Two weeks after the California Department of Food and Agriculture (CDFA) reported that Equine Herpes Virus (EHV-1) has been confirmed in 10 horses in California, horse owners are being advised to avoid nonessential transport of their animals.
New information indicates the EHV-1 infection outbreak was centered around horses that were present at the National Cutting Horse Association's Western National Championships (NCHA) held at the Golden Spike Event Center in Ogden, Utah from April 30 to May 8 and/or the Kern County Cutting Event in Bakersfield, on May 13. The outbreak has included cutting horses that did not attend either of the above events but have come into contact with horses returning from those events.
In Stanislaus County three horses were discovered to have been infected with EHV-1. According to Taylor Vet Hospital veterinarian Craig Brooks, a stallion that had been at the Golden Spike event visited Taylor Vet Hospital in Turlock on May 13 for an unrelated reason. A day later the horse began showing symptoms such as loss of strength and urination problems.
It was later determined two other horses which were stalled at the same ranch as the stallion had contracted EHV-1. All three horses were quarantined at UC Davis on May 15 and Taylor Vet quarantined the area where the stallion stayed in the hospital.
"Right now it seems pretty well contained. We are advising horse owners to exercise caution and we are not recommending people take horses to shows for now. However, they can take horses for rides with a neighbor or something, just ensure the horses haven't been in contact with any horses that were at the Utah or Kern County events," said Brooks. "We understand horse owners are scared, but there is no need to be afraid, just exercise caution."
At this time it is unknown when advisories and biosecurity cautions will be lifted.
Equine Herpes virus is a contagious disease and may spread quickly among horse populations. EHV-1 is not transmissible to humans. Horse-to-horse contact, aerosol transmission, and contaminated hands, equipment, tack and feed all play a role in disease spread.
Early symptoms of EHV-1 include a rectal temperature of 102 degrees and above. Further advanced symptoms include the following clinical signs: nasal discharge, lack of coordination, hind-end weakness, lethargy, urine dribbling and diminished tail tone.
All California horses that have been in contact with an infected horse and show signs of disease or test positive for EHM will be placed under CDFA quarantine in order to limit spread.
The UC Davis Veterinary Medicine department suggests that managers of horse shows or events occurring in California during the coming weeks incorporate the following biosecurity measures to minimize the risk for all participants:
1. Event managers should create a short document for participants to sign upon arrival at the show grounds to confirm that their horses, mules, and burros attending the show/event have not attended or had prior contact with horses from the NCHA Championships in Ogden, Utah and/or the Kern County Cutting Event in Bakersfield, or been on the same premises with horses that have returned from these events. Horses that have attended, or been exposed to horses returning from either event will not be allowed to enter the show grounds.
2. Establish a "No Fever" policy for horses attending the event. Give the participants prior notice of the new "No Fever" policy before they arrive at the show grounds. Provide instructions for obtaining the horse's temperature and an index card on which to record temperature readings for each horse.
a. All horses will have temperatures taken twice daily and results will be posted on front of the stall/pen for inspection.
b. Any horse will be subject to random temperature check by the show veterinarian or designated member of the veterinary staff during the event.
c. Any horse with a fever of 102°F or greater will be removed from the event and premises immediately (i.e. within 2 hours of detection of fever).
d. If the owner cannot move the horse off the premises, a professional horse hauler contracted by the event will remove the horse to a designated isolation area at the owner's expense.
The California Department of Food and Agriculture has contacted all 54 exhibitors from California who participated in the Ogden, Utah event and asked them to isolate and monitor their horses for clinical signs of EHV-1.
There is no specific treatment for the virus.
"There is only supportive treatment, the best thing you can do is isolate the horse and stop the spread" said Karen Unger, a veterinarian at Pioneer Equine Hospital in Oakdale.
Treatment may include intravenous fluids, anti-inflammatory drugs and other appropriate supportive treatment. Immediate separation and isolation of identified suspect cases and implementation of appropriate biosecurity measures are key elements for disease control.
To contact Jonathan McCorkell, e-mail email@example.com or call 634-9141, ext. 2015.