Infectious Canine Hepatitis in Dogs

See your vet immediately if you think your dog may have infectious canine hepatitis. This disease is caused by canine adenovirus type 1, often shortened to CAV-1. It is a contagious viral infection that mainly targets the liver, but it can also damage blood vessels, kidneys, and other tissues. Signs can range from mild fever and low energy to severe bleeding problems, liver failure, and sudden death.

Infectious canine hepatitis is much less common than it once was because vaccination has been so effective. Even so, it still matters, especially in puppies, unvaccinated dogs, dogs from shelters or unknown vaccine backgrounds, and dogs exposed to contaminated urine, saliva, or feces. Foxes and some other wild canids can also carry related infection risks, which is one reason your vet may think about this disease even when it seems uncommon.

One tricky part of this illness is that early signs can look like many other problems, including parvovirus, leptospirosis, toxin exposure, pancreatitis, or other causes of acute liver disease. Dogs may start with fever, poor appetite, vomiting, or diarrhea, then worsen quickly if the liver and clotting system become involved. Some dogs also develop a cloudy blue eye during recovery, sometimes called “blue eye,” due to immune-related inflammation in the cornea.

Because there is no single at-home way to confirm the disease, prompt veterinary evaluation matters. Your vet may recommend bloodwork, clotting tests, urinalysis, imaging, and specific infectious disease testing. Fast supportive care can make a major difference, and prevention through routine core vaccination remains the most important long-term protection.

Your vet will diagnose infectious canine hepatitis by combining history, exam findings, and testing. Vaccine history is especially important. A young or unvaccinated dog with fever, vomiting, abdominal pain, low white blood cell counts, liver enzyme changes, or bleeding signs may raise concern for CAV-1 infection. Because many illnesses can look similar, diagnosis usually starts with broad testing rather than one single test.

Common first-line tests include a complete blood count, chemistry panel, urinalysis, and often clotting tests. These can show low white blood cells early in disease, liver injury, bilirubin changes, kidney involvement, or evidence of coagulopathy. Your vet may also recommend abdominal imaging to look at the liver, gallbladder, and other organs, especially if your dog has pain, jaundice, or concern for internal bleeding.

Specific confirmation can be more challenging. Merck notes that diagnosis may be confirmed with virus isolation, immunofluorescence, PCR, fluorescence in situ hybridization, or identification of characteristic intranuclear inclusion bodies in liver tissue. In real-world practice, your vet may use PCR or send samples to a diagnostic lab, while also ruling out other urgent conditions such as leptospirosis, parvovirus, toxin exposure, pancreatitis, or other causes of acute hepatitis.

In some cases, a definite answer is not available on the first visit, and treatment starts while test results are pending. That is common in emergency medicine. If your dog is unstable, your vet will focus first on hydration, clotting support, pain control, and monitoring while continuing the diagnostic workup.

Infectious canine hepatitis is caused by canine adenovirus type 1. After exposure through the nose or mouth, the virus spreads through the bloodstream and targets tissues including the liver and the lining of blood vessels. That combination helps explain why affected dogs can have both hepatitis and bleeding or swelling problems. The virus can also involve the kidneys and eyes.

Transmission happens through contact with infected body fluids and contaminated environments. Urine is especially important because dogs can continue shedding virus in urine after recovery. Saliva and feces may also play a role early in infection. Shared bowls, kennel surfaces, runs, and close contact with infected dogs can increase exposure risk, especially where many dogs are housed together.

The biggest risk factor is lack of vaccination. Puppies are at higher risk because maternal antibodies fade over time, leaving a window of vulnerability before the vaccine series is complete. Dogs with unknown vaccine history, recent rescue or shelter intake, or inconsistent preventive care are also more likely to be exposed without protection. Wildlife reservoirs and exposure to infected canids may matter in some regions or outdoor settings.

It is also important to know what does not cause this disease. Infectious canine hepatitis is not the same as chronic hepatitis, copper-associated liver disease, or toxin-related liver injury. Those conditions can look similar, but they have different causes and different treatment plans. That is why your vet may recommend a broad workup before deciding which path fits your dog best.

Vaccination is the most effective way to prevent infectious canine hepatitis. Even though the disease is caused by CAV-1, modern core vaccines commonly use CAV-2 because it provides cross-protection while avoiding some of the problems linked to older CAV-1 vaccines. AAHA lists adenovirus vaccination as a core vaccine for dogs, and VCA notes that after the first annual booster, many dogs are revaccinated on a three-year schedule with an approved product, depending on label and your vet’s recommendation.

Puppies need a properly timed vaccine series because maternal antibodies can interfere with early doses. Adult dogs with unknown history may need a catch-up plan. If your dog is overdue, your vet can help decide whether to restart, boost, or use a tailored schedule based on age, lifestyle, and medical history.

Good hygiene also matters. Dogs recovering from infection may shed virus in urine, so prompt cleanup and careful disinfection are important. Avoid sharing bowls, toys, or elimination areas with exposed dogs until your vet says the risk has passed. In shelters, boarding settings, and multi-dog homes, isolation and sanitation help reduce spread.

Prevention is not only about vaccines. It also includes routine wellness care, asking about vaccine status before boarding or group play, and getting prompt veterinary attention when a dog develops fever, vomiting, bruising, or jaundice. Early action protects both the sick dog and other dogs in the household or community.

Prognosis depends on how sick the dog is at diagnosis, whether clotting problems or liver failure are present, and how quickly supportive care begins. Mild cases may recover with careful monitoring and supportive treatment. Severe cases can be life-threatening, especially in puppies or dogs that arrive already dehydrated, bleeding, or collapsed.

Recovery is not always linear. Some dogs improve over several days, while others develop complications such as corneal edema, ongoing liver abnormalities, or kidney-related issues. Dogs that survive the acute phase often do better, but they may still need repeat bloodwork and follow-up exams to make sure liver values, hydration, and clotting status are stabilizing.

At home, recovery usually means rest, medication exactly as directed by your vet, easy access to water, and a diet plan that matches the dog’s current liver and GI status. Your vet may recommend temporary activity restriction and separation from other dogs while shedding risk is still a concern. Recheck timing matters because dogs can look better before lab values fully normalize.

The good news is that widespread vaccination has made this disease far less common than in the past. That means many dogs today are protected before they are ever exposed. For dogs that do get sick, early recognition and a treatment plan matched to the family’s goals and the dog’s condition give the best chance for a good outcome.