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EHV-1 Alert

hm-outbreak-featureThere have been 7 recent cases of Equine Herpesvirus Myeloencephalopathy that have been confirmed in California. Four of the cases participated in a horse show in Las Vegas, NV on October 24-29, 2016.

EHV-1 can cause four manifestations of disease in horses, including neurological form, respiratory disease, abortion and neonatal death. 

It is important to learn the signs of this virus, and to take precautions to protect your horses.

Signs of EHV-1:  fever, nasal discharge, hind end weakness, diminished tail tone, lethargy, urine dribbling, head tilt, leaning against a fence or wall to maintain balance, and inability to rise.

According to the American Association of Equine Practitioners (AAEP), after infection, the incubation period may be as short as 24 hours, but is typically 4-6 days, and can be longer. EHV-1 typically causes a two-phase fever peaking on day 1 or 2 and again on day 6 or 7. With respiratory infections there is often serous or mucoid nasal and ocular discharge, but not a lot of coughing. There may be some persistent enlargement of lymph nodes under the jaw. With the neurologic form there are typically minimal respiratory signs, with fever (rectal temperature greater than 102 degrees F) being the only warning sign. Neurologic disease appears suddenly and is usually rapidly progressing, reaching its peak intensity within 24 to 48 hours from onset of neurologic signs.

Your horse has been exposed if it has been in close contact with a confirmed case of the Equine Herpes Virus (EHV-1) within the last 14 days.


November 15, 2016 Update

There were no new clinical EHV-1 horses moved to quarantined isolation today at the LAEC (Los Angeles Equestrian Center). Currently, quarantined isolation is home to twelve (12) horses. To date, there have been seven confirmed cases of Equine Herpesvirus – 1 Myeloencephalopathy (EHM), one of which was euthanized due to the severity of the disease. The six neurologic cases and four confirmed EHV-1 positive horses continue to show improvement and remain in isolation. In addition, two febrile horses in isolation have twice tested negative and will continue to be monitored in isolation.

Enhanced biosecurity measures are in place in all barns under quarantine and all horses’ temperatures are monitored twice daily. CDFA veterinarians, livestock inspectors and USDA animal health technicians continue to monitor the quarantine and incident situation on-site and will provide additional updates as they become available.

Recommendations for Participants at Equine Events

CDFA reminds horse owners traveling with horses to participate in an equine event, that there is always disease risk when horses of unknown health status are commingled for a show or competition.  CDFA strongly recommends that horse owners practice proper biosecurity when attending an equine event.  Compliance with basic biosecurity practices is an important factor in reducing risk of exposure to all contagious equine diseases.  Basic biosecurity measures to decrease potential disease spread at equine events include:

  • Limit horse-to-horse contact.
  • Limit horse-to-human-to-horse contact.
  • Avoid use of communal water sources.
  • Avoid sharing of equipment unless thoroughly cleaned and disinfected between uses.
  • Monitor your horse for clinical signs of disease and report any temperature over 102°F to a veterinarian.

Don’t forget to vaccinate against this disease! All USEF shows require proof of vaccination against EHV in the last 6 months prior to any show. Give our office a call at (916) 687-6870 to schedule a vaccine appointment to make sure your horses are protected!

For more information, visit the following sites:

CDFA: http://www.cdfa.ca.gov/ahfss/animal_health/equine_herpes_virus.html
AAEP: http://www.aaep.org/info/horse-health?publication=753