Invited review: the role of caterpillars in mare reproductive loss syndrome: a model for environmental causes of abortion.
Abstract: A new abortigenic disease, now known as mare reproductive loss syndrome (MRLS), significantly affected the horse industry in the Ohio River Valley of the United States in late April and early May of 2001 and 2002. In 2001, approximately 25% of all pregnant mares aborted within several weeks (over 3,000 mares lost pregnancies), and abortion rates exceeded 60% on some farms. Mare reproductive loss syndrome struck hard and without warning, it was caused by something in the environment, it was not transmitted between animals, and it was not associated with any known abortigenic agent or disease. These experiments demonstrated that horses will inadvertently consume Eastern tent caterpillars (ETC) when the insects are present in the pasture or other feedstuffs, and MRLS-type abortions were induced in experimental animals (mares and pigs) by mixing ETC with the feed of the animals. Eastern tent caterpillars are hirsute (hairy) caterpillars, and the only part of the caterpillar that caused MRLS abortions was the cuticle. The experiments revealed that the setae (hairs) embed into the submucosa of the alimentary tract creating microgranulomatous lesions. It is hypothesized that the alimentary tract lesions allow bacteria from the alimentary tract of the mare, principally streptococci, actinobacilli, and to a lesser extent enterococci, to invade the circulatory system of the mare. The bacteria then establish infections in tissues where the immune surveillance of the mare is reduced, such as the fetus and placenta. Fetal and placental fluid bacterial infections lead to fetal death and abortion characteristic of MRLS. Inadvertent ingestion of ETC by pregnant mares causes MRLS. Currently the only known means to prevent MRLS is to avoid exposure of horses, particularly pregnant mares, to ETC and probably most hirsute caterpillars.
Publication Date: 2010-01-15 PubMed ID: 20081071DOI: 10.2527/jas.2009-2584Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- Non-P.H.S.
- Review
Summary
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The study investigates a disease caused by environmental factors that leads to prominent abortions in mares, known as Mare Reproductive Loss Syndrome (MRLS), primarily linked to the consumption of Eastern Tent Caterpillars (ETC).
Background of Mare Reproductive Loss Syndrome (MRLS)
- This research addressed a new disease, known as MRLS, which heavily impacted the horse industry in the Ohio River Valley, USA, in April and May of 2001 and 2002.
- In 2001, about 25% of pregnant mares experienced abortions within a few weeks, and the rate of abortion surpassed 60% in specific areas.
- MRLS caused unexpected and immense damage; it was not transmitted between animals and was not linked to any previously known abortigenic agent or disease.
Role of Eastern Tent Caterpillars (ETC)
- The research showed that horses tend to unknowingly consume Eastern Tent Caterpillars (ETC) when the insects are present in their feeding grounds.
- When ETC was mixed with the feed of the experimental animals, it resulted in MRLS-type abortions.
- The only part of the ETC that caused MRLS was the cuticle, which embedded into the submucosa of the horse’s digestive system, creating minor granulated lesions.
Theoretical Implications and ETC Impact
- Researchers hypothesize that these lesions in the digestive system allow bacteria, primarily streptococci and actinobacilli, and to a lesser extent enterococci, to enter the horse’s circulatory system.
- The bacteria then create infections in body tissues where the horse’s immune response is weakened, such as the fetus and placenta.
- These bacterial infections in the fetal and placental fluid cause fetal death, which leads to abortions observed in MRLS.
Prevention of MRLS
- This study demonstrates that accidental consumption of ETC by pregnant mares causes MRLS.
- Presently, the only known method to prevent MRLS is to avoid exposing horses, especially pregnant mares, to ETC and other haired caterpillars.
Cite This Article
APA
McDowell KJ, Webb BA, Williams NM, Donahue JM, Newman KE, Lindemann MD, Horohov DW.
(2010).
Invited review: the role of caterpillars in mare reproductive loss syndrome: a model for environmental causes of abortion.
J Anim Sci, 88(4), 1379-1387.
https://doi.org/10.2527/jas.2009-2584 Publication
Researcher Affiliations
- Department of Veterinary Science, University of Kentucky, Lexington, USA. kmcd@uky.edu
MeSH Terms
- Abortion, Veterinary / etiology
- Animals
- Colon / drug effects
- Colon / pathology
- Environment
- Female
- Horse Diseases / etiology
- Horses
- Larva / pathogenicity
- Moths / pathogenicity
- Pregnancy
- Swine
- Swine Diseases / etiology
- Syndrome
Citations
This article has been cited 2 times.- Bischoff K, Moiseff J. Equine feed contamination and toxicology.. Transl Anim Sci 2018 Feb;2(1):111-118.
- Chapuis RJJ, Ragno VM, Ariza CA, Movasseghi AR, Sayi S, Uehlinger FD, Montgomery JB. Septic fibrinous pericarditis in 4 horses in Saskatchewan following an outbreak of forest tent caterpillars in 2017.. Can Vet J 2020 Jul;61(7):724-730.
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