Canine Influenza Virus (Dog Flu)

Dog flu, also called canine influenza virus or CIV, infects dogs with a contagious respiratory disease. It is caused by influenza A virus which is similar to the viral strains causing influenza or the flu in people. In most cases, dog flu makes dogs feel uncomfortable and sick similar to how the flu makes people feel.

What is Canine Influenza?

In the United States there are two known strains of dog flu called:

• H3N8

• H3N2

The H3N8 strain came initially from horses and the virus spread from horses to dogs in 2004. The first outbreaks of this canine influenza virus (CIV) infected racing Greyhounds at a Florida race track.

The H3N2 strain originated in Asia and scientists suspect it spread from birds to dogs. This strain resulted in the 2015 and 2016 outbreaks of canine influenza in the Midwest and continues to spread and cause illness throughout the United States.

How does the Dog Flu spread?

Similar to the human form of influenza, dog flu is airborne and spread to non-infected dogs from infected dogs when they cough, bark and sneeze. The dog flu can also spread from contaminated things such as water bowls, collars, kennel surfaces, and through contact with people who have been in direct contact with an infected dog.

Canine influenza virus can live on skin and hands for 12 hours, on clothing for 24 hours, and on other surfaces for up to 48 hours. Unlike the flu in people, CIV is not seasonal and dogs can become infected at any time of the year.

Dogs in close contact with each other in places like kennels, grooming facilities, doggie daycare, and dog parks are at higher risk for getting dog flu as infected dogs will spread the virus through barking, coughing, or sneezing. Dogs are actually more contagious and begin spreading dog flu before they have any signs or symptoms.

How long are dogs with canine influenza contagious to other dogs?

The time between the first exposure to a dog with dog flu and when that dog begins showing signs is about 2-4 days. The virus begins shedding right away and the infected dog remains contagious for up to 10 days after exposure to H3N8, while dogs with H3N2 remain contagious for up to 26 days. Veterinarians recommend isolating or keeping infected dogs away from other dogs for a minimum of 21 days to decrease the risk of spreading the virus.

Approximately 20-25% of infected dogs will show no symptoms but can still spread the virus.

Dogs with heart and lung problems, senior dogs, and brachycephalic breeds such as Boston Terriers, Boxers, Pekingese, Pugs, and Shih Tzus have increased risk for CIV and may develop life-threatening pneumonia or lung infection. These dogs have an increased risk for serious complications, including death, and must therefore be treated right away. Treatment may include intensive care with oxygen support, fluid therapy, antibiotics, and more.

Symptoms of Canine Influenza Virus

Dogs with CIV have respiratory symptoms which can be similar to CIRDC/kennel cough, including:

• Coughing (wet or dry)

• Sneezing

• Discharge from the nose which can sometimes be green or yellow

• Runny eyes

• Fever

• Lethargy (decreased activity)

• Difficulty breathing

Diagnosing Canine Influenza

Suspect that your dog may have CIV or kennel cough? Let your veterinary office know when scheduling your sick dog’s appointment that they are showing signs of a respiratory infection. This is important because both can easily infect other dogs and you may be instructed to wait outside until your appointment time to keep your dog from spreading any illness to other dogs in the reception area.

Since CIV looks similar to other respiratory diseases it cannot be diagnosed based on clinical signs as listed above. There are specific CIV tests that require a nasal swab, while others require a blood sample. Other blood tests and x-rays help determine if a dog has pneumonia or other internal organ problems that need treatment.

Any dogs suspected of having CIV should be tested to monitor the spread of the virus in your area. Some states require veterinarians to report cases of CIV to their state agency to monitor the spread of the virus.

Treatment Options for Dogs with Canine Influenza

As with many viruses, there is no specific treatment or cure for CIV. Your dog will need supportive treatment and care as recommended by your vet. Your vet will determine a treatment plan that may include fluid therapy, medication for fever and general discomfort, or antibiotics to treat secondary bacterial infections.

Dogs diagnosed with CIV will need to be quarantined to prevent spreading the virus. It is important to practice good hygiene and cleaning using disinfectant solutions that kill the canine influenza virus.

How can I protect my dog against CIV?

Keep your dog away from other dogs in common places such as dog parks, boarding kennels, or doggie daycare facilities especially if there is a CIV outbreak in your area. Any time you have been in contact with another dog, practice good hygiene by washing your hands, arms, and clothing before touching your own dog to decrease the chance of spreading the disease.

Veterinarians will recommend vaccinating against CIV for dogs at risk for infection such as dogs that board often, travel to dog shows, or spend time at doggie daycare.

The best way to prevent influenza in dogs is by vaccinating those at increased risk of exposure and by quarantining dogs that are positive for CIV.

Can people get the flu from a dog with canine influenza?

At this time people cannot become infected with CIV from their dog. If your dog is diagnosed with CIV, always practice good hygiene including hand washing, changing your clothes, etc. before coming in contact with another dog.

When to Call the Vet

If you notice any signs of respiratory illness in your dog, including those listed above, you should always contact your primary vet for advice and treatment recommendations.

Read more:

Common Causes of Coughing in Dogs

What You Need to Know About Vaccinating Your Dog

Caring for Pets with Pneumonia

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