Canine influenza virus (technically referred to as canine influenza H3N2 since there are two strains of the virus) was first identified in the United States in 2015 in the Chicago area. And in January 2018, there was an outbreak in the San Jose area. Canine influenza is a highly contagious viral disease that can look similar to typical upper respiratory infection/kennel cough, with coughing, sneezing and lethargy. However, influenza can cause more serious disease that can result in pneumonia and, less commonly, death. It is contagious only to dogs, not to humans.
The incubation period of canine influenza is approximately two to four days from initial exposure to the flu virus. Viral shedding starts to decrease after the fourth day, but dogs with H3N2 remain contagious for up to 26 days. Most veterinarians recommend isolating dogs with H3N2 for at least 21 days to reduce the risk of transmission.