Fears of dog flu epidemic spread as questions arise about vaccine's effectiveness

The outbreak of canine influenza that has sickened more than 1,000 dogs in the Midwest has veterinarians across the country concerned that the virus will spread. Those worries intensified last week when tests performed at the University of Wisconsin-Madison and Cornell University confirmed that the illness is being caused by the H3N2 flu strain.

Keith Poulsen

Problem is, commercially available vaccines--the most well known of which is Merck ($MRK) Animal Health's Nobivac--protect against a different strain, H3N8, which has been prevalent in the U.S. for the last 10 years. "It's believed that the H3N2 strain was introduced here from Asia, but how it happened is not known," said Keith Poulsen, clinical assistant professor at the University of Wisconsin School of Veterinary Medicine, in a press release.

As for the effectiveness of the existing vaccine, that's "unknown at this time, but it is likely to be less effective," Poulsen added. That said, he recommended that dog owners in the areas where the disease has been detected get the vaccine, because it could reduce the severity of the flu.

John DeVries, assistant director of the Oradell Animal Hospital in Paramus, NJ, is one of many veterinarians expressing concerns this new strain of dog flu could spread across the country. He told the local paper, The Record, that a similar outbreak occurred 10 years ago but was not nearly as worrisome. "The difference with this outbreak is it's a strain we have never seen here before in the United States. It seems to be more potent," he told The Record.

Dog flu can be particularly dangerous to pets under age 1 and over age 7. It has been tied to 5 deaths in the Midwest so far. And unlike the older strain, H3N2 can spread to cats--a potential problem because there is no feline flu vaccine, Poulsen said.

Neither strain of canine influenza is transmittable to people. Nor are they related to the pathogenic H5N2 avian flu that has been threatening poultry farms in the Midwest. Poulsen says little can be done to stop the spread, beyond giving dog owners advice that sounds a lot like what parents of young children are told every flu season: Dog owners should avoid close contact with other dogs, he says, wash their hands frequently, and call their pet's doctor if they see signs of the flu.

- here's the University of Wisconsin press release
- read more at The Record