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

Mare Reproductive Loss Syndrome

UK Livestock Disease Diagnostic Center Summary
May 24, 2001

Dr. Lenn Harrison
Director
University of Kentucky College of Agriculture

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To date 9,484 tests/assays and procedures have been done on the fetuses and foals (<7days of age). Results of laboratory examinations/testing of fetuses:

1. Virologic Examinations: All tests are negative for viral diseases.

2. Bacteriologic Examinations: Bacteria for two genera have been isolated from approximately 78% of fetuses. These isolates are Streptococcus species 56% and Actinobacillus species 18%. The Streptococcus species and Actinobacillus species have both been isolated from 2% of the fetuses. These isolates are microaerophilic. They prefer a low oxygen environment.

3. Pathologic Evaluation: A consistent pattern of lesions has been identified in the fetuses and the amniotic sac of the placenta. The lungs of the fetuses have evidence of intrauterine toxic insult and inflammation. Also, the amniotic sacs have changes previously not recognized in equine placentas. The amniotic sac changes are being interpreted as having had a toxic insult and a secondary infection.

4. Toxicologic Examinations: All fetuses that have been tested are negative for nitrate/nitrite. Assays have not demonstrated any abnormal concentrations of elements in mare’s sera or fetal tissue.

The caterpillars tested May 4, 2001 were negative for cyanide. Retrospective inquiries indicate these caterpillars had not consumed cherry tree leaves (or any plant materials) for more than 6 hours. This is an important observation since caterpillars pass ingesta through the intestinal tract in about 6 hours.

A sample of preserved tent caterpillars taken April 20, 2001 is very strongly positive for cyanide.

A small set of selected tissue samples were sent on May 17, 2001 to the Toxicology Section, Laboratories of Veterinary Diagnostic Medicine, College of Veterinary Medicine, University of Illinois. Included in these samples were specimens of heart muscle, blood, pericardial fluid, liver and kidney. The distillation-ion specific electrode method has identified low levels of cyanide or a cyanide-containing compound in the heart muscle of these fetuses. This observation must be confirmed by further testing and research.