On May 6, a 4-year-old Paint mare in Rogers County, Oklahoma, was euthanized after testing positive for equine herpesvirus-1 (EHV-1). The mare exhibited clinical signs such as hind limb weakness and urine retention starting May 2. Following her diagnosis, 10 horses that were exposed to her have been placed under quarantine to prevent further spread of the virus.

Equine herpesvirus is highly contagious and can lead to various health issues in horses, including respiratory diseases, abortions in pregnant mares, and neurologic manifestations known as equine herpes myeloencephalopathy (EHM). Initial symptoms often include fever, which may go unnoticed, along with respiratory signs like coughing and nasal discharge. Neurologic symptoms can develop days after the onset of fever, leading to severe complications.

Preventing the spread of EHV-1 relies heavily on biosecurity measures, including proper hygiene and disinfection of equipment and environments where horses are kept. While current vaccines may reduce viral shedding, they do not fully protect against the neurologic form of the disease. Therefore, maintaining strict biosecurity practices is essential for effective disease control and prevention.