via aerosols and causes respiratory illness. equine h3n8 perferentially binds to α-2,3 sialic acids, so horses are usually considered dead-end hosts, but transmission to dogs and camels has occurred, raising concerns that horses may be mixing vessels for reassortment. in canines, the only iavs in circulation are equine-derived h3n8 and avian-derived h3n2. canine h3n8 has not been observed to reassort with other subtypes. h3n2 has a much broader host range and can reassort with h1n1 and h5n1. an isolated case of h6n1 likely from a chicken was found infecting a dog, so other aivs may emerge in canines. other mammals to be infected by iavs include h7n7 and h4n5 in seals, h1n3 in whales, and h10n4 and h3n2 in minks. various mutations have been identified that are associated with aivs adapting to mammals. since ha proteins vary in which sialic acids they bind to, mutations in the ha receptor binding site can allow aivs to infect mammals. other mutations include mutations affecting which sialic acids na proteins cleave and a mutation in the pb2 polymerase subunit that improves tolerance of lower temperatures in mammalian respiratory tracts and enhances rnp assembly by stabilizing np and pb2 binding. ibv is mainly found in humans but has also been detected in pigs, dogs, horses, and seals. likewise, icv primarily infects humans but has been observed in pigs, dogs, cattle, and dromedary camels. idv causes an influenza-like illness in pigs but its impact in its natural reservoir, cattle, is relatively unknown. it may cause respiratory disease resembling human influenza on its own, or it may be part of a bovine respiratory disease (brd) complex with other pathogens during co-infection. brd is a concern for the cattle industry, so idv's possible involvement in brd has led to research on vaccines for cattle that can provide protection against idv. two antigenic lineages are in circulation: d/swine/oklahoma/1334/2011 (d/ok) and d/bovine/oklahoma/660/2013 (d/660).