With a new, highly contagious canine flu spreading, dogs that are coughing should be kept at home for up to two weeks, a scientist who first described the illness said yesterday.

The scientist, Dr. Cynda Crawford, an immunologist at the University of Florida College of Veterinary Medicine and an author of a report on the canine influenza being released today by the journal Science, spoke at a news conference sponsored by the Centers for Disease Control and Prevention.

The C.D.C., which is tracking the disease, issued no official recommendations. But Dr. Crawford urged pet owners to continue to walk healthy dogs, visit dog runs, use boarding kennels and otherwise let animals congregate. But, Dr. Crawford added, owners should "use common sense," including isolating dogs with any symptoms of respiratory disease for up to two weeks and alerting a veterinarian's office before taking in a sick dog for treatment.

Dr. Crawford, who was joined at the news conference by scientists at the C.D.C. and the Cornell University College of Veterinary Medicine who are studying the virus, said the flu seemed to kill 5 to 8 percent of the dogs it infected. But she emphasized that scientists did not "have all the answers" on fatality rates because the influenza strain was new and because it was hard to get accurate information about dog deaths. Last week, Dr. Crawford estimated the fatality rate at 1 to 10 percent. In the first outbreak she studied, at a greyhound track last year in Jacksonville, Fla., the flu killed about a third of the dogs with symptoms. But she said basing estimates on a single outbreak left "a false impression."

The flu initially mimics "kennel cough," a common disease usually caused by Bordetella bronchiseptica, a bacterium related to the one that causes whooping cough in children. About 80 percent of infected dogs develop a cough, nasal discharge and possibly a fever; a smaller number go on to develop pneumonia. The 20 percent of dogs with no symptoms are presumed to be contagious, Dr. Crawford said.

Dr. Ruben Donis, chief of molecular genetics for the influenza branch of the disease control agency, said the flu had jumped from horses to dogs, "a very rare event of considerable scientific interest." But, Dr. Donis said, "at this point, there is no reason to panic."

Although there has been speculation that the influenza could now jump to humans because dogs live more intimately with them than horses do, the H3N8 strain has been found in horses for over 40 years without ever causing a documented human case, he said. A vaccine for the canine flu is under development, he said; a vaccine for the equine version already exists.

It is unclear how widespread the disease is in pets around the country. The first outbreaks in kennels not connected to greyhound tracks were found in April, and cases among pets have been confirmed only in Florida, New York and Massachusetts. Dr. Edward J. Dubovi, chief virologist in Cornell's diagnostic laboratory in Ithaca, said he was testing samples from veterinarians in many states.