On May 18, the University of Pennsylvania’s New Bolton Center confirmed one of its equine patients tested positive for equine herpesvirus myeloencephalopathy. EHM is the neurologic form of EHV-1.
The horse, who exhibited neurologic signs, was at the university’s Moran Facility in Kennett Square. This is a critical care center designed to prevent infectious disease spread between patients. The horse remains isolated in quarantine, and no other cases have been identified.
Pennsylvania Department of Agriculture officials stated the potential for exposure to other equine patients at New Bolton Center to be extremely unlikely. Therefore, the large animal hospital remains open and fully functional.
Herpesvirus is highly contagious among horses. It can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and 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 include cough, decreased appetite, depression, and a nasal discharge. Pregnant mares typically show no signs of infection before they abort. Abortions usually occur late in gestation (around eight months) but can be earlier. They can occur anywhere from two weeks to several months following infection with EHV-1.
Horses with 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 is easily spread by nose-to-nose or close contact with an infectious horse. These includes sharing contaminated equipment including bits, buckets and towels; or clothing, hands, or equipment of people who have recently had contact with an infectious horse. Routine biosecurity measures, including hygiene and basic cleaning and disinfection practices, should be in place at all times 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 disease control is disease prevention.