Canine influenza, otherwise known as “dog flu”, is an extremely contagious infection.  There are now two strains of the virus that are affecting canines, H3N8 and H3N2.  While the H3N8 strain was first noted in Florida in 2004, this new strain (H3N2) originated in Korea, China, and Thailand and was not seen in the United States until March of 2015.

Almost 80% of dogs that are exposed will develop symptoms.

Canine influenza virus is spread by coughing, barking, sneezing.  The virus can remain on surfaces for up to 48 hours, on clothing for 24 hours, and on hands for 12 hours.  Symptoms take 2-4 days to occur after exposure and it is during this time, when no symptoms exist, that dogs are most contagious.  Dogs have no natural immunity to the virus.  Almost 80% of dogs that are exposed will develop symptoms, most mild, but some can develop severe pneumonia.  The other 20% of exposed dogs will not develop symptoms but can still spread the virus.


Symptoms of canine influenza range from a mild cough, discharge from the eyes and nose, sneezing, and mild fever to severe fever and pneumonia. Because of the large range of symptoms, Canine influenza can be difficult to distinguish from other diseases that cause “kennel cough” like symptoms and diagnosis cannot be made on physical examination alone and requires special testing.


Treatment for canine influenza is all about supportive care.   Recovery can take 2-3 weeks as the dogs’ immune system mounts a response.  Supportive treatments may include fluids to help with dehydration, antibiotics to treat secondary infections, or medications to reduce fever.

As with most viral infections, preventing the infection is the most important step, especially since shedding of the virus occurs before symptoms.  Caring Hands Animal Hospital suggests that all dogs that are at risk of being exposed to the virus be vaccinated against it.

Is your dog at risk?

Dogs that are at risk are those that are regularly exposed to other dogs, such as boarding facilities, dog parks, grooming facilities, or other social events with other dogs present.  Caring Hands Animal Hospital has been carrying the vaccine for H3N8 for a long time, but we are now carrying the vaccine the H3N2 strain.

Unfortunately, there is no cross protection between vaccines and dogs that are at risk are advised to get vaccinated against both strains.  Once a dog is exhibiting signs of canine influenza, the dog should be isolated for 2 weeks and protective clothing should be worn to prevent the spread of the virus.  Thorough washing of hands and disinfecting of the environment are also important steps in the spread of this disease.

If you have more questions regarding the canine influenza virus, please visit the AVMA website or call to speak with a staff member at Caring Hands Animal Hospital.