The source of the "Foal Loss Syndrome" or "Mare Reproductive Loss Syndrome" (MRLS) that has so dramatically affected the equine breeding programs in Kentucky and stymied research scientists for a while has finally been tracked down! We heard about it in Kentucky because of the prominent industry that encompasses horses in that area. But, in fact, the syndrome occurred throughout the Ohio River Valley, affecting horse breeding establishments in several states.
There were three major factors that contributed to this problem, and they had to come together at just the right time to cause the early ending of pregnancy and loss of foals. Those factors were cherry trees, weather, and Eastern tent caterpillars.
First, let's look at the cherry tree. This tree's leaves naturally contain trace amounts of cyanide. That's right, the poison, cyanide.
Now, let the weather come into play. This year, the leaves came out and everything was fine. Then, there was a cold snap followed by a dry spell. This caused stress on the leaves. This stress caused a higher than normal concentration of cyanide in the leaves.
Then, along came the Eastern tent caterpillars. These caterpillars prefer cherry tree leaves and ate them to their hearts' content, dropped to the ground and went on their merry way in search of cocoon building sites. HOWEVER, as they ate, they ingested major quantities of cyanide, which they left in their excrement in the horse pastures.
Again, we have the weather's impact. Due to the dry spell, the horses were grazing much closer to the ground than they normally do. Had there been rain, the grass would have been taller. And a good rain would have diluted the effect of the excrement and/or washed it off the grass.
As it happened this year, the mares were grazing close to the ground and ingested the cyanide which caused the "spontaneous abortions" and early foal loss syndrome.
The problem has pretty much passed for this foaling season, but some pundits expect there will be a glut on the market of cherry lumber for furniture manufacturers!
We have just received information, dated May 29, that horse industry representatives have approached the USDA and Congress concerning the possibility of low interest (4%) loans for breeders who have suffered substantial losses due to this syndrome.
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Mare Reproductive Loss Syndrome
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