The flu’s gone to the dogs

October 13, 2009

Apparently pigs are not the only mammal kind enough to share their flu with others. Horses now have passed their own flu version, equine influenza, to man’s best friend.

The resulting canine influenza virus (CIV) is a new respiratory pathogen in dogs. This is another instance of mammal-to-mammal transmission of influenza-A viruses, which was previously thought to occur only between pigs and people.

Cynda Crawford, D.V.M., Maddie’s assistant professor of Shelter Medicine at the University of Florida, is co-discoverer of the canine influenza virus. Crawford led a group of collaborators from UF, Cornell University and the Centers for Disease Control in the first identification of the virus as a cause of respiratory infections in racing greyhounds in 2004. Subsequent determinations found that the virus was infecting dogs of all ages and breeds throughout the U.S.

The transfer and adaptation of the flu from one mammal host to another is a rare event. Although uncommon, jumping species is a trademark of the influenza virus, Crawford said.
She said canine influenza is also subject to mutation, but it would take years to undergo any mutation radical enough to adapt to humans.

Fortunately for dogs and their owners, a canine flu vaccine was released over the summer and is available nationwide. The UF College of Veterinary Medicine worked with pharmaceutical developer Intervet/Schering-Plough on a consultant basis to construct the vaccine.

“We need to decrease the infection and increase community immunity. Vaccination is the way to achieve both,” she said.
Crawford said working with people at other institutions to achieve a common goal is beneficial to everyone involved.

“When you work by yourself, you may get tunnel vision and become stagnated. Working with others can give you a more global picture and add to the complexity and completeness of your project by bringing the expertise of others to the table and getting new insights.”

Canine influenza is a community-acquired infection, so dogs housed in boarding kennels and shelters are most at risk. The vaccine is intended for these at-risk dogs, dogs that belong to healthcare providers and kennel staff, and dogs that travel to areas of the country where the virus is more prevalent.

So far 30 states and the District of Columbia have reported cases of canine influenza, with the virus most prevalent in New York, New Jersey, Pennsylvania, Colorado and South Florida. Recent outbreaks have occurred in northern Virginia, Connecticut and Atlanta.

There are 70 million dogs in the U.S., and with only a few thousand infected thus far, there are still many more dogs susceptible to CIV.

“Virtually every dog exposed will become infected,” Crawford said. “Fortunately, just like with people, the vast majority of dogs will recover without any complications.”