Canine Influenza Last Updated: June 2014

Influenza is a viral disease that has long been known to affect birds and some mammals, but was only recently recognized in dogs. Each influenza virus is maintained in one or more related host species; however, host specificity is not absolute. A virus may occasionally infect other animals, or on rare occasions, become adapted to a new species. No influenza viruses were known to circulate in dogs until 2004-2006, when a virus caused outbreaks of severe and often fatal respiratory disease among racing greyhounds in the U.S. This virus was acquired from horses, and probably entered greyhound populations several years before these outbreaks. Although it has spread to other dogs since this time, the illness in these animals has been more typical of influenza. The most common syndrome is a relatively mild upper respiratory disease with a persistent cough. Pneumonia is possible, generally as the result of secondary infection with bacteria or mycoplasma, but uncommon. At present, infections tend to be seen mainly in animal shelters, kennels, dog day care facilities, or other sites where groups of susceptible dogs are in close contact. This virus does not seem to have spread widely in other pets, and it has not yet bee