The winter competition season is about to be underway. Every year we spend three months in South Florida to horse show. But with the recent equine herpesvirus cases, I’m wondering if we should reconsider?
The Equine Disease Communication Center has reported two confirmed cases of equine herpesvirus myeloencephalopathy, the neurologic strain of the infectious disease, in horses in Florida in December. The first was reported at the Tampa Bay Downs racetrack in a 2-year-old Thoroughbred filly on Dec. 10. Two barns at the track were under quarantine for 21 days as 74 horses were exposed. No new cases were reported, and the filly was treated at the University of Florida. The quarantine period was released at Tampa Bay Downs on Dec. 29.
On Dec. 23, another neurologic EHV-1 cases was reported in Palm Beach County at a private boarding facility. The EDCC report confirmed that 52 horses were exposed. The infected horse was treated at an isolation facility and the boarding farm is currently under quarantine, according to the University of Florida.
Both cases in Florida are not related to a larger outbreak of EHV that originated from Texas and spread through Western states earlier in the winter.
The equine herpesvirus is the broader name for a family of nine known strains of herpesviruses that affect horses. EHV-1 and EHV-4 are considered the most “clinically significant,” according to the University of Florida. Symptoms are mostly respiratory disease related, but nearly all horses are exposed to EHV-1 before they are two years of age.
After an initial infection, the virus can be “latent,” which means a horse can carry it without exhibiting symptoms until it is reactivated by stress, travel or strenuous exercise. The University of Florida estimates that 60% of horses carry latent EHV-1.
EHV-1 can cause respiratory illness symptoms but also abortion, foal death and sometimes neurologic disease. Routine vaccinations can reduce respiratory and reproductive disease symptoms, but does not protect against the neurologic form of the disease. Horses are diagnosed through a PCR nasal swab or blood test.
EHV-4 is often milder, with just upper respiratory infection symptoms like fever, nasal discharge and cough.
EHV-1 myeloencephalopathy or EHM happens when inflammation and small blood clots form in the vessels around the brain and spinal cord. It is considered rare, according to the University of Florida, with only 10% of infected horses progressing to EHM. These symptoms usually begin with a fever, lasting up to 10 days. Neurologic symptoms can appear around seven days and often progress rapidly. Other symptoms include incoordination and weakness, loss of tail bone, urine dribbling, head tilt and difficulty rising or the inability to stand.
Because EHV is a respiratory disease, it spreads easily from airborne particles. The disease can survive for a week on surfaces or in water, but is easily killed with disinfectants. The virus often spreads from direct nose-to-nose contact, on contaminated equipment, feed buckets, trailers, tack and even from hands and clothing.
As of Dec. 30, horse shows are continuing in Florida without increased risk of EHV infection. Horse owners and competitors are being asked to follow biosecurity measures, such as washing hands, equipment and buckets when working with multiple horses and avoid sharing feed and water buckets. Horses who travel should be isolated and quarantined for up to 21 days before being introduced to a new or returning to a herd or shared farm environment.
If you are concerned about your horses’ risk, you should speak with your veterinarian. You can also reach out to horse show and boarding barn management to find out what measures they’re taking to reduce risk.
The University of Florida offers more tips and information here. You can tune into our interview with Dr. Holly Helbig, an equine services veterinarian with Zoetis on Episode 143 of the Heels Down Happy Hour Podcast, who shared important biosecurity tips.
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