Equine Herpes Myeloencephalopathy (EHM) case notification (PA case)

Update from the Pennsylvania Department of Agriculture, October 27, 2023

EHM case: On October 26 we were notified a case of EHM in a horse which was taken to a referral hospital late in the evening on October 25.  The horse subsequently tested positive for EHV1 on blood and swabs at the hospital.  PDA is conducting an epidemiological investigation and is calling owners of horses which may have been exposed to this horse at a high school rodeo in PA.  The rodeo dates were October 21 and 22, 2023, and the event was held in Armstrong County, PA.   EHM is included on the list of dangerous transmissible diseases in PA.

Due to the possible interaction between other horses at the rodeo and the positive horse,  PDA is currently contacting all rodeo participants. These potentially exposed horses will be quarantined to their premises for 21 days.  Temperatures will be checked twice daily during this time by the owner or caretaker, and they are instructed to keep a temperature log for each horse. Owners are instructed to contact their veterinarians if any horses have an increased temperature or show other clinical illness compatible with EHM, and also to report their concerns to the Department veterinarian on call (717-772-2852).  Compatible signs of illness include temperatures greater than 101.5 degrees Fahrenheit, nasal discharge, lethargy, depression, incoordination, hindlimb weakness, loss of tail tone, recumbency, inability to rise, leaning against solid structures to keep balance, and urine dribbling or inability to urinate.

If you examine an EHM suspect related to this case, please consult with the Department before submitting any samples for testing that includes EHV-1.  If approved to collect and submit samples, required samples will include nasal swabs and whole blood.  Collect the nasal swabs using polypropylene swabs (no cotton tipped swabs and no wooden handles). Place the swabs in a red top tube (no media). Keep samples cold. Submit immediately to the closest state lab and report to PDA at 717-772-2852 (preferred) or contact your regional office (see attached regional map with contact information).

It is not recommended that samples be collected from apparently healthy horses due to intermittent shedding of even apparently healthy animals.

Because EHV-1 is highly contagious, strict biosecurity practices are essential.  It is critical that they use unique equipment for each horse and avoid carrying virus on shoes or clothing. Equine Herpesvirus may be spread from horse to horse through direct contact or spread through aerosolized droplets.  Contaminated water, feed, tack, facilities, and transport vehicles can become contaminated with virus and be a source of spread.  Humans can spread the virus from horse to horse by contaminated hands, footwear, and clothing.  The rodeo participants are being provided with the following guidelines:

• Restrict human, pet and vehicle traffic in exposed-horse areas
• Limit direct horse-to-horse contact
• Limit stress to horses
• Eliminate sharing of equipment and personnel
• Clean and disinfect all equipment and shared areas where these horses may have been
• Use dedicated or clean footwear and use footwear disinfectant, hand sanitizer before handling each horse
• Handle any sick horse last
• Alert your veterinarian of the situation before they enter the premises

Biosecurity practices should become a part of every horse owner’s daily routine, and veterinarians should promote best biosecurity practices at every visit.

A disease fact sheet is attached and more information is available at Equine Herpesvirus Resources | AAEP.