Canine/Dog Flu Diagnosis

Canine dog flu can actually trace its origins to the equine influenza virus H3N8, which infected another specie (canine), a rare occurrence. Since dogs had not previously been exposed to this strain of Influenza virus A, they had no immunity resulting in the disease to spread rapidly between individual dogs. Canine influenza is endemic to some regional United States dog population, such as racing greyhounds, who were the first to contract this disease, being exposed by racehorses by using the same racetrack. It has a high morbidity rate, but a low mortality rate.

Symptoms of Dog Flu

Any dog exposed to the virus will become infected; however, only approximately 80% develop any clinical signs. The other 20% do not exhibit clinical signs but are still capable of shedding the virus and spreading the disease. For those dogs that develop pneumonia secondary to the dog flu, fatality rates can reach 50% if untreated.

Mild Symptoms of the Flu in Dogs

  • A cough lasting from 10 to 30 days, despite treatments with antibiotics and/or cough suppressants
  • A dry cough resembling kennel cough by a dog that has been vaccinated for such
  • A soft, moist (productive) cough lasting more than 10 to 30 days
  • Greenish nasal discharge
  • Upper respiratory tract infection
  • Low grade fever
  • Sneezing
  • Development of a flu occurring year-round (not seasonal)

Severe Symptoms of Flu in Canines

  • Pneumonia resulting from a secondary infection
  • High fever (104 degrees F to 106 degrees F)
  • Increased respiratory rate
  • Increased respiratory effort
  • Chest x-rays revealing consolidation of lung lobes

Since the virus infects and replicates inside the respiratory tract cells (nasal lining to airways), rhinitis, bronchitis tracheititis and bronchiolitis can result. The cells of the outer lining of the respiratory tract die, leaving the underlying membrane exposed and susceptible to infections.


Canine flu is spread from dog to dog in various ways:

  • Via respiratory secretions, such as sneeze, cough or nasal discharges
  • Via contaminated objects, such as food and water bowls, surfaces, collars, leashes
  • Via people moving between infected and uninfected dogs without washing their hands first

This virus can remain viable (alive and is capable of infecting) for 48 hours on surfaces, for 24 hours on clothing and for 12 hours on hands. The incubation period is 2 to 4 days whereby the dog is potentially contagious and capable of shedding the virus and spreading the disease during this time even without showing any symptoms. This shedding and spreading is still possible 7 to 10 days upon exposure to the disease.

Testing of nasal and throat swaps for the disease will confirm its existence coupled with the existence of the symptoms listed above. Isolation of all infected dogs is important in stopping the spread of the disease.

There is no specific treatment for canine flu, only treatment of the secondary infections. Antibiotics are used to treat secondary infections.

There is no evidence to suggest that canine flu is a risk to humans. However, greyhounds seem to be the only breed reported to have developed hemorrhagic pneumonia resulting in death.