University of Wisconsin scientists tracking a strain of influenza which has jumped from horses to dogs say it could potentially infect humans, though it is unlikely.

Equine influenza, an occasionally fatal flu virus that causes hemorrhagic (or "bloody") pneumonia, was first identified as a canine pathogen with the assistance of UW researchers, and now others at the university are trailing the virus across the state.

To identify the dog flu as equine influenza, UW public health professor and influenza researcher Christopher Olsen, in coordination with lead author Cynda Crawford of the University of Florida-Gainsville, and numerous other professors from other universities, helped draft a report linking the virus' genetic code to both species.

"This is a great example of interdisciplinary collaborative work to understand a new problem," Olsen said. "I think that the collaborative group of laboratories that went to work on understanding [the virus] is a good example of veterinary research working together in combating infectious viruses … that involve both animals and human beings."

In January 2004, the equine influenza virus first appeared in racing dogs at a track in Jacksonville, Fla., and has since spread to other tracks in Massachusets, West Virginia and Wisconsin, among other states.

The virus has also been found in domestic and kenneled dogs in New York and Florida.

Since the publishing of Crawford's report, UW researchers have been busy tracking the pathogen in Wisconsin.

Ronald Shultz of the School of Veterinary Medicine stands at the helm of UW's canine influenza research survey and has spent months observing dogs across Wisconsin for signs of the virus.

Schultz has found multiple traces of it in greyhounds at Dairyland Greyhound Park in Kenosha.

There have been no indications of the virus in domestic or kenneled dogs in the state yet, but Schultz said it is only a matter of time before cases begin cropping up outside of Dairyland.

"There is no question that this virus will move out into the dog population as a whole," Schultz said. "We are very concerned about the pet population because they are likely to see this virus."

Schultz added dogs in close proximity to other canines are most likely to contract the disease, but there is no known risk of the virus being transmitted to humans.

"We have no evidence to date to suggest it will jump from dogs into people," he said "At this point there's no reason to suggest a public health risk … but that's something that's hard to say with the little information we have on it."

Schultz added public health officials will be keeping a close eye on the matter.

"We don't know what the natural course of this is going to be," he said. "There is a possibility the virus will burn out."

But Shultz said he is less than optimistic about the virus' nature.

"More and more states are seeing the virus and it will eventually move its way across the country," he said.