Infection of dogs with equine influenza virus: evidence for transmission from horses during the Australian outbreak.

During the equine influenza (EI) outbreak, respiratory disease was observed in dogs that were in close proximity to infected horses. Investigations were undertaken to exclude influenza virus infection. Of the 23 dogs that were seropositive in tests using the influenza A/Sydney/2007 virus as the test antigen, 10 showed clinical signs. EI virus appeared to be readily transmitted to dogs that were held in close proximity to infected horses, but there was no evidence of lateral transmission of the virus to other dogs that did not have contact with or were not held in close proximity to horses.