EHV-1 Update

At the recent National Cutting Horse Association event in Odgen Utah, several horses contracted the EHV-1 virus.  Here is a current update from Pilchuck Veterinary Equine Hospital in Washington State confirming a positive tested patient.


by Pilchuck Veterinary Equine Hospital on Wednesday, May 18, 2011 at 10:50am


Press conference scheduled for Friday, May 20 at 11 a.m.

Snohomish, Wash., May 18, 2011Pilchuck Veterinary Hospital (PVH) is confirming that an equine patient has tested positive for equine herpesvirus 1 (EHV-1). The horse is being cared for in PVH’s equine isolation facility. This horse was shown at the National Cutting Horse Association event in Odgen, Utah, and developed a fever and neurologic signs after returning home to Eastern Washington.

According to Wendy Mollat, DVM, DACVIM, upon presentation to PVH, “the horse was immediately admitted to our designated equine isolation facility and has not been allowed direct or indirect contact with our general equine population. The horse is clinically stable and will remain hospitalized until confirmed to be no longer shedding the virus.”

Pilchuck Veterinary Hospital remains open for elective and emergency equine cases. Mollat emphasized that while the isolation facility at PVH is currently under quarantine, the general hospital is not under quarantine and remains open. The horse with EHV-1 is under maximal isolation with no contact with the general hospital population. All horses currently at the general hospital have tested negative for EHV-1. Due to the external cases in the horse community, high-level precautions are in place to prevent a positive horse from entering PVH.

It is also important to note that currently there is no evidence of EHV-1 disease spread outside the cutting horses that participated in the Odgen, Utah event. 

A press conference for media contacts will be held at PVH on this Friday, May 20, at 11 a.m., 11308 92nd Street Southeast, Snohomish (directions: Dr. Mollat will provide additional information and be available to answer questions.

  • If you would like to attend, email Charlotte Graeber at by Friday at 8 a.m.
  • If you are unable to attend, a summary will be available shortly after the conclusion of the press conference. Email Charlotte Graeber at to request.

Anyone with concerns about exposure of a horse should use the following guidelines and contact a veterinarian immediately: 

  • Segregate potentially exposed horses from any non-exposed horses by at least 50 feet. The exposed horse should not have direct contact with other horses for three weeks. Stall cleaning and husbandry practices should be separate for the potentially exposed horses.
  • Take your horse’s temperature rectally twice a day for 21 days from the time of exposure. If the temperature is over 102 degrees F, please contact a veterinarian immediately. A fever also generally precedes the development of clinical/neurological signs.
  • The preferred testing method is PCR analysis performed on a nasal swab and whole blood. This is only effective to identify horses that are actively shedding the virus.

As always, PVH is encouraging owners to implement good biosecurity measures when traveling with their horses and in general. Basic recommendations include not sharing any equipment among horses without first cleaning and disinfecting (1:10 bleach). Most disinfectants do not work in the face of organic debris (dirt, manure, etc.), so the cleaning step is critical.

Vaccination and the use of immunomodulators (Zylexis) may also be of use in reducing clinical signs and nasal shedding of the virus if administered prior to exposure.

The American Association of Equine Practitioners (AAEP) explains: “In horses infected with the neurologic strain of EHV-1, clinical signs may include: nasal discharge, incoordination, hind end weakness, recumbency, lethargy, urine dribbling and diminished tail tone. Prognosis depends on severity of signs and the period of recumbency.” Additional background information is on the AAEP website:

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