Deadly Dog Flu Spreads

Aug. 18, 2009 -- Canine influenza, the potentially deadly H3N8 virus commonly known as dog flu, is spreading.

So far the virus has led to the death of one dog last week, closed down the kennel at Virginia's Fairfax County Animal Shelter, and, according to experts, is now affecting dogs in at least four other states: Colorado, New York, New Jersey, and Pennsylvania.

While the reason for the shelter outbreak, which killed a 15-year-old whippet owned by a clinical technician and sickened 26 dogs, remains unknown, it's possible that one or more infected dogs from Philadelphia or D.C. introduced the illness to Virginia.


"Dogs often move in and out of shelter systems over long distances, such as via breed and rescue groups," Edward Dubovi, director of the virology center at Cornell's Animal Health Diagnostic Laboratory, told Discovery News.

"Boarding kennels and even elite doggie day care centers can also result in cases, since, as for kennel cough spread, the virus is highly contagious and dogs may catch it from one another," added Dubovi.

He first isolated the canine influenza virus in 2004, after University of Florida researchers sent him fluid and tissue samples from greyhound race dogs that had died from a then mysterious respiratory illness at a Florida racetrack.

Dubovi and his team determined the cause was the H3N8 equine flu virus, which jumped from horses to dogs. In addition to spreading from dog to dog, canines can also catch it from humans, who may have come into contact with infected animals.

The illness has not yet sickened any people.

Symptoms in dogs can include fever, lethargy, loss of appetite and a respiratory infection that may last a few weeks. One to five percent of victims die from related hemorrhagic pneumonia.

Although 30 states have reported cases over the past five years, Dubovi said outbreaks are "usually sporadic and then die out."

"For example, we've seen outbreaks in San Diego, Los Angeles and Pittsburgh, but those all ended," he explained.

As officials work to contain the Virginia cases, nearby states and cities are also on guard.

Tara deNicolas, a spokesperson for the Washington Humane Society, told Discovery News, "No cases are currently in our shelter."

She added, "We're being very proactive, however, and are ordering tests whenever any possible symptoms surface."

Just last month, a vaccine was released for canine influenza. Dubovi said that, "in clinical trials, it reduces viral shedding and diminishes signs" of the illness. It's given in two doses, three weeks apart.

Dubovi would like to see "blanket vaccinations in affected areas, as it would be nice to get this virus out of the dog population."

The virus at present is more adapted to horses than to dogs, so wiping out the illness now would prevent future possible mutations within canines.

Since dogs are in regular contact with their owners and other people, the illness could potentially spread from dogs to humans in the future, he suggested, given that it has already jumped from one species of mammal to another.

More bad news appears to be on the horizon. Next month, Dubovi said he will announce the discovery of yet another new virus.

In the meantime, researchers continue to study why some viruses jump species, and what can be done to eradicate these illnesses.