Denton, County, Texas, EHV Quarantine Released

Denton, County, Texas, EHV Quarantine Released

In many horses, fever is the only sign of EHV-1 infection, which can go undetected.

Photo: Stephanie L. Church, Editor-in-Chief

On March 15 Texas Animal Health Commission (TAHC) officials released a quarantine put in place at a Denton County premises last month after a horse residing there tested positive for equine herpes myeloencephalopathy (EHM), the neurologic disease linked to equine herpesvirus-1 (EHV-1).

There are no other reported EHM cases in Texas.

The affected horse, a barrel racer, had shown signs of ataxia, loss of muscle coordination, and other neurologic signs consistent with EHM when evaluated by a local veterinarian. Prior to confirmation, the positive horse attended barrel racing events at the NRS Arena, in Decatur, Texas, on Feb. 15, and Northside Arena, in Fort Worth, Texas, on Feb. 14.

While the risk of exposure to the virus was low at the events, the TAHC encouraged owners of potentially exposed horses to take precautions.

The TAHC released the quarantine after more than 14 days of no new EHV-1 cases being detected and the previously positive horse tested negative for EHV-1.

Health Alert: Equine Herpesvirus

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 myeloencephalopathy (the neurologic form). In many horses, fever is the only sign of EHV-1 infection, 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 infection with EHV-1.

Horses with the neurologic form 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.

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