SACRAMENTO — The California Department of Food and Agriculture confirmed Sunday the list of California Equine Myeloencephalopathy (EHM) cases caused by the EHV-1 virus has grown to 17, including the first reported cases in Southern California.

All but one of the 17 confirmed cases participated in the National Cutting Horse Association’s Western National Championships April 29-May 8 in Ogden, Utah, according to the CDFA. The only EHM case not involving a horse that participated at the Utah cutting show was a horse that had participated in the subsequent May 13 cutting in Bakersfield at the Kern County Fairgrounds, the report said.

A mare that did not particpate in either of the cuttings yet exhibited signs of EHM was subject of an investigation by Anmal Health Branch veterinarians who determined she did not have the same strain of virus as the horses in the confirmed cases. The mare, a participant in the Rancheros Vistadores ride in Santa Ynez May 5 – 12, reportedly exhibited neurological signs compatible with a number of equine diseases or conditions, but three sets of nasal swabs and blood testing on this mare indicated she was negative for the mutant strain of EHV-1 that causes EHM. Instead, she tested positive for a more common strain of EHV-1 that most frequently causes respiratory signs and on rare occasion causes neurological signs.

“These findings indicate this mare is not associated with the ongoing EHM outbreak,” said the report. “This mare is quarantined, isolated and continues to receive intensive supportive treatment at the Veterinary Medical Teaching Hospital in Davis as the veterinarians continue consideration of other differential diagnoses.”

One confirmed positive EHM horse at the Bakersfield cutting was euthanized after showing severe neurological signs associated with EHM. Three confirmed positive EHM horses are being treated at the University of California Veterinary Medical Teaching Hospital in Davis. Seven positive horses have displayed neurological signs, and the other cases have only been febrile, the report said. All positive confirmed EHM cases are under a State Quarantine.

Last week, reports of the EHV-1 virus reaching California and other states from the Utah cutting kindled intense concern over a potential epidemic as government and veterinary agencies coordinated efforts to assess and manage the outbreak. To this point, positive confirmed cases are located in 11 counties, including Amador (1), Glenn (2), Kern (2), Los Angeles (1), Marin (1), Napa, (1), Placer (3), Plumas (1), Shasta (1), Stanislaus (3) and Ventura counties.

Horses that attended either the Ogden or Bakersfield cutting events are urged to undergo these “biosecurity recommendations”:
•Isolate exposed horse a minimum of 30 feet away from all other horses (round pen if necessary) for 21 days
•Monitor temperature twice a day for 14 days.
•Immediately report temperatures over 102F to your private veterinarian.
•Use separate equipment, bucket, halters/leads for isolated horse.
•Use protective clothing when handling isolated horse- coveralls, boot covers, gloves. Do not use same clothing with other horses
•Ideally, use separate personnel for isolated horses
•Restrict movement

The key to limiting disease spread, says the CDFA, is the is isolation of sick horses –sick horses are shedding virus and should be removed from exposing additional horses.

Share your insight into the EHV-1 situation in the e-Arena. Click here.