Mare Reproductive Loss Syndrome

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9th May 2005

In the northern hemisphere spring of 2001, a disease of unknown origin caused thousands of mares in central Kentucky to abort their foetuses wiping  out approximately one-third of The States entire foal crop that year – or about
2,700 foetuses. Hundreds of other mares produced sickly foals that later died – most of the mares never showed any sign of illness, except perhaps for a slight fever. The abortions occurred primarily between April and June, and by
the time the mares lost their foetuses it was too late in the season to wait for them to come into heat and breed them again.

For many commercial thoroughbred breeders, the mysterious wave of foetal and foal deaths known as Mare Reproductive Loss Syndrome, was the equivalent of the 1929 stock market crash, especially for those who had borrowed heavily against returns they had expected those foals to make at future auctions. The Kentucky Department of Agriculture estimates the disease’s total economic impact, including stud fee losses, future auction losses and the value of the dead foals among other things, at more that US$300 million.

Farms tried to explain to clients why their fat, dappled and healthy mares had without warning, expelled their foetuses, but there was little to go on. Some scientists thought it might have been a weather-related bloom of mycotoxins
in the pastures and so breeders brought their mares in from pastures and fed them hay instead. Other researchers suspected the culprit was a massive springtime infestation of Eastern Tent Caterpillars, a compelling theory that
sent farm workers out with insecticides and blow torches to rid their trees of the silky, bag-like nests. When someone pointed out the caterpillars ate cherry leaves which were known to produce cyanide, breeders hacked down the pink flowering trees. In fact, no-one really knows why the abortions occurred and as they scrambled to eliminate every possible culprit, the professional breeders were left reminding their clients of a truism that often got overlooked in the golden dream of million dollar sale prices. Thoroughbred breeding is an agribusiness and like every other kind of
farming it is subject to the whims of nature. Mares, it turns out, are more like farm fields than factories.

Taken from:-
The Home Run Horse
Author: Glenye Cain
Available from amazon.com
Published 2004 by the Daily Racing Form Press
100 Broadway, 7th Floor
New York NY 10005.