Saturday, October 15, 2005

Dogs are normally resistant to most flu strains. Since about 2000, a new strain of dog flu has been spreading in America, and there’s no vaccine to prevent it.

To limit exposure to the flu, some dog owners are avoiding public places like dog shows and parks. Since the flu can spread where groups of dogs are housed, some dog owners are nervous about the practice of putting their pets in kennels. According to Edward Dubovil, director of the animal virology lab at Cornell University, 100% of dogs appear to be susceptible to infection by this new flu strain. It is estimated that 1-5% of infected dogs are dying from this flu strain. The symptoms of dog flu are akin to those of kennel cough, a more common and less serious illness.

Starting in 2004 there have been many outbreaks of flu at dog race tracks. Since early in 2004, researchers have been working to characterize the type of flu that is infecting dogs. In September of 2005 it was reported that this dog flu strain had crossed over from horses to dogs. This type of flu virus has been infecting horses for at least 40 years. It is expected that existing flu vaccines for horses can soon be adapted for use in dogs.

The spread of a horse flu virus to dogs is an example of what could happen with bird flu. Currently the bird flu is transmitted from birds to humans but does not spread easily from person to person. The new strain of dog flu shows signs of having been genetically modified from the original horse-preferring virus strain making it easy to transmit from dog to dog. Future genetic modifications of bird flu could better adapt it to humans and allow it to spread from person to person. The chance of such viral evolution can be reduced by limiting exposure of humans to bird flu.

At this time, the new dog flu virus strain does not seem to be a danger for humans. However, humans will be monitored for signs of infection by new genetic variants of the dog flu. Due to the close physical association between pet dogs and humans, a flu strain that could jump from dogs to humans would be of great concern. Recently evolved virus strains that jump from one species to another are often particularly lethal because the newly infected species may have little or no immunity to the new virus strain.