Canine Influenza

Canine Influenza

According to the CDC (Centers for Disease Control and Prevention), canine influenza, also referred to as dog flu, is a contagious respiratory disease in dogs caused by specific influenza viruses known to infect dogs. The American Veterinary Medical Association (AVMA) states that there are two strains of canine influenza: H3N8 and H3N2. Influenza type A (H3N8) was first identified in Florida in 2004. Since 2015, there have been reported cases of both H3N8 and H3N2 in New Jersey. From 2008 to 2015, the only reported cases were of H3N8.

“As of May 2018, there have been 61 positive cases of dog flu in New York City, NY and 1 positive case in Paramus, NJ.” –

Canine influenza is a highly contagious viral infection. Almost every dog that is exposed to the virus will become infected. According to the AVMA, the morbidity rate of canine influenza is high. 80% of exposed animals will develop the disease. However, the mortality rate is relatively low. Less than 10% of all infected dogs actually die from the disease.

Signs and Symptoms
Not all infected dogs will show signs of disease. About 80% of dogs develop clinical signs while 20% of infected dogs will show virtually no signs of disease. Although these dogs show no signs, they can still spread the disease to other dogs.

    Clinical Signs Include:

  • Cough
  • Runny nose
  • Fever
  • Lethargy
  • Eye discharge
  • Reduced appetite


Diagnosis and Recovery
Canine influenza cannot be diagnosed solely by the clinical symptoms. This is because the same symptoms are also present in other canine respiratory illnesses. There are tests available through your veterinarian to diagnose and identify the strains of canine influenza virus.

Most dogs recover within 2-3 weeks. However, some dogs develop secondary bacterial infections which may lead to more severe illness, including pneumonia. Your veterinarian will determine the best course of treatment for your dog. There are currently no antiviral drugs approved to treat influenza in dogs.

Dogs do not have a natural immunity to canine influenza because it is a newer virus. There is also no “season” for dog flu; it can infect any time of year.

How is it spread?
The virus is spread a few different ways: through direct contact, through coughing or sneezing, or through contaminated objects. It tends to spread through the respiratory droplets produced from coughing and sneezing. The virus can spread indirectly through objects like food and water bowls, collars, leashes, toys, or surfaces. It can also be spread through people that have come in contact with infected dogs. The virus can remain viable for up to 48 hours on surfaces, 24 hours on clothing, and 12 hours on hands. To reduce the risk of disease transmission, it is extremely important to clean and disinfect any contaminated surfaces, objects, clothing, and hands. Some high risk areas of infection are dog parks, day cares, boarding facilities, shelters, groomers, and other pet friendly locations. Mobile dogs – rescue dogs or dogs that travel with their owners – easily spread the virus. This is how the disease spreads from state to state.

Dogs are contagious for three to four days prior to showing symptoms and seven to 10 days after symptoms subside. This could span several weeks. It is recommended that to prevent transmission of the virus, infected dogs with H3N2, and any other dogs in the household should be isolated for four weeks.

There is no evidence that canine influenza can spread from infected dogs to humans. However, the virus can infect cats. Cats infected with H3N2 display signs of upper respiratory disease including nasal discharge, congestion, malaise, lip smacking, and excessive salivation. Most cats can recover at home without any complications. However, it is always best to visit your veterinarian to determine the best course of action.

Canine Influenza Vaccine
There is a vaccine for dogs to protect against canine influenza. Currently, there is no vaccine to protect cats from the virus. The canine influenza vaccine is considered a “lifestyle vaccine,” meaning it may not be recommended for all dogs. The vaccine is typically recommended for dogs at risk for exposure to the virus, including dogs that participate in activities with other dogs or dogs that are housed in communal facilities. Dogs that benefit from this vaccine include those that also receive the Bordetella (kennel cough) vaccine. Owners should consult with their veterinarian if the vaccine is right for their dog. Owners of boarding or day care facilities may require vaccination of dogs frequenting their establishments.


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