Canine influenza virus (H3N8 and H3N2), also known as dog flu is a highly-contagious respiratory disease in dogs. Originally affecting only horses, in 2004, cases of an unknown respiratory illness in dogs (initially greyhounds) were reported in the United States. An investigation showed that this respiratory illness was caused by equine influenza A (H3N8) viruses. Scientists believe this virus jumped species from horses to dogs and has now adapted to cause illness in dogs and spread among dogs, especially those housed in kennels and shelters.

How Is It Spread?

Like many viruses, canine influenza is spread through respiratory secretions and contaminated surfaces of everything from food and water bowls to leashes to toys. The virus can stay alive up to 48 hours on surfaces, 24 hours on clothing, and up to 12 hours on hands. If a dog comes in contact with the virus, it can be 2-4 days before it exhibits signs of feeling ill, and the dog is also most contagious during this time.

What are signs of canine influenza in dogs?

All dogs regardless of breed, size, or age can contract the virus. Because the virus is relatively new in dogs, most have no immunity to it. The signs of this illness in dogs are cough, runny nose, fever, lethargy, eye discharge, and reduced appetite, but not all dogs will show signs of illness. The severity of illness associated with canine flu in dogs can range from no signs to severe illness resulting in pneumonia and sometimes death. Anyone with concerns about their pet’s health, or whose pet is showing signs of canine influenza, should contact their veterinarian.

Treatment

Like with any virus, antibiotics and other drugs aren’t effective. Treatment largely consists of supportive care which helps to keep the dog hydrated and comfortable while its body then mounts an immune response to the infection to facilitate recovery. Although, sometimes dogs can get a secondary bacterial infection, in which case bactericidal antimicrobials are usually prescribed.

Prevention and Control

The virus seems to be easily killed by commonly used disinfectant solutions. Any dog who appears to display signs of respiratory disease or cough should be separated and consult your veterinarian to develop a course of action. If your dog is outwardly showing signs of the virus, speak to your veterinarian before taking your dog to their practice. They may not want your dog entering through the waiting area in case of infecting other dogs.

There are vaccines available for both the H3N8 and H3N2 strains of canine influenza. Speak to your veterinarian to discuss if you pet is a good fit. Your vet may recommend the vaccine based on your lifestyle. For instance, if you live in an area with a high incidence of dog flu or if your dog regularly spends time in kennels.

Can canine influenza viruses infect people?

In general, canine influenza viruses are thought to pose a low threat to people. To date, there is no evidence of spread of canine influenza viruses from dogs to people and there has not been a single reported case of human infection with a canine influenza virus in the U.S. or worldwide. However, influenza viruses are constantly changing and it is possible that a canine influenza virus could change so that it could infect people and spread easily between people.