of “blue eye”.
Your veterinary surgeon will determine the best vaccination protocol based on your pet’s specific situation. Additionally, keeping your dog’s environment clean and reducing contact with potentially infected animals or areas can help lower the risk of infection.
