New Dog Flu Spreads in U.S., But Death Rate Is Low

Maryann Mott
for National Geographic News

September 27, 2005

A new, highly contagious respiratory virus thought to affect only the greyhound racing industry is now being detected in family dogs.

Canine influenza, a sometimes deadly disease, has struck pet dogs in New York, Florida, and Massachusetts, researchers said at a press conference held yesterday by the Centers for Disease Control and Prevention (CDC).

Edward Dubovi at Cornell University's Animal Health Diagnostic Center in Ithaca, New York, said serum samples from a number of suspected outbreak cases are arriving at his laboratory for testing.

He says he should know by the end of this week if the virus has infected more pets in other states.

Jumping Species

Canine flu was first discovered last year after an unusual illness began to appear at greyhound racetracks in Florida.

Cornell virologists, working with researchers at the CDC and the University of Florida, determined the sick greyhounds had a type of influenza ordinarily found only in horses.

This finding is the first scientific report of an equine influenza virus jumping the species barrier, and researchers are unsure how it occurred.

Virtually 100 percent of exposed dogs become infected, the researchers said. The virus is spread from dog to dog via coughing, contaminated objects, and even people.

Nearly 80 percent of dogs exposed to the virus contract only a mild form of the disease, which mimics kennel cough—a type of canine bronchitis that is rarely serious.

Canine influenza symptoms include low-grade fever, cough, and nasal discharge.

Nearly 20 percent of infected animals do not display any clinical signs but can still spread the disease.

The mortality rate is around 5 to 8 percent, says veterinarian Cynda Crawford at the University of Florida's College of Veterinary Medicine in Gainesville.

"I want to stress that despite the rumors that are out on the Internet and other such sources, this disease is not as deadly as people want to make it," Crawford said. She says she receives more than 30 calls a day from concerned veterinarians.

Sick Pets

Evidence of canine influenza in pet dogs was first discovered in April, although Crawford says it's unclear which population—pets or racing greyhounds—the virus actually hit first.

The flu is now showing up in Florida animal shelters, boarding facilities, and veterinary clinics, mostly in Broward, Dade, and Palm Beach counties.

Florida Agriculture and Consumer Services Commissioner Charles H. Bronson alerted the public last week to the canine respiratory disease.

Many Hurricane Katrina evacuees, accompanied by their pets, are temporarily relocating to the state. Bronson believes that the influx of new arrivals could increase the number of infected animals in coming weeks.

The bordetella vaccine, which protects dogs against kennel cough, does not work against the flu, Crawford said. Development of a vaccine for canine flu is currently underway.

In the meantime, Nina Morano of the CDC said owners should take common sense precautions to protect their pooches from the virus:

• If your dog exhibits any signs of respiratory illness, immediately see your veterinarian. Tell the doctor if your dog recently boarded at a kennel.

• Use a boarding kennel you are familiar with.

• Stay on the lookout for announcements of disease outbreaks in your area.

"It's a time to be very watchful and take a reasonable approach, but certainly not to panic," Morano said.

The American Boarding Kennels Association says it knows of only one facility in New York that was hit by the virus earlier this month.

Pets and Public Health

Dubovi, the Cornell veterinarian, hopes the attention raised by the new dog flu virus will help address a fundamental research problem related to animals and public health.

"As populations get denser and domestic animals mix with each other and with wildlife, we have to be aware that disease-causing agents can jump species," he said in a written statement.

"Therefore, the way public health officials monitor the transmission of disease from one species to another must be reexamined closely."

Dubovi sees the need for a surveillance system to quickly identify unusual pathogens in pets.

More than 75 percent of all infectious diseases that have emerged in the last 50 years have come from animals, veterinary experts say.

No cases of humans contracting canine influenza have been reported so far, Dubovi says.

He and his colleagues plan to keep a close watch, though, for any signs that the virus may be harmful to humans.

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