Canine influenza virus (CIV) is an enveloped virus belonging to the genus Influenza virus A within the family Orthomyxoviridae. Prior to 2004, only sporadic outbreaks of canine influenza had been observed in dog populations around the world. However, in 2004 an H3N8 influenza virus of equine origin caused severe respiratory disease in racing greyhounds in Florida; subsequently, cases of dogs affected with various subtypes of CIV have been reported in many countries. Here, we performed a structured review of CIV, including its emergence, evolution and epizootiology. Although CIV causes a disease of low mortality, the potential public health threat it poses due to close contact between dogs and humans highlights the necessity of promoting surveillance for this virus.
Keywords: Canine influenza virus; epizootiology; origin; virulence.