EHV Update: New Cases in Los Angeles, Ventura & Marin Counties

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New equine herpes virus cases, in Los Angeles and suburban Ventura County and San Francisco suburban Marin County, were reported Saturday by the California Department of Food and Agriculture, a day after the U.S. government confirmed seven horses have died or been euthanized in the outbreak in a vast area of the western United States and Canada.

California reported 16 confirmed cases of EHM that is caused by the highly contagious neurological EHV-1 virus, six more than was reported Friday by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service. The positive confirmed cases reported by California were located in the counties of Amador (1), Glenn (2), Kern (2), Los Angeles (1), Marin (1), Napa (1), Placer (2), Plumas (1), Shasta (1) and Stanislaus (3) and Ventura (1) .

The new cases bring to 39 confirmed and 53 suspected cases of the virus that has affected horses participating in National Cutting Horse Association’s Western National Championships in Ogden, Utah two weeks ago. No horses in other disciplines are reported to have been affected.

EHV-1/EHM  confirmed and suspected cases or deaths have been reported officially in Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oklahoma, Oregon, Texas, Utah, Washington and Wyoming. Separately, the Canadian provinces of British Columbia and Alberta reported another four cases.

Several horse shows–including several dressage competitions–and clinics have been cancelled or postponed throughout western states, including clinics for jumpers and reining in Colorado. Three Oregon Dressage Society events were postponed and a fourth was moved. U.S. Equestrian Federation sanctioned competitions Las Vegas Dressage Spring Fling III scheduled for Saturday and Sunday and a one-day competition in Kirkland, Washington, announced cancellations because of the EHV outbreak.

However, two competitions in California, a CDI1* at Woodside and a California Dressage Society show at San Juan Capistrano, went ahead.

Colorado and Wyoming have imposed restrictions on horses entering the state, but other states with horses affected by EHV have not.

An outbreak of the equine herpes virus in South Florida in December, 2006, just weeks before the start of the winter dressage, hunter-jumper, polo and Thoroughbred racing circuits led to the deaths of six horses.

Due to the huge area directly impacted by the latest outbreak–the eight states where confirmed or suspected cases have occurred is almost one-third the total land mass of continental United States–the U.S. Department of Agriculture agreed to a request by the American Horse Council and American Association of Equine Practitioners to coordinate information gathering and distribution among states.

The U.S. government report stated that horses died or were euthanized in Arizona (1), California (1), Colorado (2), Idaho (2) and New Mexico 1.

In addition to the deaths, cases of EHV-1 or EHM by state: California (10 confirmed), Colorado (9 confirmed, 19 suspected); Idaho (1 confirmed, 16 suspected), Montana (1 suspected), Nevada (3 suspected), New Mexico (2 confirmed, 4 suspected), Oklahoma (1 suspected), Oregon (2 confirmed), Texas (1 confirmed, 1 suspected), Utah (5 confirmed, 3 suspected), Washington (3 confirmed, 4 suspected) and Wyoming (1 suspected).

Equine Canada reported three cases in British Columbia and one in Alberta.

Biosecurity measures recommended for horses who attended the Odgen event or may have come in contact with horses affected include:

-Isolate exposed horse a minimum of 30 feet away from all other horses (round pen if necessary) for 21 days;
-Monitor temperature twice a day for 14 days;
-Immediately report temperatures over 102F (39C) to your private veterinarian;
-Use separate equipment, bucket, halters/leads for isolated horse;
-Wear protective clothing when handling isolated horse–coveralls, boot covers, gloves. Do not use same clothing with other horses;
– Ideally, use separate personnel for isolated horses, and
-Restrict movement.

Key to limiting the disease from spreading is Isolation of sick horses. Sick horses are shedding virus and should be removed from exposing additional horses.

Symptoms can include fever, sneezing, slobbering and other mild symptoms. Serious cases of the disease are rare, but can include staggering, hind-end paralysis and even death of the horse.

The virus can usually survive for about a week on surfaces, though under the optimum conditions could last as long as 30 days.

The American Association of Equine Practitioners said:

• There is no specific treatment for EHV-1, although antiviral drugs (i.e. valacyclovire) may have some value before neurological signs occur.

• Non-specific treatment may include intravenous fluids, and other appropriate supportive therapy.

• The use of anti-inflammatory drugs (NSAIDs) is strongly recommended.