An equine influenza outbreak among French sport horse farms could affect competing horses at the Fédération Equestre Internationale (FEI) Nations Cup 2012 show jumping event, held May 10-13 at La Baule, France, according to the French surveillance center for equine pathologies (RESPE) and the French governing body for equestrian sports (FFE). The French show jumping team has elected to pull its top four horses from the event in order to ensure their good health for the upcoming Olympic Games, the FFE reported.

Currently, no horses at the Nations Cup have presented any clinical signs of illness, said Christel Marcillaud-Pitel, DVM, RESPE director. Riders and veterinarians have taken precautionary measures to prevent disease spread at the event, including a full veterinary inspection of each horse prior to entering the stables and a verification of each horse’s body temperature twice daily, according to the FEI.

"The risk here is not just that these horses, which are all properly vaccinated, could become ill, but that they could carry the disease to other horses which are not vaccinated," said Marcillaud-Pitel. While the equine influenza vaccine protects horses by reducing the gravity of clinical signs or preventing them from developing signs altogether, it does not necessarily stop them from shedding the virus, she said.

Currently, three sport horse breeding and training farms, all within a 20-mile radius in Normandy’s Calvados region about three hours from La Baule, have been confirmed positive for the outbreak, according to Marcillaud-Pitel. In total, 210 horses are showing signs of fever and/or cough, including all 150 residing on one farm, 45 out of 70 at the second, and 15 out of 70 at the third, the RESPE reported. All horses had been vaccinated in all farms except young horses (under 2 years old)