Two More Remington Park Horses Test Positive for EHV-1

On Nov. 21 the Oklahoma Department of Agriculture (ODA) updated the status of Remington Park racetrack in Oklahoma County following the initial confirmation of a horse there testing positive for equine herpesvirus-1 (EHV-1). Two additional horses have tested positive: one in the index case’s barn, and one in another barn where 100 more horses were exposed.

Both new cases were positive on polymerase chain reaction (PCR) testing, although both were clinically normal and without fever. The new barn has also been quarantined.

The New Mexico State Racing Commission reported in a statement that entry is being barred for horses from Remington Park until further notice.

EHV 101

Herpesvirus is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and equine herpesvirus myeloencephalitis (EHM).

In many horses the first or only sign of EHV-1 infection is fever, which can go undetected. In addition to fever, other common signs of EHV-1 infection in young horses include cough, decreased appetite, depression, and a nasal discharge. Pregnant mares typically show no signs of infection before they abort, and abortions usually occur late in gestation (around eight months) but can be earlier. Abortions can occur anywhere from two weeks to several months following EHV-1 infection.

Horses with the neurologic form (EHM) usually have a fever at the onset of the disease and might show signs of a respiratory infection. A few days later, neurologic signs such as ataxia (incoordination), weakness or paralysis of the fore- and hind limbs, urine retention and dribbling, loss of tail tone, and recumbency (inability to rise) develop.

Herpesvirus spreads easily via nose-to-nose or close contact with an infectious horse; sharing contaminated equipment including bits, buckets, and towels; or by way of clothing, hands, or equipment of people who have recently had contact with an infectious horse. Establish and maintain routine biosecurity measures, including hygiene and basic cleaning and disinfection practices, to help prevent disease spread.

Current EHV-1 vaccines might reduce viral shedding but are not protective against the neurologic form of the disease. Implementing routine biosecurity practices is the best way to minimize viral spread, and the best method of controlling the disease is preventing it.