The Idaho State Department of Agriculture has received confirmation that the equine herpes virus myeloencephalopathy (EHM) has been diagnosed in horses in Jerome, Gooding and Bannock counties. The three facilities where the horses were kept are all are privately-owned and now are under quarantine, officials said.
Horses that may have been exposed to EHV often take several days to demonstrate clinical illness and run the risk of shedding the virus undetected. Exposed horses that travel to shows or exhibitions could expose other horses before disease containment can be implemented, officials pointed out.
“At this time, the decision to cancel upcoming equine events and competitions remains with the event coordinators at each host facility. ISDA urges horse owners to avoid transporting their horses unless it’s absolutely necessary,” said ISDA spokeswoman Chanel Tewalt.
EHM is caused by a neuropathogenic strain of equine herpes virus (EHV-1) infection and results in neurological symptoms.
“One additional premises in Gem County also is under quarantine, due to a confirmed EHV abortion in a pregnant mare,” Tewalt said. “The EHV strain affecting the mare in Gem County was a non-neuropathogenic form, which is known to commonly cause respiratory disease -- as well as abortion -- in mares.”
An epidemiological investigation is underway one the four premises, but officials say there is no apparent connection between the cases.
EHV-1 is highly contagious among horses, but the virus poses no health threat to humans.
EHV-1 is present in the environment and found in most horse populations around the world. Horses are typically exposed to the virus at a young age, with no serious side effects, experts say.
Research has not yet determined conclusively why horses with EHV-1 can develop the neuropathogenic strain, EHM.
Symptoms frequently associated with EHM infection in horses include a fever greater than 101.5 degrees, incoordination, hindquarter weakness, lethargy, incontinence and diminished tail tone. The virus is easily spread by airborne transmission, horse-to-horse contact and contact with nasal secretions on tack, feed and other surfaces. People can spread the virus to horses through contaminated hands, clothing, shoes and vehicles. There is no licensed equine vaccine to protect against EHM, Tewalt said.
“We encourage owners to contact their veterinarian immediately if they observe any symptoms of illness in their horses,” said Dr. Bill Barton, ISDA State Veterinarian.
EHM/EHV is a Notifiable Disease to the State Veterinarian in Idaho. Anyone suspecting or confirming a case of EHM/EHV should call (208) 332-8560 to report cases.
ISDA urges horse owners to incorporate preventative biosecurity measures while transporting or boarding horses at facilities with regular traffic on and off the grounds and especially where horses are likely to come in contact with new horses, such as at a racetrack, rodeo or fairgrounds.
Several preventative measures are important in minimizing a horse’s risk of contracting the virus. Horse
--Disinfect stalls before use,
--Never share water or feed buckets and tack or grooming equipment,
--Avoid unnecessary contact with other horses.
“Additionally, people who work at multiple equine facilities should practice biosecurity measures by washing hands and changing footwear and clothing before entering each facility,” Tewalt said.