10/03/2001 11:00PM

Preventive measures for breeders

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LEXINGTON, Ky. - With the 2002 breeding season set to open in February, the University of Kentucky has issued some suggestions for breeders hoping to guard against a recurrence of mare reproductive loss syndrome, the mysterious ailment that caused thousands of central Kentucky mares to abort this spring.

At a sold-out meeting of the Kentucky Thoroughbred Farm Managers' Club in Lexington Tuesday night, Dr. Scott Smith, dean of UK's college of agriculture, presented a draft outline of measures for farm managers to minimize risk factors for MRLS. But he acknowledged that the university has yet to determine what caused the wave of abortions from April to June.

"We need to look beyond the cause and plan for the coming breeding season," Smith told some 260 managers at the meeting. "The exact cause of MRLS remains unresolved. Several lines of investigation are being pursued."

Among the theories that have been blamed for the syndrome are: Eastern tent caterpillars carrying cyanide from the cherry leaves they eat into pastures; natural grass toxins produced during changeable weather patterns; poison hemlock ingested by mares; cyanide produced by white clover; and excessive nitrate concentrations in soil from fertilizers.

Smith discussed two strategies for dealing with a potential MRLS recurrence: monitoring conditions that could lead to the syndrome and minimizing risk factors that the university's epidemiological studies have identified for the syndrome.

Smith noted that the presence of wild cherry trees and caterpillars were substantial risk factors for the syndrome's occurrence on more than 130 farms the university surveyed this summer. He suggested that managers keep pregnant mares away from cherry trees and spray for caterpillars, factors that could be in play next spring.

"Preliminary egg counts indicate that the Eastern tent caterpillar presence in 2002 will be high again," Smith noted.

Smith also said that managers might consider mowing their pastures frequently and offering hay in pastures to minimize risk of exposure to possible grass toxins; increase the grass-to-clover ratio in pastures; restrict horses' pasture time when a hard freeze is expected after a warm period; and reduce mares' exposure to endophyte-infected tall fescue.

Smith also announced formation of an equine emergency management task force that will plan an environmental monitoring system for the 2002 breeding season, including development of an alert system that will notify managers when conditions are favorable for MRLS to occur.