College of Agriculture
Veterinary Science	Mare Reproductive Loss Syndrome Index Page
Keeneland Session

Mare Reproductive Loss Syndrome

Investigative and Data Analysis Summary
May 24, 2001

Dr. Thomas Tobin
Professor
University of Kentucky College of Agriculture
Maxwell H. Gluck Equine Research Center Department of Veterinary Science

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 1. Phytoestrogens:

1.1.  35 Pre-Derby Samples taken; 17 clover/mixed hay samples sent to Iowa State U. Test results suggest no significant pasture/clover concentrations of phytoestrogens.

2.1. Test results suggest no significant pasture concentrations of mycotoxins.

3.1. Test results suggest no significant pasture sources or concentrations of ergot alkaloids.

3.2. Necropsy results not consistent with ergot alkaloid intoxication.

4.1. Wilted Black Cherry leaves are well known to be toxic to cattle and horses. Wilting of leaves substantially increases the content and/or availability of cyanide.

4.2. Eastern Tent Caterpillar:

4.2.1. Well adapted to cherry leaves; Eggs deposited on tree and feeds and thrives on leaves.

4.2.2. Uses cyanide as a defense mechanism against predators.

4.2.3. This spring the black cherry trees were completely stripped of leaves; digestive tract of caterpillars is about 50 % effective.  Fecal material may contain cyanide precursors from black cherry tree.

4.3. Necropsy:

4.3.1. Early results of tissue analysis from late term foals suggests cyanide.

4.3.2. Cyanide causes death due to tissue anoxia; triggers a strong “gasp” reflex.

4.3.3. Necropsy results not inconsistent with death due to cyanide.

5.1. Re-confirm reports of cyanide in late term fetuses

5.2. Trace cyanide back from mares to black cherry leaves trees.