UC Davis

Fear of equine virus cancels California events

By May 21, 2011

By Stacy Finz

The nation’s $39 billion-a-year equine industry has been racked with a deadly virus that has killed at least seven horses — one in Bakersfield — and sickened another 37 in eight states, including 14 in California.

State and federal officials continued Friday to try to pinpoint the original source of a mutated form of equine herpes virus-1, known as equine herpes myeloencephalopathy.

The neurological illness leads to interference with the blood supply, causing tissue damage and a subsequent loss in normal brain and spinal cord function. Other symptoms include high fever, lethargy, weakness and lack of coordination.

In the meantime, equestrian associations and stables across the country have canceled shows, exhibitions and competitions to reduce the risk of spreading the virus. California’s equestrian community is also postponing horse events until it’s safe to resume. There are 698,000 horses in California, a business valued at $4.1 billion, according to the American Horse Council.

“We first became aware of the disease in the 1970s,” said Dr. Kent Fowler, an equine veterinarian and the animal health branch chief for the California Department of Food and Agriculture. “In the last decade we’ve seen an increase in these types of varied strains.”

There is no specific cure for EHM. But veterinarians at UC Davis, which is housing two of California’s infected horses in a maximum-security barn, said they are treating them like they would humans, with a version of the popular herpes drug valcyclovir, commonly known as Valtrex.

The other 12 horses also have been placed under quarantine by the CDFA, which is closely monitoring the animals. As many as 200 horses that may have been exposed to the contagious virus are also being watched for early stages of the bug, including nasal discharge, hind-end weakness and urine dribbling.

EHV-1 is not transmissible to humans, but people can spread it to horses after touching an infected animal and its equipment and feed, Fowler said.

So far, authorities have traced the virus to the National Cutting Horse Association’s Western National Championships competition in Odgen, Utah.

The annual event, where riders and horses are judged on their ability to separate a calf from the herd and are awarded hundreds of thousands of dollars in prize money, was held from April 30 to May 8. The virus has a two- to 10-day incubation period, Fowler said.

“There are still parts of the puzzle we don’t know,” he said. “Federal epidemiologists are following the trail.”

What investigators do know is that 54 American quarter horses from California attended the Utah show and 15 came back sick, Fowler said. Five of the 15 showed neurological signs of the virus and nine have high temperatures, he said. The Bakersfield horse had to be euthanized after it fell to the ground and couldn’t get up.

Some of the animals that returned from Utah attended another show in Kern County, where 200 horses were in attendance, said Dr. Gary Magdesian, an associate professor of equine medicine and an infection control officer at UCD. It’s unknown how many of those animals may have been exposed to the germ.

Owners and handlers are being told to keep tabs on their horses’ temperature. For any horse with a temperature 102 F or higher, a veterinarian should be notified.

The last big outbreak was in 2006, when six horses died in Florida.

“It pops up every year in this country,” Magdesian said. “It’s one of the worst diseases a horse can get.”

— Reach Stacy Finz at [email protected]

San Francisco Chronicle

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