Beware Of Dog Flu

When Victor Weil noticed that his food-loving Basset Hound lost his appetite, he knew something was amiss.

"He loves food more than anything," Weil told CBS News correspondent Mika Brzezinski about his 6-year-old dog, Weilson. "That's when I knew he was really sick."

Weil added that the dog suffered a constant cough and became very lethargic. "He just put his head on his paws," Weil said.

Weilson, it turns out, had contracted a highly contagious and sometimes deadly canine flu that is spreading around the country, Brzezinski reports.

On Monday, researchers reported that the mysterious disease was an influenza strain that jumped from horses to dogs.

Such a rapid jump into a new species is rare; the flu usually evolves into new strains more gradually.

But genetic tests of sick dogs found their disease almost identical to the H3N8 influenza strain that afflicts horses, scientists at the Centers for Disease Control and Prevention and University of Florida discovered. The results were published online Monday by the journal Science.

There is no evidence that it has spread to humans, or that it ever will. But at a Monday press conference, federal officials said they are monitoring the health of exposed dog owners — because a virus that jumps species once could do it again.

It was first detected at a Florida racetrack and several greyhounds died from it. Since then, it has shown up in dogs in eight other states and though the CDC says there is probably no risk of it infecting humans, they are tracking it closely, Brzezinski adds.

Weilson's doctor, Veterinarian Glenn Zeitz, says he's treated dozens of dogs suffering from this new virus. Symptoms are often mistaken for kennel cough — a common canine illness.

The difference is these dogs were much sicker. Many of these dogs were going on to pneumonia and had a high white blood cell count," Zeitz informs Brzezinski.

This new dog flu is being closely watched for another reason: Other viruses have jumped species, with tragic consequences. Avian flu, the West Nile virus and SARS all jumped from animals to humans.

So-called zoonotic diseases are a growing concern for the nation's disease sleuths.

"We have never been able to document a single case of human infection with this virus," said Ruben Donis, a researcher with the federal Centers for Disease Control and Prevention and principal author of the study.

"That's not to say there isn't any risk," said Donis, "but there is no reason to panic."

This new dog illness made headlines earlier this year as greyhound racetracks closed to control outbreaks. Veterinarians struggled to tell if the illness was a new variant of kennel cough or an entirely new disease.

The CDC researchers counted outbreaks at 14 greyhound tracks in six states from June to August 2004, and at 20 tracks in 11 states between January and May 2005.

While most attention has focused on racing dogs, the researchers tested 70 dogs of various breeds with respiratory disease in Florida and New York pet shelters and veterinary clinics. Some 97 percent showed antibodies to the new canine flu strain.

Tests of blood stored by racetracks suggests the new flu strain began infecting dogs sometime between 1999 and 2003, well before the first outbreaks were recognized, the researchers conclude.

The announcement follows months of rumors and growing worry among dog-lovers, fueled by unconfirmed Internet tales of massive dog die-offs. Influenza has never before occurred in dogs. It has been common in horses for more than 40 years.