Equine Herpes Myeloencephalopathy in 10 California Horses; Ramona Rodeo Reports No Problems

A highly contagious virus that causes neurological problems in equines has been found across the country, including 10 cases in California, causing the euthanizing of one horse in the state and cancellation of some U.S. equine events. However, Ramona Rodeo organizer Joani Georgeson has told Ramona Patch that she doesn't expect a problem here, though she is monitoring the situation carefully.

"We have to post signs that say no water source sharing but, as of right now, we are OK," Georgeson said Wednesday morning. "We have been keeping up with it through our California veterinarians. I know it has hit Northern California really hard."

Georgeson said no one has dropped out of this weekend's Ramona Rodeo because of any problem. The event runs Friday through Sunday at Fred Grand Arena.

Equine Herpes Myeloencephalopathy (EHM) caused by Equine Herpes Virus (EHV-1) has been confirmed in 10 horses in California, according to a news release from the state Department of Food and Agriculture (CDFA). One horse has been euthanized after showing severe neurological signs often associated with the disease. To follow updates on this disease in California, click here to go to the CDFA alert page.

All of the infected horses recently attended the National Cutting Horse
Association’s Western National Championships in Odgen, UT, on April
30-May 8, where they were most likely exposed to the virus, according to the CDFA release. As of Wednesday morning, there is no outbreak reported that has spread among any horses that did not got to this event.

All California horses that have been in contact with an infected horse and show signs of disease or test positive for EHM will be placed under a CDFA quarantine to limit spread. The outbreak is evolving and CDFA will continue to investigate cases and provide updated information.

The department has contacted all 54 exhibitors from California who participated in the Utah event and asked them to isolate and monitor their horses for clinical signs of EHV-1. A rectal temperature in excess of 102ºF commonly precedes other clinical signs. Therefore, horse owners with potentially exposed horses are urged to take temperatures on each horse twice a day. If a temperature above 102ºF is detected, the horse’s private veterinarian should be contacted immediately for evaluation
and laboratory testing of the animal.

Equine Herpes Virus may spread quickly among horse populations. It is not transmissible to humans. Horse-to-horse contact, aerosol transmission, and contaminated hands, equipment, tack and feed all play a role in disease spread. 

Horses infected with the neurological strain of EHV-1 may show any of the
following clinical signs: nasal discharge, lack of coordination, hind-end weakness, lethargy, urine dribbling and diminished tail tone. There is no specific treatment for EHM. Treatment may include intravenous fluids, anti-inflammatory drugs and other appropriate supportive treatment. 

Immediate separation and isolation of equines and implementation of appropriate biosecurity measures are key elements for disease control, according to the CDFA news release. Currently, there is no equine vaccine that has a label claim for protection against the neurological strain of this virus.