The affected horse, an unnamed and unraced filly trained by Jorge Abreu, was sent to Rood & Riddle Equine Hospital in Saratoga on Sunday, July 11, after exhibiting a fever. After being tested for a number of possible conditions, her EHV-1 test came back positive on Thursday afternoon, July 15. She is being treated by Luis Castro, DVM, and is improving.
Anthony Verderosa, DVM, director of NYRA’s veterinary department, is overseeing the quarantine, along with standard precautions and biosecurity protocols.
Barn 86 is home to 46 horses trained by Abreu and Kenny McPeek. All horses there will be monitored daily for fever and other clinical signs.
These horses will not be allowed to enter races or train among the general horse population during the initial quarantine period. Horses without clinical signs will have isolated training hours at the Oklahoma Training Track when training for the general horse population ends at 10 a.m.
According to a statement from NYRA, as of the evening of July 15, no other horses in Barn 86 have exhibited clinical signs.
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, the neurologic form).
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 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; 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.