A strain of flu has sickened thousands of dogs in the Midwest. The canine influenza virus (CIV) started infecting dogs in Chicago in January and has spread to dogs in Illinois, Wisconsin, Ohio, and Indiana. Six dogs have died.
This virus is a strain called H3N2 and has been seen widely in China and South Korea. It has never been reported in the United States before this outbreak and it is not known how it reached Chicago. It possibly was carried by a dog from Asia that was infected but which did not show any symptoms.
H3N2 CIV does not affect people, but it can affect cats. It is a strain similar to the H3N8 dog flu, a strain that has been in the United States for some time and which was the cause of several deaths to racing greyhounds at a racetrack in Florida in 2004.
Like all forms of the flu, CIV can spread rapidly. It appears to cause deaths in less than 10% of cases. While the H3N8 version had a 5% to 8% mortality rate in racing greyhounds, its mortality has been lower in other populations of dogs. Most deaths occur in puppies or older dogs. However, as with the H3N8 strain, some dogs become infected, but don't get sick, or don't get sick enough to show symptoms.
Symptoms of the flu in dogs are similar to those in humans: a persistent cough, a runny nose, poor appetite, and a fever. Normal body temperature for a dog is between 101 and 102.5 degrees Fahrenheit.
There have been 1,137 reported cases of H3N2 CIV in the Chicago area, which is where the deaths have occurred. There is no information on how many cases may have occurred in the rest of the Midwest.
Veterinary health experts recommend having dogs be vaccinated against the flu. Pet owners in the affected areas should avoid bringing their dogs into close contact with other dogs.