New Dog Flu Mimics Kennel Cough

The New York Times, Thursday, September 22, 2005
Highly Contagious Dog Flu Spreads

Donald G. McNeil Jr., Carin Rubenstein,

A new, highly contagious and sometimes deadly canine flu is spreading in kennels and dog tracks around the country, veterinarians said Wednesday.
The virus -- which scientists say mutated from an influenza strain that affects horses -- has killed racing greyhounds in seven states and has been found in shelters and pet shops in many places across the country, though the extent of its spread is unknown.

Dr. Cynda Crawford, an immunologist at the University of Florida's College of Veterinary Medicine who is studying the virus, said it spreads most easily where dogs are housed together, but it can also be passed on the street, in dog runs or even by a human transferring it from one dog to another. Kennel workers have carried the virus home with them, she said.

How many dogs die from the virus is unclear, but scientists said the fatality rate is more than 1 percent and could be as high as 10 percent among puppies and older dogs.

Crawford first began investigating greyhound deaths at a racetrack in Jacksonville, Fla., in January 2004, where eight of the 24 greyhounds who contracted the virus died.

"This is a newly emerging pathogen, and we have very little information to make predictions about it," she said. "But I think the fatality rate is between 1 and 10 percent."

She added that because dogs have no natural immunity to the virus, virtually every animal exposed will become infected. About 80 percent of dogs that are infected with the virus will develop some symptoms, Crawford said. She added that the symptoms are often mistaken for "kennel cough," a common canine illness that is caused by the Bordetella bronchiseptica bacteria.

Both diseases can cause coughing and gagging for up to three weeks, but dogs with canine flu may have fevers as high as 106 degrees and runny noses.

A few will develop pneumonia, which is sometimes fatal. Antibiotics and fluid cut the pneumonia fatality rate, she said. The virus is an H3N8 flu closely related to an equine flu strain. It is not related to typical human flus or to the H5N1 avian flu that has killed scores of people in Asia.

Experts said there are no known cases of the canine flu infecting humans.

"The risk of that is low, but we are keeping an eye on it," said Dr. Ruben Donis, chief of molecular genetics for the influenza branch of the Centers for Disease Control and Prevention, which is tracking the illness.

With the approach of the human flu season and fears about bird flu in Asia, there is much confusion among some dog owners who have heard of the disease.

Crawford said she was fielding calls from kennels and veterinarians across the country worried that they were having outbreaks.

"The hysteria out there is unbelievable, and the misinformation is incredible," said Dr. Ann E. Hohenhaus, chief of medicine at the Animal Medical Center in New York. She said she had heard of an alert from a Virginia dog club reporting rumors that 10,000 show dogs had died.

"We don't believe that's true," she said, adding that no dogs in her Manhattan hospital even had coughs.

Donis, of the CDC, said there is currently no vaccine for the canine flu. But he said one would be relatively easy to develop because a vaccine that prevents the related horse flu exists.

The canine flu is less lethal than parvovirus, which typically kills puppies but can be prevented by routine vaccination.

Laboratory tests, Donis said, have shown that the new flu is susceptible to the two most common anti-viral drugs, amantidine and Tamiflu, but those drugs are not licensed for use in dogs.

The flu has killed greyhounds at tracks in Florida, Massachusetts, Arizona, West Virginia, Wisconsin, Texas and Iowa. Tracks and kennels have been forced to shut down for weeks for disinfection.

In Chestnut Ridge, N.Y., about 88 dogs became sick by early September, about 15 percent of whom required hospitalization, according to Debra Bennetts, a spokeswoman for Best Friends Pet Care, a chain of boarding kennels. The kennel was vacated for decontamination by Sept. 17.

About 17 of the infected dogs were treated at the Oradell Animal Hospital in Paramus, N.J., where one died and two more were still hospitalized, according to a staff veterinarian.