Hair remnants, resembling Eastern tent caterpillar (ETC) setae (hair-like projections on the outside of the caterpillar), were found embedded in the submucosa of the digestive tract of one mare fed ETC larvae. Examination of this mare represents the initial step of a controlled experiment with the purpose of investigating the role of the ETC exoskeleton (cuticle) in MRLS (see also Deductive Investigation of the Causes of Mare Reproductive Loss Syndrome: Experiment 4, June 6, 2003).

The setae-like fragments are similar to those found in gilts fed ETC in a previous experiment. Two of the five gilts fed ETC had fetal loss (see Eastern Tent Caterpillars Cause Abortions in Pregnant Pigs, Sept 5, 2003). In both this mare and the affected gilts, presence of setae were associated with an inflammatory reaction. No such fragments were found in gilts not fed ETC