Pigs, people and now pets.
D000818:Animals; D000829:Animals, Domestic; D002371:Cat Diseases / Q000453:epidemiology / Q000821:virology*; D002415:Cats; D005289:Ferrets; D053118:Influenza A Virus, H1N1 Subtype; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D014481:United States