A recent outbreak of canine influenza in Virginia has brought the virus into the spotlight again. And with the swine flu in the news, and the human flu season coming on, veterinarians should be prepared to field questions about canine influenza to help clients differentiate among various forms of flu.

The canine influenza virus, H3N8, is highly contagious and spreads especially rapidly among dogs living in a confined space, such as a shelter or kennel. The virus was first identified in 2004 and is suspected to have originated as an equine virus, according to Colorado State University assistant professor of small animal medicine Kathy Lunn, BVMS, PhD, DACVIM.

Similar to other influenza viruses, H3N8 causes severe respiratory infection and cough. However, Lunn said that, unlike other influenza viruses, the canine flu has no season.

“It seems to be pretty much any month of the year that it can happen,” Lunn said. “It’s more related to dogs being kept in close proximity.”

Colorado is one of several “hot spots” around the country, although the virus has been detected in 30 states so far. Lunn and her colleagues are studying the best ways to diagnose the disease and are trying to determine how many dogs have been exposed to the virus.

“There is no perfect test, but the virus sheds very early in the course of the disease,” Lunn said.

According to the American Veterinary Medical Association (AVMA), almost every dog that is exposed to the virus becomes infected, but only 80 percent develop clinical signs. The signs are similar to kennel cough, and canine flu is frequently misdiagnosed as such.

Lunn said that if a coughing dog is brought in by a client within the first three days of a reported cough, a polymerase chain reaction (PCR) or antigen test can be used to detect the virus. However, after more than 10 days, a blood test for antibodies is a more effective diagnostic tool, she said.

Lunn said an outbreak is most likely to occur in a shelter or kennel type environment.

“If an outbreak happens in a shelter, the best way to control it is with isolation policies,” she said. “[Veterinarians] have to be ready to separate or use isolation to stop the spread.”

She added that it is also important to convey accurate information regarding the virus to clients and dog owners.

“It’s important that people know that it’s not the same as bird or swine flu and it’s not transmissible to people,” Lunn said.

However, people can carry it on their clothes or hands and infect other dogs, she said.

In June, Intervet/Schering-Plough Animal Health announced the availability of a vaccine for canine influenza. The vaccine is recommended for dogs at high risk for exposure to the virus, such as dogs in kennels or shelters where the virus is present. According to the AVMA, dogs that may benefit from vaccination include those that receive the Bordetella vaccine, since the risk groups are similar.

More about H3N8 canine influenza

• AVMA background information on H3N8
• 10 things to know about the H3N8 canine influenza
• Control of Canine Influenza in Dogs: Questions, Answers and Interim Guidelines from the AVMA
• CDC: Key Facts about Canine Influenza
• Canine Influenza Virus: Detection, Sampling and Statistics (Cornell University Veterinary Diagnostic Laboratory)