Influenza A viruses (IAV) are primarily pathogens of avian species, but spillovers into mammals have contributed to significant disease burden in those hosts. IAVs in human populations (H1N1, H2N2, H3N2) are well known for their past pandemics and endemic spread as a seasonal respiratory disease. Yet, many non-human mammalian hosts have also suffered epizootic outbreaks and bare continually circulating subtypes. These include horses and dogs, that may frequently come into contact with humans.

We are interested in the natural history of the different influenza viruses that infect dogs and horses, their properties, and how they might be controlled. We provide an introduction to these animal influenza viruses below, and also links to pages that include the specific information about the H3N2 canine influenza virus, and the H3N8 equine influenza virus.

Influenza general properties. Influenza viruses are members of the Orthomyxovirus Family, which contains viruses that infect many different animals. The viruses of greatest interest are the Influenza A, B, C and D – of which the Influenza A viruses appear to be of greatest treat to mammals, including humans. The main reservoir of Influenza A viruses is found among birds, primarily those that live in flocks in fresh or salt water aquatic environments.Those viruses mainly infect the GI tract and are shed in the feces, so that they are transmitted through fecal-oral transmission. Those viruses may be transmitted to other bird species, as well as occasionally infecting mammals – and then going on to cause epidemics of infection and disease in mammals. Of the epidemics seen in mammals, those appear to be most frequently occuring in swine, as well as in humans and horses. Most recently outbreaks and epidemics have occured in dogs, after transfer from either horses or from birds.