Dr. Cynda Crawford, an immunologist at the University of Florida's College of Veterinary Medicine, said in an audio interview posted on the university Web site that the disease is only deadly in rare cases — about 10 percent in puppies and old dogs — but is of concern because it is spreading rapidly.

It is believed that the new virus may have mutated from an equine influenza strain, she said.

Like most flu viruses, it can be spread by air, as well as by contact, and the populations of dogs most at risk are those in shelters, kennels, boarding operations or other situations where a lot of dogs are housed under one roof, she said.

The disease could also spread in parks where pet owners let their dogs off the leash to socialize, vets say. Dog parks are a perfect playground for contagious diseases because when animals share toys and water dishes, they also are sharing germs.

The symptoms of the disease include coughing and sneezing, and there is concern that it could be spread in vet waiting rooms, Crawford said.

"When you bring a bunch of dogs together under one roof, if a dog happens to be infected, then the virus will spread rapidly," she said. She compared the situation to what happens with young children in school.

As yet, there is no test for the flu that vets can administer, she said.

The virus is too new for any dogs to have developed immunity to it, so pet owners should watch their dogs carefully for any symptoms.

"The concern is that the dog population on the North American continent is wholly 100 percent susceptible," Crawford said.

Seattle veterinarian Dr. Kenneth McKim recently treated some dogs with "kennel cough," but said the new virus is different.

The Virology Lab at Cornell University in New York isolated the first influenza virus from a dog that died during one of the racetrack outbreaks. Non-greyhounds have also been found to be infected by this influenza virus.

The canine influenza virus is a virus that originally infected horses. It is identified as the H3N8 virus, and has been in the horse population for at least 40 years.

Signs: Since this is a new virus to cause disease in dogs, all dogs are potentially susceptible to infection. As with any disease, there is variability in the clinical signs and the eventual outcome of the infection. The most common sign is a cough that can persist for up to three weeks regardless of treatment. Dogs may have a thick nasal discharge that seems to resolve with antibiotic treatment. This suggests that secondary bacterial infections may commonly occur. Dogs may also display sneezing and other respiratory signs. More severely affected dogs develop a high fever (104-106°F) with increased respiratory rates and other signs of pneumonia. There may be bleeding into the respiratory tract. Again, antibiotic therapy seems essential for recovery, since secondary bacterial infections are common. Some fatal cases of pneumonia have been reported, with the rate between 1 and 5%.

It may be difficult to differentiate a mild case of canine influenza virus infection from traditional infectious tracheobronchitis (kennel cough, which is caused by many different microbes) in an individual dog. It is more obvious when groups of dogs are affected. Since this is a new disease, virtually all dogs are susceptible to canine flu, regardless of age or vaccination history. Infection rates in kennels may reach 100% with clinical signs developing in 75-80% of dogs.

Boarding Precautions: Make sure the boarding facility you choose is clean and that the staff knows how to handle their boarders. Ask friends or colleagues what boarding facilities they recommend. Always stop by the facility prior to boarding your dog - if a facility does not allow or encourage this, be cautious.

If your boarding facility uses their own dishes, make sure they wash them thoroughly between each animal - a good boarding facility will already be doing this.

Why not have a special boarding kit set aside for these times? This kit could include:

Stainless steel dish set; Toys; comfortable pad, soft throw or bed; large baggie of dog's own food; baggie of dog's favorite treats; any medication your dog takes.

How this disease is spread: The incubation period (time from exposure to development of signs of disease) is relatively short, in the 2-5 day range. Most animals can transmit the virus for 10 or more days after the start of clinical signs. Nearly 20% of infected dogs will not display clinical signs and become the silent shedders and spreaders of the infection.

Canine influenza virus is spread by airborne respiratory secretions (e.g., from sneezing or coughing), contaminated inanimate objects, and even by people moving back and forth between infected and uninfected dogs. The virus is killed by routine disinfectants, such as a 10 percent bleach solution or a commercial disinfectant made for cleaning dog cages, kennels, runs, and more.

Management of symptoms by your veterinarian: Dogs with respiratory signs such as cough or sneezing should be tested for the presence of canine influenza. Antibiotics may be prescribed, as necessary, by the veterinarian. Symptomatic treatment may be necessary in some cases. In severe cases, intravenous fluids, supplemental oxygen, and other measures may be required.

Helping protect your dog from this disease: There is currently no vaccine available for this disease. Prevention is key. The disease is most likely to spread where large numbers of dogs come together, such as in boarding facilities, dog shows, dog classes, dog parks, etc. While the canine flu is not a cause for panic, owners should take precautions. This includes not allowing your dog to share toys or dishes with other dogs grouped together. Vaccinations for other diseases should be kept up to date to decrease the possibility of other respiratory diseases. Dogs diagnosed with respiratory infections should be kept isolated from other dogs for 2 weeks. Since the virus could be transmitted from dog to dog via human hands, clothing, and other items, persons should take precautions against inadvertently spreading the virus between dogs.

Always consult a veterinarian if you suspect your dog is sick, whether with dog flu or anything else. Some signs your dog may not be feeling his best include:

Higher than normal temperature. An adult dog's normal temperature ranges from 99.5 to 102.5°F. One way to monitor your pet is to use a thermometer to check temperature.

Not interested in food or treats; activity level decreased

Canine influenza virus is different than the avian influenza virus that causes bird flu. There is no evidence that canine influenza virus infects any domestic animals other than dogs.