What is canine influenza (dog flu)?
Dog flu is a contagious respiratory disease in dogs caused by a specific Type A influenza virus referred to as a “canine influenza virus.” This is a disease of dogs, not of humans.
The “canine influenza virus” is an influenza A H3N8 influenza virus (not a human influenza virus) that was originally an equine (horse) influenza virus. This virus has spread to dogs and can now spread between dogs.
The H3N8 equine influenza virus has been known to exist in horses for more than 40 years. In 2004, however, cases of an unknown respiratory illness in dogs (initially greyhounds) were reported. An investigation showed that this respiratory illness was caused by the equine influenza A H3N8 virus. Scientists believe that this virus jumped species (from horses to dogs) and has now adapted to cause illness in dogs and spread among dogs housed in kennels and shelters. This is now considered a dog-specific lineage of H3N8. In September of 2005, this virus was identified by experts as “a newly emerging pathogen in the dog population” in the United States.
The signs of this illness in dogs are cough, runny nose and fever, however, a small proportion of dogs can develop severe disease.
The percentage of dogs infected with this disease that die is very small. Some dogs have asymptomatic infections (no signs), while some have severe infections. Severe illness is characterized by the onset of pneumonia. Although this is a relatively new cause of disease in dogs and nearly all dogs are susceptible to infection, about 80 percent of infected dogs will have a mild form of disease.
Canine influenza virus can be spread to other dogs by direct contact with aerosolized respiratory secretions from infected dogs, by uninfected dogs coming into contact with contaminated objects, and by moving contaminated objects or materials between infected and uninfected dogs. Therefore, dog owners whose dogs are coughing or showing other signs of respiratory disease should not expose other dogs to the virus. Clothing, equipment, surfaces, and hands should be cleaned and disinfected after exposure to dogs showing signs of respiratory disease.
Read more at www.cdc.gov www.doginfluenza.com or www.merck-animal-health-usa.com