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Adenovirus in Dogs: What You Need to Know

7 min read

Updated - Sep 16th, 2022

Key Points

  • Canine adenovirus type 1 (CAV-1), rare among regularly vaccinated household pets, is responsible for infectious canine hepatitis, while canine adenovirus type 2 (CAV-2) is more common and causes respiratory disease in dogs. 
  • Dogs contract these viruses through contact with infected dogs’ saliva, mucus, urine, or feces.
  • Vaccination protects your dog from CAV-1 and severe forms of CAV-2.

It can be scary to hear your dog in a coughing fit. After all, coughing up a storm isn’t something a healthy pooch normally does. Sometimes, this can be a symptom of adenovirus.

Several pathogens are associated with the condition known as kennel cough, and one such cause is the adenovirus infection.

Two types of adenovirus cause infectious diseases in dogs:

Canine adenovirus type 1 is responsible for infectious canine hepatitis, a dangerous liver disease that can be fatal. Symptoms include fever, vomiting, diarrhea, a milky, opaque appearance to the eyes, and loss of appetite, among others.

Canine adenovirus type 2 causes infectious tracheobronchitis, more commonly referred to as “kennel cough.” Dogs with CAV-2 will likely exhibit a hacking cough, along with fever and nasal discharge.

There is no cure for CAV-1 or CAV-2, but effective treatment – which can include hospitalization for CAV-1 – can help mitigate the severity of symptoms. Vaccination is the best form of prevention against contracting canine adenovirus 1 and 2.

Symptoms

Your pup might have come down with CAV-2 – more common than its sister adenovirus, CAV-1 – if they exhibit the following symptoms:

  • A dry, hacking cough (often described as sounding like a “goose honk”)
  • Fever
  • Nasal secretions
  • Coughing up a white, foamy discharge
  • Ocular inflammation (conjunctivitis)
  • Retching or gagging

Signs your dog might have a mild form of infectious canine hepatitis – caused by CAV-1 – include decreased appetite, mild fever, respiratory secretions from the nose and eyes, and coughing. They might also seem depressed and, over a week or two, develop corneal edema, more commonly known as “blue eye,” which is a cloudiness that forms over the eyes due to lesions on the cornea.

Along with fever, loss of appetite, and depression, more severe cases of infectious canine hepatitis can exhibit the following clinical signs:

  • Abdominal pain
  • Vomiting
  • Diarrhea
  • Edema of the head and neck (fluid swelling under the skin)
  • Jaundice

Sadly, these symptoms can be fatal, especially in young dogs and puppies. Canine herpesvirus, which has similar clinical signs to infectious canine hepatitis caused by CAV-1, also primarily affects puppies and is often fatal.

On a positive note, if your dog recovers from infectious canine hepatitis, it is highly likely they will have immunity against CAV-1 for life.

Causes 

Canine adenovirus 1, which causes infectious canine hepatitis, is spread through direct contact with the urine, feces, respiratory secretions, or eye discharge of infected animals. Once contracted through the nose or mouth, the hepatitis virus localizes in the dog’s tonsils and then replicates in the lymph nodes, spreading into the bloodstream. Younger dogs are more susceptible to getting the virus and developing severe symptoms. Dogs sick with the disease can spread the virus, but so can those that have recently recovered or show no symptoms at all.

Canine adenovirus 2 causes an upper respiratory tract disease called infectious tracheobronchitis.  It spreads easily among dogs – most commonly through coughing, but your fur baby can also contract it just from sniffing an infected dog on a walk. Vaccination against canine adenovirus is the best way to keep your dog protected while still preserving their social life.

Diagnosis

Since several pathogens besides canine adenovirus 2 can cause kennel cough – including parainfluenza and the bacterium Bordetella bronchiseptica – your dog’s vet might confirm CAV-2 with a PCR test that looks for the presence of the canine adenovirus type 2 antigen. Peak viral replication occurs 3 to 6 days after infection, and the virus might not be detectable after 9 days, so it’s important that the swabs are taken as soon as possible after the onset of symptoms.

If your dog is exhibiting symptoms of canine adenovirus 1, visit the vet as soon as possible to ensure they receive the highest level of treatment. Your vet could suspect CAV-1 based on symptoms; however, because canine distemper and parvovirus manifest in similar symptoms, they will likely take blood and urine tests to determine the presence of CAV-1 and make a diagnosis of infectious canine hepatitis.

Other tests used to confirm a diagnosis of ICH include coagulation tests to check for clotting, serology for antibodies to CAV-1, and viral culture. Your vet might recommend radiography and/or ultrasonography on the abdomen to gain a detailed view of the liver and see whether it is enlarged or suffering from necrosis (cell death).

Treatment

As with most viral infections, there is no cure or specific treatment for infectious canine hepatitis and infectious tracheobronchitis caused by canine adenovirus. Your dog’s vet might prescribe antibiotics to prevent secondary bacterial infections, although this regimen won’t be effective against the virus itself. Cough suppressants and anti-inflammatory medications can help provide relief in some cases of infectious tracheobronchitis (kennel cough) caused by CAV-2.

Treatment for severe cases of infectious canine hepatitis can include hospitalization with the administration of an IV to supply fluids and balance electrolyte levels – important for increasing your pup’s chances of survival. Extreme cases can call for blood transfusions. Recovery will often depend on the severity of the disease.

Recovery and care

With plenty of rest and fluids, your pup should recover from canine adenovirus 2 in a few weeks. If mild clinical symptoms linger, contact your veterinarian. The CAV-2 virus can live on surfaces for at least 7 days, so disinfect any objects or surfaces in your home that might have come into contact with the virus.

If your dog is hospitalized for canine adenovirus 1, your vet will schedule follow-up visits to monitor fluid and electrolyte levels. They will likely monitor your dog’s kidneys to ensure the virus does not reappear in the renal epithelium and cause interstitial nephritis. Sometimes lesions can form on the interior organs of dogs that have recovered from severe forms of CAV-1 and tissue damage can occur, but neither of these usually presents a problem.

Your best furry pal will need a lot of TLC while recovering, including a highly digestible diet and a safe and comfortable place to rest. Limit your dog’s physical activity and keep other animals away from them. The virus can be shed long after recovery, so make sure to clean up your dog’s waste and disinfect their surroundings.

Prevention

A vaccinated pooch is a healthy pooch!

The CAV-2 vaccine is usually administered as part of a combination vaccine that also safeguards against canine parvovirus and canine distemper virus. Immunity against CAV-1 and CAV-2 wanes over time, so veterinarians recommend that dogs receive a booster every 3 years.

Tip: Puppies can’t get vaccinated against CAV-1 and CAV-2 until they’re 6 to 8 weeks of age. Vaccinations given before then will prove ineffective due to antibodies in their mother’s milk.

To keep young puppies healthy and safe, make sure to separate them from other dogs until they can get vaccinated. The population density in kennels and shelters can increase the risk of infection from CAV-2.

What to expect at the vet’s office

If you make an appointment based on symptoms of CAV-1 or CAV-2, be prepared to discuss your dog’s health and illness history with your vet, and describe the onset of symptoms and what might have led to your pet’s condition.

Infectious tracheobronchitis is usually diagnosed based on your dog’s symptoms and recent history, but your vet might perform a PCR test to confirm the presence of the CAV-2 antigen. If your vet suspects infectious canine hepatitis (caused by CAV-1), they will likely perform a thorough physical examination, standard laboratory work, and a complete blood profile.

The bottom line

Neither form of canine adenovirus is a walk in the park for your pooch. The best way to keep your dog safe is to vaccinate them against the virus.

FAQs

Does the same vaccine protect against CAV-1 and CAV-2?

The MLV (modified live virus) vaccine protects against CAV-1 and helps to prevent severe forms of CAV-2. However, the vaccine is not effective for life; booster shots are needed every few years. Consult your vet for a recommended puppy vaccination schedule.

How early can I vaccinate my puppy?

Puppies are eligible for the MLV vaccine of CAV-2 starting at 6 to 8 weeks old. Two booster shots – given 3 or 4 weeks apart – follow the initial vaccine, and then your pup receives an additional booster at age one.

Are certain dog breeds more susceptible to the virus?

All breeds are at risk of contracting canine adenovirus 1 and 2, so be sure to vaccinate your puppy or dog as soon as possible.

Did you know?

  • Canine adenovirus 1 is also found in populations of wild carnivores, including wolves, bears, skunks, coyotes, and foxes, and has been linked to cases of fox encephalitis.
  • While canine adenovirus affects dogs, different forms of adenovirus infect humans and often cause cold- or flu-like symptoms.
  • Pet insurance can help cover the cost of treatment for unexpected illnesses like infectious canine hepatitis and kennel cough. Fetch a free quote for a Pumpkin Pet Insurance plan today.


Erin is a writer and human mom to Rufus, an adorable, sometimes-curmudgeonly Irish terrier who loves peanut butter and is afraid of cats.