Md. urges vaccination of horses

August 22, 2000

Md. urges vaccination of horses

By ANDREW SCHOTZ / Staff Writer

Maryland's state veterinarian is urging horse owners to vaccinate their horses against encephalitis after five cases of the disease were confirmed in southeastern Virginia.


The suggested waiting period between Eastern equine encephalitis vaccinations has been cut in half - from one year to six months - as a precaution, said Roger Olson, chief of the animal health program at the Maryland Department of Agriculture.

"The manufacturers of the vaccines do recommend administering boosters once a year, and under normal circumstances, that's probably adequate," Olson said. "But when we have an increased risk, we feel that horses who have not been vaccinated in the last six months should have a booster to ensure their protection over a dangerous period."

Eastern equine encephalitis is a viral disease that attacks the nervous system. Spread by mosquitoes, it can be fatal and there is no cure.


Symptoms include staggering, circling, depression, loss of appetite, fever and blindness.

It can affect birds, horses and humans.

"Owners of ratites (ostriches, emus and rheas), especially emus, should also consult their veterinarians about vaccination, because these birds are even more susceptible than horses," Olson said in a press release.

There have been no reported cases of Eastern equine encephalitis in Maryland, West Virginia or Pennsylvania.

West Virginia has not issued a warning about the disease "and I don't know that we will," said Lewis Thomas, the state veterinarian.

The state tries not to create unnecessary anxiety or panic and "You've got to have a valid reason for (issuing a warning)," he said.

There has been no cause for concern in Pennsylvania, according to Jon Casey, press secretary for the state's Department of Agriculture.

He noted that the state has been monitoring the West Nile virus, another mosquito-spread disease, which is cropping up in New York and New England.

Each week, Pennsylvania tests a sample of 235 chickens and 32 horses along the state's eastern border for West Nile virus, Casey said.

"So far, everything is negative," he said.

According to Olson, the only known case of West Nile virus in Maryland came in 1989, when a crow tested positive in Baltimore.

Virginia is also encouraging horse owners to seek Eastern equine encephalitis vaccinations if their horses haven't received boosters in the last six months.

Five horses from southeastern Virginia have tested positive for encephalitis since July 31 and three others have been negative, according to Elaine Lidholm, the director of communications for the Virginia Department of Agriculture and Consumer Services.

Testing on a ninth horse was still under way, she said Monday.

The first horse to test positive was a Belgian draft horse near Suffolk, Va. The horse was about five months old, disproving the notion that horses under six months don't need the encephalitis vaccine, Lidholm said.

Amber Smith, a technician at Valley Equine Associates, a veterinary clinic in Ranson, W.Va., said the clinic has administered only one or two vaccines since the Virginia outbreak began.

There are about 1,000 to 2,000 horses in the Charles Town, W.Va., area, home of the race track, according to Thomas, the state veterinarian.

Smith said Valley Equines Associates offers two standard series of shots for horses. One is a five-way vaccine for Eastern and Western encephalitis, influenza, tetanus and a respiratory infection called "rhino."

The second series combines vaccines for Potomac fever and rabies, Smith said.

Olson said Eastern equine encephalitis usually emerges in July or August. "This is a critical season to be protected," he said.

Agriculture officials recommend spraying insecticides, removing animals from mosquito-infested areas and destroying sources of standing water, which attract mosquitoes.

Olson said people looking for more information on vaccinations can call the animal health laboratories in Frederick at 301-663-9528 or in Oakland at 301-334-2185.

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