11 states report flu virus that jumps from horses to dogs

A strain of flu virus that jumped from horses to dogs has caused sometimes deadly respiratory infections at dog tracks and kennels in at least 11 states and among some household pets as well, health officials reported Monday.

While cautioning dog owners to keep their pets away from other dogs if they have a respiratory infection to try to minimize further spread of the virus, experts said most dogs recover from the infection.

The discovery comes as public health officials are increasingly alarmed about a dangerous strain of flu that has been spreading among birds in Asia and occasionally infecting humans, but there is no evidence that the dog virus can spread to humans.

“We are going to monitor all cases of human exposure, but at this point there is no reason to panic,” said Ruben Donis of the federal Centers for Disease Control and Prevention in Atlanta. Donis noted that the virus has been known to cause the flu in horses for about 40 years without any reports of infecting humans. Tests also indicate it is sensitive to anti-viral drugs. The CDC held a news briefing to discuss the virus to coincide the release of a paper by the journal Science documenting the identification of the virus.

The discovery of the virus began with an outbreak of a mysterious respiratory infection among greyhounds at a racetrack in Florida in 2004.

Further analysis by CDC scientists determined that the dogs were infected with a strain of influenza virus nearly identical to one previously seen only in horses. Testing indicated the virus was probably responsible for a series of mysterious outbreaks of respiratory disease at six race tracks in Florida, Texas, Alabama, Arkansas, West Virginia and Kansas in 2004, and then at 20 tracks in Florida, Texas, Arkansas, Arizona, West Virginia, Kansas, Iowa, Colorado, Rhode Island and Massachusetts earlier this year, officials said.