Canine influenza broke out in 2004. The doomsayers quickly predicted widespread epidemics with catastrophic losses. They were right in one way – the disease has indeed continued to pop up. But, outbreaks have remained small and few dogs have died.

Canine influenza is a highly contagious respiratory infection caused by the H3N8 influenza virus. It resembles the equine influenza virus so closely that researchers thought it may have mutated from the horse virus.

There are two clinical forms of influenza in dogs. Dogs afflicted with the mild form have a soft, moist cough that lasts for 10 to 30 days. It is often misdiagnosed as “kennel cough.”

The severe form is typified by a high fever and signs of pneumonia (a high respiratory rate and increased breathing effort). It has a fatality rate between five and eight per cent.

When canine influenza hit, dogs had no immunity to this new virus. Virtually every dog exposed became infected. About 80 per cent showed clinical signs. Thankfully, the mild form predominates and the severe form is rare.

Because influenza is caused by a virus and we don’t have virus-killing medications, there is no specific treatment. All we can do is support sick dogs. If they become dehydrated, we give them fluids. Antibiotics help control secondary bacterial infections.

Once the disease was recognized, researchers went on to confirm more infections. During the first five months of 2005, there were outbreaks at 20 Greyhound racing tracks in 11 states. What we now know, however, is that 2004 wasn’t the start of influenza infections. By analyzing stored blood samples for antibodies to the virus, outbreaks were tracked back to 1998.

The disease still continues to surface. As recently as June 2008, a new outbreak was discovered in Illinois, in pet dogs. A veterinarian became suspicious when he saw about 60 dogs with respiratory infections in just three weeks. Blood tests confirmed it was the virus.

As of June 2006, the virus had been reported in 25 states. Canada still seems free of the infection. A study in Ontario dogs up to the same date found just one dog (of 225 tested) with blood antibodies. The Greyhound that came up positive originated from a racing facility in Florida. So far, no clinical cases of canine influenza have been identified at veterinary laboratories in Canada.

Though cross-border transport of dogs is limited, it is possible for the virus to enter and take hold in Canada. We need to keep this in mind if there is an explosion of what is thought to be kennel cough in the dog population.