Canine influenza (CIV) doesn’t affect people (or cats), but infected dogs experience symptoms such as coughing, respiratory infection, and fever. The available vaccine won’t necessarily prevent a dog from getting the flu, but it is helpful in reducing the severity of the illness should a dog become infected.


This new, highly transmissible virus was first detected in 2004 among a group of racing greyhounds in Florida. Investigators eventually learned that canine influenza developed when an equine influenza virus adapted to infect dogs. This represented a rare event, because the new virus was canine specific (only transmissible to other dogs).

CIV has caused localized disease outbreaks around the United States and has been reported in more than 30 states plus the District of Columbia. It’s spread between dogs through direct contact (coughing, sneezing, facial licking) or indirect contact (contaminated bowls, leashes, collars, or the hands or clothing of people who handle ill dogs).

The bad news: Virtually all dogs exposed to CIV become infected; however, 20 percent of dogs don’t show signs but can still spread the virus.

The good news: CIV does not infect people, and, so far, there’s no documentation that cats have become infected by exposure to infected dogs.

Symptoms and Identification

Signs of respiratory infection (coughing, nasal discharge) are most commonly associated with CIV. However, some dogs become severely ill and develop a high fever, difficulty breathing, or pneumonia.

Infected dogs usually develop signs of illness within two to four days of having been exposed. Typical locations for exposure include kennels, hospitals, grooming salons, or dog parks.

Unfortunately, canine influenza can’t be diagnosed by signs alone because the signs are similar to those of other respiratory illnesses in dogs (kennel cough syndrome, for example). For dogs that have been sick for a short time, veterinarians can swab the nose or throat and submit samples to a diagnostic laboratory for analysis. Specific blood testing can also be helpful in making a diagnosis.

Affected Breeds

This infectious disease knows no breed limits. If exposed, all dogs are at risk of infection.


Treatment mostly involves supportive care, which may include fluid therapy, antibiotics (to treat any secondary bacterial infections), and cough medications. Seriously ill dogs may require hospitalization, but most affected dogs need only be quarantined at home while potentially contagious (about two weeks).


Any time dogs congregate with other dogs it increases their risk of exposure to CIV so that owners should be on the lookout for any news of a local outbreak. In this event, dogs should not be allowed to have casual contact with unknown dogs until the outbreak has been reported controlled.

Ask kennel owners, groomers, show event managers, and your veterinarian what their facilities’ policies are regarding disinfection, quarantine, and disease prevention. As with human influenza, frequent hand washing and disinfection may help prevent the spread of CIV.

In May 2009, the United States Department of Agriculture approved the first canine influenza vaccine. It may not prevent infection, but vaccinated dogs usually don’t become as sick as unvaccinated dogs and do recover more quickly. The vaccine is useful for dogs that may be exposed to high-risk environments, such as kennels, boarding facilities, dog parks, or dog shows. Ask your veterinarian whether your dog should be vaccinated against canine influenza.

This article has been reviewed by a Veterinarian.