California EHV-1 Causing EHM Disease Update as of 12 pm 5/21/2011
California has one new confirmed case of Equine Herpes Myeloencephalopathy (EHM) caused by EHV-1. There are 16 confirmed EHM cases in the state.
The positive confirmed cases are located in the following 11 counties: Amador(1), Glenn(2), Kern(2), Los Angeles(1), Marin(1), Napa(1), Placer (2), Plumas(1), Shasta(1), Stanislaus(3), Ventura(1).
Fifteen(15) of the confirmed positive EHM CA cases participated in the National Cutting Horse Association’s Western National Championships in Ogden, Utah.
One(1) of the confirmed positive EHM CA cases participated only in the Kern County Cutting Horse Event on May 13th in Bakersfield, CA.
One confirmed positive EHM horse was euthanized after showing severe neurological signs associated with EHM.
Two confirmed positive EHM horses are being treated at the University of California Veterinary Medical Teaching Hospital in Davis.
Six positive horses have displayed neurological signs. The other cases have only been febrile.
All positive confirmed EHM cases are under a State Quarantine.
A suspect case of Equine Herpes Myeloencephalopathy (EHM) was investigated by Animal Health Branch veterinarians. This mare did not participate in the National Cutting Horse Association’s Western National championships in Ogden, Utah from April 30 – May 8, 2011, nor did she participate in the Kern County Cutting Horse Event on May 13th. This mare did participate in the Rancheros Vistadores ride in Santa Ynez, CA from May 5 – 12, 2011. This mare is exhibiting neurological signs compatible with a number of equine diseases or conditions. Three sets of nasal swabs and blood testing on this mare indicate she is negative for the mutant strain of EHV-1 that causes EHM and she is positive for the common strain of EHV-1 that most commonly causes respiratory signs but may also cause neurological signs in a low percentage of these cases. These findings indicate this mare is not associated with the ongoing EHM outbreak. 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.
