Some more severe infections have been reported, possibly because the dogs were also infected with other respiratory pathogens. (www2.vet.cornell.edu)
Canine influenza can not be diagnosed based upon clinical signs alone, because the signs of this disease are virtually identical to those caused by other respiratory pathogens. (petwave.com)
Vaccination against other pathogens causing respiratory disease may help prevent more common respiratory pathogens from becoming secondary infections in a respiratory tract already compromised by influenza infection. (northcountryvet.com)