Cornell Equine Herpesvirus Update

New information has surfaced in regards to the voluntary quarantine at Cornell University's equine hospital due to two cases of the neurologic form of equine herpesvirus (EHV-1). New York State Department of Agriculture and Markets' (NYSDAM) animal health officials, along with veterinarians from the equine hospital, are investigating the two confirmed cases. Both cases of EHV-1 involved patients of the equine hospital at Cornell University and could have potentially exposed 69 other horses to the disease.

EHV-1 is a highly contagious virus that can cause a variety of ailments in horses including rhinopneumonitis (a respiratory disease mostly of young horses), abortion in broodmares, and myeloencephalopathy (the neurologic form).

New York State Veterinarian David Smith, DVM, said, "While a common virus in horses, we are taking this situation very seriously given the large number of horses that have potentially been exposed to a highly communicable and sometimes fatal disease. To date, no other horses have showed signs, nor tested positive for the virus. However, this serves as an excellent reminder to horse owners that they should always be cautious of introducing new horses with an unknown disease status."

"We recognize the seriousness of the equine herpesvirus type 1 and other infectious diseases," said Alfonso Torres, DVM, MS, PhD, associate dean of public policy at the New York State College of Veterinary Medicine at Cornell University. "Thanks to our surveillance systems and access to highly sensitive testing at the New York State Veterinary Diagnostic Laboratory, we were able to rapidly identify the infectious agent and implement appropriate actions immediately to prevent the spread of the infection."

One of the two confirmed EHV-1 cases involved a 1-day-old foal that was admitted to the equine hospital on March 18. The foal died two days later of pneumonia, and tests revealed the presence of EHV-1 on March 25. During the same time a gelding was being treated at the hospital for a spinal injury. He was discharged on March 22, but became severely ill and showed neurologic clinical signs after arriving back at his home farm. This horse tested positive for EHV-1 on March 30. The gelding is now recovering.

In response to the two confirmed cases, both the gelding's farm and the equine hospital were quarantined immediately, restricting movement and access to animals at both facilities. Horses at both facilities are being monitored closely and veterinarians are taking their temperatures twice daily. So far, no animals have exhibited a fever attributable to EHV-1, which would be an early indication of the virus. At the hospital, polymerase chain reaction (PCR) tests also have been completed for four consecutive days on all current patients. The PCR samples from all animals in the hospital are negative, indicating that no virus shedding is occurring.

As part of this ongoing investigation, NYSDAM is working to determine the infection source, as well as to identify and isolate potentially exposed horses. In doing so, Cornell has been contacting all referring veterinarians and the owners of 69 other equine patients that might have been exposed while at the equine hospital. NYSDAM also is communicating with private veterinarians to provide information related to this situation and is prepared to follow up on possible quarantines of trace-out barns of the 69 potentially exposed horses, if necessary. At this time, neither NYSDAM nor Cornell know of any other animals that have showed signs or tested positive for EHV-1 in association with this incident.

Out of an abundance of caution, the quarantine at the hospital will remain in effect through April 11.

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