A newly emerging respiratory pathogen in dogs has been identified as a virus belonging to the influenza A family. These viruses can infect humans, domestic animals, (pigs, horses, chickens, ducks), and some wild birds. The University of Florida College of Veterinary Medicine has isolated and identified H3N8 influenza virus as the cause of a serious respiratory disease in dogs in shelters, humane societies, boarding facilities and veterinary hospitals in Florida. Cases have been predominantly in Dade, Palm Beach and Duval counties. Racing greyhounds in Florida have also been affected. There are confirmed cases in New York State. This particular strain is not known to affect humans or poultry and appears to be a mutated form of the equine influenza virus.

Influenza viruses are defined by membrane proteins that are distinguished by their genetic structures. These proteins are referred to as H and N. The H protein has 15 genetic subtypes and the N protein has 9 genetic subtypes. Very few of the subtypes have consistently circulated among people, (predominantly H1N1, H1N2, H2N2, H3N2), or domestic animals. Virtually all of the possible influenza subtypes exist among wild waterfowl. In birds the virus lives and is shed predominantly through fecal contamination. It is highly contagious among birds; waterfowl are usually asymptomatic but it can be deadly to domesticated birds, such as chickens. Reassortment of the virus commonly occurs when 2 different subtypes are present in the same animal. Influenza virus has the ability to change its molecular antigenic structure making previously immune animals susceptible.

This disease in dogs can mimic the kennel cough syndrome caused by Bordetella bronchieptica/parainfluenza virus complex. Since it is a newly emerging disease virtually 100% of exposed dogs will become infected. Dogs may remain asymptomatic, exhibit mild illness, or present with severe pneumonia. Approximately 20% of the dogs will be asymptomatic. The remaining 80% will develop clinical illness with the majority showing a mild syndrome that presents as a cough with or without a low grade fever. The cough does not respond to antibiotics or cough suppressants and generally lasts 10 to 21 days. The cough may be soft and moist or dry. A purulent nasal discharge may develop which is generally caused by secondary bacterial infection and is responsive to antibiotics. This presentation is difficult to differentiate from kennel cough syndrome. Standard treatments for upper respiratory infections should be instituted regardless of the cause.

The severe pneumonic syndrome presents as clinical pneumonia with high fevers (104 - 106), increased respiratory rate and difficulty breathing. Thoracic radiographs show generalized pneumonia with consolidation of the lung lobes. These dogs should be treated symptomatically with broad-spectrum antibiotics for secondary bacterial infections, hydration therapy, and other supportive care as needed. Mortality in these dogs is 1 - 5%.

No vaccine for canine influenza is currently available. The use of flu vaccines approved for other species is not recommended because of the potential for adverse and possibly fatal reactions.

Influenza virus is transmitted by aerosolized respiratory secretions, contaminated inanimate objects (food bowls, dog crates), and people moving from infected dogs to uninfected dogs. The virus is easily killed with any disinfectant that will kill parvovirus. The incubation period is 2 - 5 days and dogs can shed the virus for up to 10 days after the onset of symptoms. All dogs with symptoms of kennel cough or pneumonia should be isolated from other dogs for a minimum of 10 days after onset of symptoms to prevent spread.

There is no rapid test for canine influenza virus. Serology is available but antibodies do not develop until 7 or more days after the onset of symptoms. Convalescent samples 2 or more weeks after the onset of symptoms aid in the diagnosis. Positive serology testing only indicates that the dog was infected sometime previously, however a positive test gives veterinarians an indication that the influenza virus is in their community, so precautions can be taken with dogs presenting with "kennel cough". Early detection of virus in your community is important so that preventive measures may be instituted by careful handling of dogs with upper respiratory disease. Serum samples can be submitted to Cornell University Diagnostic Laboratory for testing for canine influenza virus. The cost is $20.00 per test and further information and submission forms may be found at:

http://www.diaglab.vet.cornell.edu/news.asp

Although canine influenza is not reportable in Illinois, the Illinois Department of Agriculture appreciates the voluntary reporting of laboratory confirmed cases of canine influenza in the state. This information will be shared with veterinary professionals in Illinois to alert them to the presence of the virus in the state. To-date there are no known reported cases of canine influenza in Illinois. Please contact the office of the State Veterinarian at 217-782-4944 to report cases. THE information requested includes the name of the veterinarian or clinic, city, county, the number of dogs affected, date of testing and test results.

MONDAY OCTOBER 3, 2005
By Peter Corner
Tribune science reporter
Epidemic of deadly flu in dogs seen as unlikely
A virus that sickened greyhounds at some racetracks is not a new strain of disease, and treatment is easy and effective, an expert says
Despite news reports warning that a new killer virus at dog tracks and animal shelters could move into the pet population, many experts say the "canine flu" may be an old and basically harmless disease.
"This virus has been circulating in the dog population for a long time, perhaps decades, and was unrecognized because it is so mild and so easily treatable," said Brad Fenwick, vice president for research and professor of infectious disease pathobiology at Virginia Polytechnic Institute.
Since last year, the canine flu virus has been implicated in dozens of dog deaths from respiratory disease at greyhound racetracks and kennels. Some facilities were forced to shut down for weeks to be disinfected. Rumors flashed on the Internet. Researchers were said to be rushing to come up with a workable vaccine.
But experts such as Fenwick, who specializes in medical problems of racing greyhounds, say a vaccine may not be needed. Although the virus can spread easily in the close quarters of tracks and shelters, it does not sicken many dogs. Those that do become ill usually recover with proper care.
"Half the dogs exposed to this virus never get sick," Fenwick said. "Of those that do, the majority will recover on their own. [Less than 1 percent] are at risk of getting a secondary bacterial infection that is easily treatable if they're given antibiotics."
"There is no killer dog flu crisis in greyhound racing, or outside it, for that matter," he said. "There's a lot of misinformation and a lot of unnecessary hysteria. Basically, it's a lot to do about very little."
In the Chicago area, there have been no confirmed cases of the virus, said Joanne L. Carlson, president of the Chicago
Veterinary Medical Association.
"Many news sources are citing this as an epidemic of a deadly virus, which it is not," she said.
The canine flu often causes "kennel cough," whose classic sign is a harsh cough that often prompts owners to think the dog has something caught in its throat. Kennel cough also can be caused by bacteria and other viruses, and a vaccine exists to prevent the bacterial version. Most animals recover from kennel cough with no treatment; others may require intravenous fluids and antibiotics to fight secondary infections. "There is a small number of fatalities, basically due to age or some other concurrent illness," Carlson said. "I think it's important not to panic, just to be aware of it arid watch for the main signs—coughing, gagging, a fever and nasal discharge. If your dog has them, consult your veterinarian."
The journal Science recently published a paper that identified the canine flu virus, finding that it is closely related to the horse influenza virus. Because that flu had crossed from horses to dogs, the paper raised the possibility that it perhaps could transmitted from dogs to humans. But the scientist who led the study attempted to reassure the public.
"We must keep in mind that this H3N8 equine influenza virus has been in horses for over 40 years. In all these years, we have never been able to document a single case of human infection," 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.
"That's not to say there isn't any risk ... but at this point there is no reason to panic."
Cases of canine flu first turned up last year in 22 racing greyhounds in Florida. Since then, scientists at the CDC, the University of Florida and Cornell University have found evidence of widespread infection in racing dogs at tracks across the country. The infection is believed to have spread because the dogs travel from track to track.
The researchers also tested 70 dogs of various breeds with respiratory diseases in Florida and New York pet shelters and veterinary clinics, of which 97 percent showed antibodies that indicated prior exposure. That finding cast doubt on whether the virus was really new.
Tests on stored blood Suggest the flu virus began infecting racing dogs between 1999 and 2003.
Fenwick was called in to consult by Dairyland Greyhound Park in Kenosha, Wis., which suspended racing for four weeks in April and May during an epidemic of kennel cough.
Bill Apgar, the track's general manager, said "about 950 dogs were involved and 80 percent showed some symptoms."
"But none of them died," he said. "Everybody did a really good job of handling it and it was contained at Dairyland. It never got outside."
Fenwick called the Kenosha track a good example of what's been happening at the tracks.
"No big deal: A zero mortality rate," he said. "It got recognized in greyhounds because we have such large numbers of them in certain locations, and veterinarians were called in to treat the dogs. Even a mild respiratory disease is of special concern to a canine athlete."
pgorner@tribune.com