The signs of canine influenza virus (CIV) infection are mild in most dogs and are similar to those of canine cough.

Pet care professionals must have a high index of suspicion to ensure appropriate identification, management, and prevention of disease transmission.

Disease Course and Prognosis

Because most dogs have not been exposed to canine influenza virus (CIV), virtually 100% of those exposed will be fully susceptible. The figure below shows the prevalence of morbidity and mortality in dogs infected with CIV. A subset of about 10 to 20% of dogs develop subclinical infection, but can still shed the virus and transmit disease to other dogs. Approximately 80 to 90% of exposed dogs develop clinical disease, with most of these having a mild disease course. Approximately 1 to 20% of dogs progress to the more severe form of the condition.²

The fatality rate related to pneumonia is reported to be 5 to 8% but, with rapid diagnosis and appropriate therapy, may be much lower.² Peracute fatal hemorrhagic pneumonia has been reported only in the Greyhound. The case fatality rate at one Greyhound track was reported to be 36%, but this is not expected in the general canine population.⁶