Two horses in Jefferson County, Wisc., have been confirmed positive for equine herpesvirus-1 (EHV-1), according to a statement written by Scott Austin, DVM, Dipl. ACVIM, of the Wisconsin Equine Clinic, and released on the Wisconsin Horse Council Web site. Two horses, one of which tested negative for the virus, displayed neurologic signs and were euthanatized.

According to the statement, the cases are isolated to a single farm, which has been under voluntary quarantine since the first case was diagnosed via polymerase chain reaction (PCR) testing on blood and nasal swabs on Jan. 22.

From Austin’s statement, the subsequent cases developed as follows:

“On Jan. 23, the EHV-1 was confirmed as the neurotropic form of the virus. All resident horses were tested for EHV-1 by PCR testing of a nasal swab and blood. On the day of testing, three horses were identified as having fevers (horses B, C, & D). No horses were positive on nasal swabs for EHV-1 and one horse was positive on the blood test (Horse B).

The current status of horses on the property is as follows:

Horse A: index case, confirmed positive for neurotropic EHV-1. He developed rear limb paralysis and went down. This horse was euthanatized four days after the diagnosis was made.

Horse B: Fever and positive PCR on blood. Fever has resolved and no other clinical signs have been seen.

Horse C: Fever and negative PCR on blood and nasal swab. This horse developed rear limb ataxia and bladder paralysis on Day 3 after testing. He became recumbent within 12 hours and was euthanatized. A PCR on his blood at the time of euthanasia was still negative for virus. Results of post-mortem examination are still pending.

Horse D: Fever and negative PCR on blood and nasal swab. The fever resolved within 36 hours and no clinical signs of respiratory or neurological disease have been seen.

The voluntary quarantine on the farm remains in effect. No new febrile horses or clinical signs of respiratory or neurological disease have been identified since Jan. 27, 2007.”

For more information on EHV-1, check out our free PDF library of EHV-related articles including images, or all our archived EHV-1 articles on TheHorse.com.