Dog flu or canine influenza?

By Jeff Castle

Many pet owners probably saw the recent stories on television about an epidemic outbreak of dog flu. Hopefully I can put some minds at ease. Dog flu is not the same as human flu.

Dog flu is a contagious respiratory virus of dogs. There have been two canine influenza viruses identified worldwide: the Influenza A H3N8 virus and the Influenza A H3N2 virus. No human infections with either of these canine influenza viruses have ever been reported.

The dog flu originated from the H3N8 Influenza virus of horses. The horse influenza virus has been around for approximately 40 years. In 2004, the first case of the influenza virus was found in a dog. It was reported in greyhounds in Florida. Researchers believe that the horse influenza virus “jumped” species and began to infect dogs.

Basically, there are two different forms of the virus. The most common is the mild form that only causes mild symptoms. The least common is the form that causes severe illness and some deaths. However, since the virus is relatively new, most dogs are susceptible to infection.

The most common symptoms of dog flu are coughing, runny nose and fever. Fortunately, approximately 80 percent of dogs with the virus have only very mild symptoms and recover well.

A very small percentage of dogs become very ill and die from pneumonia. Many dogs have the virus and show no signs of illness.

The dog flu is spread from dog to dog by direct contact with airborne particles when a sick dog coughs or sneezes. It is also possible for the secretions from a sick dog to contaminate objects such as one’s clothing, toys or bedding. If a dog is known to be infected, it is important to disinfect such objects and prevent exposure of other dogs to the infected dog.

Diagnosis of dog influenza is primarily from clinical signs and has to be differentiated from the more common and less serious canine kennel cough. Kennel cough is a term used to describe an infectious and contagious condition of the upper respiratory system of dogs. The more accurate medical term for this condition is tracheobronchitis which describes the infection in the windpipe or trachea and bronchial tubes. Tracheobronchitis is a multi-factorial disease which can be caused by several different viruses as well as bacteria which cause a specific hacking cough often described as a “honk.”

Testing for dog influenza is available, but it can take two to three weeks to definitively diagnose. Treatment needs to be initiated prior to definitive diagnoses. Generally, treatment consists primarily of supportive care in the form of fluids to maintain hydration and other medications to keep your dog comfortable. Antibiotics may be used to treat secondary bacterial infections.

Prevention of exposure to sick dogs is ideal. It is advisable to keep your dog away from any sick dogs and limit their exposure to dogs at dog parks and other public places. However, since some dogs with the flu don’t show any symptoms, this isn’t always possible.

Therefore, prevention of dog flu is best achieved by having your dog vaccinated against the Influenza A viruses (H3N8 and H3N2). The vaccination is given as an initial inoculation and then a booster within three to four weeks. After the initial series, the vaccine is given once a year.

However, if your dog is showing any signs of illness, contact your veterinarian as soon as possible to ensure your dog lives a long, healthy and happy life.

Jeff Castle is a veterinarian at Clark County Veterinary Clinic.