Thursday, May 24, 2001

Derby dreams give way to hope for survival

By Tim Bonfield
The Cincinnati Enquirer

        LEXINGTON, Ky. — Bred in hopes of winning the Kentucky Derby, an intensely sick newborn foal lay semi-conscious Tuesday in the hay of a veterinary clinic stall, its life depending on three medications dripping from IVs.

        For three weeks now, the staff of the Hagyard-Davidson-McGee clinic has been working at ground-zero of the worst horse-breeding crisis to hit the thoroughbred industry in at least two decades.

[photo] Roisin Shanahan feeds a sick throughbred at Hagyard-Davidson-McGee clinic in Lexington, Ky. The foal is one of hundreds affected by a mysterious ailment.
(Gary Landers photos)
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        This still-unexplained problem has caused more than 2,000 equine miscarriages and stillbirths since April 28. The industry could take an economic hit exceeding $150 million, prompting Kentucky's senators to propose legislation that would help horse breeders seeking federal disaster assistance.

        Especially here, in the No. 1 thoroughbred-breeding site in the world, it seems hard to accept that such carnage could be caused by something seemingly as harmless as a caterpillar.

        Cyanide poisoning linked to the possible consumption of Eastern tent caterpillars stands as the latest leading theory on Mare Reproductive Loss Syndrome, a mysterious ailment that has shocked the horse-breeding capital of the world, just 85 miles south of Cincinnati.

        “Caterpillars!? Wow, I thought they rejected that,” said veterinary technician Lynne Hewlett as she moved from stall to stall with two other staffers tending nine sick foals.

        It was worse in early May.

        “Right around Derby Day, we got slammed,” Ms. Hewlett said. “It was so hard to come in here and lose two, three or four foals a day.”

        Scientists at the University of Kentucky's Gluck Equine Research Center have been racing to figure out what's killing the foals. They've checked for viruses, bacteria, even toxic molds that might have been growing on pasture grass.

    University of Kentucky scientists are studying whether a wave of miscarriages and still-births creating a crisis in the state's horse industry has been caused by the Eastern Tent Caterpillar.
    Eastern Tent Caterpillars prefer eating Black Cherry leaves, which have a naturally high concentration of cyanide, a poison that can concentrate in the caterpillar.
    Initial tests reveal that the caterpillars can contain enough cyanide to kill four or five mice.
    An unusual weather pattern, involving a late April freeze, may have forced the caterpillar to migrate from trees hurt by the weather during the breeding season.
    While migrating, pregnant mares may have consumed the caterpillars, from eating them with pasture grass or drinking some as they congregated on water troughs.
    The cyanide may have harmed pregnancies by poisoning early fetuses, and by playing havoc with the placenta in late-term pregnancies, forcing premature births.
    As labs try to test this theory, several questions remain, including why haven't cattle or other livestock been harmed by the caterpillars?
        But now, they're focusing on a common backyard pest.

        “These are all theoretical constructs, but we are pursuing very actively that the Eastern tent caterpillar may be involved,” said Dr. Thomas Tobin, a veterinarian and toxicologist leading the lab research at UK.

        The syndrome has affected all types of horses from high-priced thoroughbreds in Kentucky to common breeds raised on small farms in Ohio, West Virginia and other states. Here's how the caterpillar theory may explain the losses:

        The Eastern tent caterpillar is a soft, slightly fuzzy black caterpillar with a white stripe that gathers by the hundreds and thousands to make large silk tents in trees.

        The caterpillars can nest on several kinds of trees, but theyprefer the leaves of black cherry trees. Turns out that those leaves can contain cyanide, a deadly poison when concentrated in high doses.

        The caterpillars absorb the cyanide as they eat but are not affected by it. However, recent UK lab tests indicate a caterpillar fed exclusively on black cherry leaves can contain enough poison to kill four or five mice, Dr. Tobin said.

        All this has been true as long as there have been cherry trees. So why would it hurt horses this year in record-setting numbers? Dr. Tobin said unusual spring weather in Kentucky and other states may have played a role.

Weather a factor
        Warm temperatures in March and early April may have allowed the caterpillars to multiply with abandon. Then a late April cold snap may have hurt the cherry trees, forcing armies of caterpillars to migrate in search of other food.

        Pregnant mares may have consumed unusually high numbers of the caterpillars as the bugs marched across pasture grasses, along fences and over water troughs, Dr. Tobin said.

        The cyanide doses were not high enough to kill any mares, but the poison may have been strong enough to hurt not one but two “crops” of foals.

        The gestation period for horses is about 11 months. On the same farms, the cyanide may have caused some mares — impregnated last year — to suffer premature births and stillbirths by playing havoc with the placenta, the source of blood and nutrients for a yet-to-be-born foal.

        However, even more mares — impregnated this year to give birth next season — have lost new fetuses barely two months into pregnancy. The cyanide might simply have stopped their hearts, Dr. Tobin said.

        A similar weather pattern occurred in 1980 and 1981. Those years also resulted in a spike in foal deaths, although not as severe as this year, Dr. Tobin said.

        To test the caterpillar theory, UK scientists this week sent out requests for samples of mare colostrum (the first milk they produce for newborns). And since no living tent caterpillars could be found in or near Kentucky, some were shipped from upstate New York for analysis.

        Results could be ready by week's end, Dr. Tobin said. But farm owners in Kentucky haven't been waiting for details.


        When scientists started talking weeks ago about mycotoxins in the pasture grass, farm owners started limiting the time mares spent in pasture and paying extra to provide mares with special, mycotoxin-absorbing feed. Some owners even started hauling pregnant mares as far as Florida.

        And now, just days into studying the caterpillar theory, staff at the Hagyard-Davidson-McGee clinic say they've heard of farm owners chopping down all the black cherry trees on their land.

Legendary farm hurt
        For many years after winning the Triple Crown in 1973, the legendary Secretariat stood at Claiborne Farm, one of the storied horse farms surrounding Lexington. Now, 325 mares and 16 stallions, including Go for Gin (1994 Derby winner) and Unbridled (1990 Derby winner) roam its 3,000 acres of rolling bluegrass and black plank fences.

[photo] Some of these maiden mares at Claiborne Farms in Paris, Ky., lost their foals to Mare Reproductive Loss Syndrome.
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        Claiborne managers say they haven't been hit quite as hard as some farms, but they have been hit. The farm lost one late-term pregnancy and 15 foals during early pregnancies — 11 were maiden mares (first-time breeders) grazing in two 80-acre fields.

        “We were thinking for a while that maybe the young maidens were more sensitive to whatever's going on,” said brood mare foreman Charles Koch. “Now, we're hearing it may not be the grass at all, that it might be the caterpillars, or something about the weather. Who knows?”

        Damage hasn't been limited to Kentucky thoroughbreds.

        In Ohio, where horse breeding isn't a big industry, veterinarians have reported 79 foal deaths to experts at Ohio State University. The losses have been concentrated in 12 southeast Ohio counties, all along the Ohio River, said Dr. Grant Frazer, an animal reproductive expert at Ohio State.

        “A lot of our reports are involving individual mares on small farms. But for those individual horse owners, the losses are very real,” he said.

        At one farm raising Belgian horses in Athens, Ohio, all seven mares lost their foals. At another farm in Athens County, all 13 ponies lost their pregnancies, Dr. Frazer said.

        The full extent of damage in Ohio may not be known, in large part because less testing is going on.

        Small-time horse owners often don't have the money for repeated ultrasound tests that have detected early pregnancy losses in Kentucky. They also don't have the time or money to ship dead foals to the state's diagnostic center in Reynoldsburg, even though the state has reduced its testing fees.

Deaths are slowing
        ┘Dr. Frazer said he has started to hear more about the caterpillar-cyanide theory. But he hasn't accepted it as the answer.

        “For the moment, it's just one more theory,” Dr. Frazer said.

        If the problem was caused by caterpillars, it could be reassuring news for the industry, Dr. Tobin said. That's because it would be relatively easy for horse farms to get rid of their cherry trees and to spray to kill any tent caterpillars they find next season.

        Meanwhile, the rate of miscarriages and foal deaths appears to be slacking off. In early May, as many as 10 to 25 dead foals a day were being shipped to the UK Livestock Disease Diagnostic Center. On Tuesday, only one dead foal was delivered.

        It remains difficult to tell whether the declining losses reflect a natural end of the crisis, or just the tail end of the breeding season. Still, the caterpillar theory makes some sense, said Dr. John Steiner, a reproductive specialist with Hagyard-Davidson-McGee.

        “A few weeks ago they were everywhere ... all over the fences and gates and on the ground,” Dr. Steiner said. “But they're gone now. If it was the caterpillars, it should be over by about now.”

        The problem is big enough that horse breeders are seeking federal disaster relief. And Kentucky politicians are getting involved.

        Republican U.S. Sens. Jim Bunning and Mitch McConnell of Kentucky are planning to introduce legislation to allow the U.S. Department of Agriculture to provide low-interest loans to horse farms, which department officials said is not allowed under current laws.

        As they seek answers, some horse farmers and scientists have joked about taking odds on what the cause of this year's disaster will be.

        Coming around the final turn, “Caterpillar Theory” is leading by a nose over “Mycotoxin-in-the-Grass.” But even Dr. Tobin agrees that “Who Knows?” is still riding hard on the outside.

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