State animal health officials confirmed April 10 that a horse in Lincoln County, South Dakota, has tested positive for equine herpesvirus-1 (EHV-1).
The horse developed neurologic signs, including incoordination and difficulty walking, and received treatment at a local veterinary clinic. Laboratory testing confirmed the disease.
The affected horse has traveled extensively in South Dakota for cutting and sorting events in the past few weeks.
State veterinarian Dustin Oedekoven, DVM, said EHV-1 is not uncommon in the horse population. It is highly contagious 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 myeloencephalopathy (the neurologic form). In many horses, the 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 infection with EHV-1.
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