Canine influenza is a flu virus, subtype H3N8, that causes respiratory infection in dogs. It is believed to have jumped species from horses and was first identified in an outbreak of respiratory illness in racing dogs in Florida in 2004.

According to the Centers for Disease Control, the first evidence of canine influenza in companion dogs was documented in spring 2005. Cases have been confirmed in numerous states, including two in Oregon in 2005; neither case was fatal.

Transmission

Canine influenza appears to be an airborne disease, much like kennel cough (Bordetella bronchiseptica). Physical contact between dogs does not seem to be required. Practically speaking, if your dog stays at home and rarely contacts other dogs, its risk of contracting the virus is likely low. If your dog is boarded or goes to day care or the dog park, it may be at a higher risk if the H3N8 virus is circulating in your area. Since 2005, no cases have been reported in Oregon. Humans, horses, cats and other animals cannot catch the H3N8 flu virus from dogs.

Symptoms

The symptoms of the canine influenza virus are similar to kennel cough; coughing is the most common symptom. Most dogs diagnosed with canine influenza experience a mild form of the disease. They usually suffer from a persistent cough that may last for as long as three weeks and may experience a yellowish nasal discharge that can be treated effectively with antibiotics.

Dogs who experience a more serious case of canine influenza frequently have a high fever and exhibit increased respiratory rates and other indications of bacterial pneumonia. Antibiotics treat this form of the disease successfully in about 95% of the cases. The fatality rate is estimated to be between 5 and 8%, but with early diagnosis and appropriate treatment by a veterinarian, this rate can be much lower.

Call your veterinarian if your dog develops a cough, especially if it has already received the Bordetella vaccine. If your dog is coughing, do not take it out to locations where it may infect other dogs. Be sure to tell your veterinarian if your dog has been boarded, sent to the groomer or involved in any social activities (dog park, day care, etc.) within the last month.

Remember, coughing can be indicative of a variety of significant diseases or conditions. Your veterinarian is best qualified to diagnose your dog.

Prevention

After handling a sick dog, wash your hands before touching your dog. Avoid contact with dogs that appear sick.

A canine influenza vaccine is now available. It requires two shots, given two to four weeks apart to dogs 6 weeks and older, and can be repeated annually. It is best to discuss your dog's specific risk factors with your veterinarian to determine whether vaccination against canine influenza is appropriate for your pet. If your dog goes to day care or if you plan to board your dog, you should check in advance to see if the vaccination is required. The Bordetella vaccine does not protect dogs against canine influenza.

In the Portland Metro area, a joint coalition of animal services organizations from Clackamas, Multnomah, and Washington counties, humane societies from Portland and southwest Washington, and the Oregon Department of Health have met to discuss admission and isolation procedures to reduce the spread of canine influenza in animal shelters in the Portland area. In August 2009, Multnomah County Animal Services announced it is testing selected dogs in its shelter to determine whether this virus has resurfaced in Oregon.