Six horses at the Churchill Downs racetrack in Jefferson County, Kentucky, have tested positive for EHV-1. The horses reside on the backside of Barn 37, where 13 horses in total were tested. The original positive case remains hospitalized, while the additional five were immediately placed in secure isolation in Barn 42. The eight remaining horses in Barn 37 are being monitored multiple times per day for signs of illness.
An epidemiologic investigation identified Barns 36 and 38 as having increased risk due to potential indirect transmission from people caring for horses in Barn 37. Those barns have also been placed under quarantine. So far, there are no clinical cases in either barn. The Kentucky Department of Agriculture will continue to monitor these horses and will immediately test them if symptoms appear. These horses can qualify for release from quarantine by testing negative 14 days since last opportunity for exposure, or 28 days after last opportunity for direct exposure. The Kentucky Department of Agriculture identified November 30 as the date of last known indirect exposure.
As of December 2, Churchill Downs has modified its training hours to allow horses from Barns 36, 37 and 38 to access the track. The general population can train from 5:30-8:00 a.m. Horses from the three quarantined barns will have restricted access between 8:30-10:30 a.m. with a dedicated outrider pony. The positive horses in Barn 42 will not have access to the track.
Churchill Downs has implemented heightened biosecurity measures. It will lift exit restrictions on horses from unaffected barns as long as they have a valid Health Certificate within 24 hours of departure.
EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.
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 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 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.