Equine Virus Outbreak Causes Changes For Local Horse Owners

Update 6/1:

As of 12 noon, the California Department of Food and Agriculture (CDFA) site lists a total of 20 confirmed EHV-1 cases statewide. None are in San Mateo County.

The breakdown by county:

Amador (1), Colusa (1), Glenn (3), Kern (2), Los Angeles (1), Marin (1), Napa (1), Placer (3), Plumas (1), Sacramento (1), Shasta (1), Stanislaus (3) and Ventura (1).

16 out of the 20 cases were in Ogden, Utah participating in the Western National Championships of the National Cutting Horse Association.

All 20 cases are currently under a state quarantine.

A local horse-riding facility has closed its gates due to concerns about the recent outbreak of equine herpes virus in western portions of the United States.

The Mounted Patrol of San Mateo County, a charitable not-for-profit organization that owns and manages 23 acres on Kings Mountain Road in Woodside, will not allow riders onto their property for the time being.

"We decided that since we have 20 horses boarded here, just for the safety of those horses, we thought that we would quarantine our area and not let any horses in, and not take our horses out until we got more definitive information regarding this disease," says Terry Welcome, manager of Mounted Patrol. "We have a vet that is a member, and it was his suggestion that we do this.  We don’t know how long this is going to happen; after 21 days everything should be okay.  This is a precautionary measure."

The outbreak of EHV-1 (Equine Herpes Virus) originated during an early May cutting-horse event in Ogden, Utah. Thirteen horses that attended the Utah event have been confirmed to have EHV-1; one in California had to be euthanized.

An 8 a.m. Friday update on the website of the California Department of Food and Agriculture states:

• There are three new confirmed cases of Equine Herpes Myeloencephalopathy caused by EHV-1.  The total number of confirmed cases in California is at 13.
• All confirmed California cases are cutting horses who participated in the Ogden, Utah National Cutting Horse Association’s Western National Championships.
• The positive confirmed cases are located in the following counties: Amador(1), Glenn(2), Kern (2), Los Angeles(1), Napa(1), Placer (2), Plumas (1),  and Stanislaus (3).
• Currently, in California, there is no evidence of EHV-1 disease spread outside the cutting horses who participated in the Ogden, Utah event.

"Napa is the closest outbreak that has been identified, and the Ogden, Utah competition was April 30-May 8, and that’s more than two weeks ago, beyond the incubation period," says Rebekah Witter of On A Lark Farm in Woodside.

"If they’re getting new outbreaks, that’s unnerving, you know, because last I heard, there were ten outbreaks, and if there are now 13, I’d want to know where those last three were discovered."

The Horse Park at Woodside has revised precautions on its website to horse-owners in the area: "We are not stating this is only a cutting horse issue, it affects the entire equine industry. The fact is that 'to date' the outbreak in California is only isolated to the cutting horse entries that attended the event in Ogden, Utah."

Pam McReynolds owns Williams Ranch on La Honda Road in Redwood City. "It's really not an issue for me, because most of my horses are retired, and my stalls are full," says McReynolds. "I'm not bringing in any (new) horses;  if someone wanted to take one of the horses outside of the ranch to ride, hmmm, that's a tough one.  I'd have to think about it."

Local horse owners in San Mateo County are urged to be cautious, but not to panic. If a horse is found with a higher than normal temperature, isolation is recommended, along with appropriate biosecurity measures and the avoidance of horse-to-horse contact.

Witter points to the important need for cleanliness. "It’s the same sort of epidemiological precautions you make even though there haven’t been any horses identified in this particular area," she says. "This is transferred by touch; it doesn’t necessarily be horse to horse, it can be horse to human, human to horse. Humans don’t get it, but humans can transfer it by physical contact."

Terry Welcome points to a possible scenario. "It’s an airborne virus that can be transferred. A horse could sneeze on you, and get the virus on your clothes. And if you went up to another horse, another stable, and rubbed up against him, or he rubbed up against you, there’s a possibility it could be transferred at that time."

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.