Eastern tent caterpillars are numerous on our small Central Kentucky farm this year. They have defoliated the spring leaf growth on most of the wild black cherry trees and are now crawling around in great numbers on board fences, stone walls, and most points in between.
This makes a recent scientific publication all the more timely. In an invited review for the April issue of the Journal of Animal Science, the Gluck Equine Research Center's Karen McDowell, PhD, and co-authors from several University of Kentucky departments provided an overview of their scientific research. They indicate small hairs (setae) projecting from the cuticle of these caterpillars have a central role in the cause and progression of mare reproductive loss syndrome (MRLS). Combined with published studies from a number of independent groups, these data strongly suggest that the oral intake by horses of Eastern tent caterpillar cuticle and setae--and apparently another species of hirsute (hairy) caterpillars in Australia--causes MRLS in pregnant mares and less frequently other serious health problems, including pericarditis and endophthalmitis.
Since I study the musculosketetal system, any further discussion of insects and reproduction is risky. However, I do believe this example clearly illustrates the essential role of scientific research in advancing our knowledge of horse health and indeed all things related to equine science. Prior to the spring of 2001, MRLS had not been recognized as a clinical entity. Our current understanding of the epidemiology, pathology, bacteriology, immunology, toxicology, and clinical aspects of this disease has come through scientific research conducted over the last nine years. Are there additional questions and debate related to MRLS? Of course. This is to be expected and will always be the case for an interesting topic. There will always be more questions and alternative ideas.
Additional knowledge, however, can only come from new data generated through further research. We can question, we can speculate, we can debate, and sometimes we can even argue. In the end, though, a better understanding of MRLS or any other equine science topic (biomedical, management, economic, etc.) does not come from personal opinion, but from high quality and rigorous scientific research. In the absence of experimental data from well-designed studies, we have no mechanism to truly advance our knowledge and understanding.
James N. MacLeod, VMD, PhD, director of the UK Equine Initiative and Dickson Professor of Equine Science and Management and the John S. and Elizabeth A. Knight Chair at the Gluck Equine Research Center, submitted this commentary.
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Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.