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29 cases confirmed in U.S. including 13 in CA


Local horse shows cancelled, state quarantines imposed to stop spread

May 19, 2011 (San Diego’s East County) – Horses from across the West were exposed to a deadly new form of Equine Herpes Virus at a Utah horse show. There is no vaccine for Equine Herpes Myeloencephalopathy (EHM), which is caused by Equine Herpes Virus (EHV-1). The disease, which results in neuorological symptoms, is highly contagious and often fatal. 


So far, the virus has not been reported in San Diego. But local horse experts are concerned—and horse owners are advised to take precautions.


“All of the infected horses recently attended the National Cutting Horse Association’s Western National Championships in Ogden, Utah on April 30 – May 8, 2011, where they were most likely exposed to the virus,” the California Department of Food and Agriculture warned in a May 17 press release. “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 in order to limit spread.”


“As people are becoming aware of this virus and the spread continues, I fully expect that San Diego horses will be affected,” stated an e-mail from PB&J farms sent to East County Magazine this evening. “Many local horse shows are being cancelled—just today the local Jamul horse shows were cancelled for 30 days and access to the local arena will be denied. There is no vaccine for the type of virus that is spreading and most affected horses will be euthanized.”

The disease is highly contagious among horses, though it can't be transmitted to humans, authorities indicate.  Horse owners are advised to avoid contact with horses from outside San Diego. In California, horses have tested positive in Amador, Glenn, Kern, Los Angeles, Napa, Placer, Plumas, and Stanislaus counties. Eight other states have also reported cases.

“Horses at the [Utah] event may have been exposed to this virus and subsequently spread the infection to other horses,” the East County Large Animal Practices warned in a press release issued today. “At this time control of the outbreak is critically dependent on biosecurity.” The veterinary experts advise against interstate transport of horses at this time.

Some states have shut down interstate transport of horses due to the disease outbreak. Others, including California, have imposed restrictions.

There are several forms of equine herpes viruses. Most common are the respiratory form and the abortive form, both of which have vaccines. However there is no licensed vaccine for EHM, the neurologic form.

Exposed horses should be isolated for 21 days and kept at least 30 feet away from all other horses and restrict movement. A rectal temperature should be monitored twice daily for 14 days and any temperature over 102 degrees F should be immediately reported to your veterinarian, who should order nasals swabs and blood tests.

Incubation period for EHV-1 is typically 2-10 days. In horses infected with the neurologic strain (EHM), symptoms may include nasal discharge, incoordination, hind end weaken ss, recumbency (lying down and unable to rise), lethargy, urin dribbling and diminished tail tone. Prognosis depends on severity of signs and the period of recumbency.


Handlers should use separate equipment, bucket, halters and leads for isolated horses. You should use protective clothing when handling isolated horses including coveralls, boot covers and gloves –and do not wear the same clothing around other horses. If possible, use separate personnel to care for the isolated animals.

Treatment may include IV fluids, anti-inflammatory drugs and other supportive care.

The U.S. Department of Agriculture is working in collaboration with state animal health officials across the nation to coordinate efforts, provide timely information and investigate the source of the outbreak. Practitioners are encouraged to report suspected or confirmed cases of EHV-1 and EHM to the State Animal Health Official.

“These efforts are essential to mitigating the health and economic implications of this current EHV-1 situation. Misinformation can often be an epidemic of itself,” concluded Jay Hickey, President of the American Horse Council, according to a press statement issued by the American Association of Equine Practitioners. “This latest disease incident only underscores the importance of implementing a pro-active national equine health program.”


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