MRLS Update: 'We Do Not Understand This Disease'
by Kimberly S. Brown
Date Posted: 1/6/2004 9:42:08 PM
Last Updated: 1/7/2004 7:36:49 AM

"In the final analysis, we do not understand this disease," said Dr. Bruce Webb, an entomologist at the University of Kentucky who has been a leading researcher into the problem of Mare Reproductive Loss Syndrome.

Webb and Dr. Karen McDowell, a reproduction specialist from the Gluck Equine Research Center at the university, presented a synopsis of the MRLS research conducted thus far to a small, invited gathering of representatives of about 40-45 Thoroughbred farms. The meeting, held at Keeneland this afternoon (Jan. 6), was designed to educate those who could help raise $800,000 or more to fund studies of the mechanisms of MRLS for the next 12-24 months. The funds will be overseen by the Kentucky Thoroughbred Owners and Breeders Foundation. Any monies not used for MRLS research would stay in the foundation to fund reproductive research and to be an emergency fund in case of a future crisis.

Jimmy Bell, one of the leaders of the group working to establish this research fund, said, "It is incumbent on us to see this research cross the finish line. It is an opportunity for us as a committed group to step forward to help close the gab of what has cost us a conservative half-billion dollars (the estimated losses to the state from MRLS)."

Dr. Richard Holder, a private practitioner and president of the Kentucky Association of Equine Practitioners, said researchers need to look for the mechanism of action between the caterpillars and the dead fetus. He pondered aloud whether a vaccine can be developed, or a treatment can be devised to save pregnancies that are threatened.

Since it was discovered that the setae (hairs) of caterpillars penetrate the mucosal lining of the alimentary tract (from the mouth to the anus), the theory has been that bacteria found normally in the horse's digestive tract are allowed into the bloodstream, where they migrate and attack the fetus, eyes, and heart. Proposed research would feed fluorescent bacteria (a Streptococcus) and Eastern tent caterpillars to pregnant mares and trace the bacteria through the horse's body. This should show the pathogenesis of the disease. This experiment alone will cost about $120,000.

Interestingly, Webb had just received new images over the holidays that showed something unique about the setae and bacteria. He had taken setae and incubated them with bacteria. Setae are hollow on the end closest to the caterpillar, and solid at the tip. Under microscopic examination, he found that the setae contained bacteria inside the hollow portion. The bacteria did not, as he previously theorized, just cling to the outside of the hair.

However, Webb warned, that one finding does not mean that's how the bacteria are associated with setae and abortions. He did say that he was excited about the finding and thought it was significant in the overall understanding of the mechanism of this disease.

Bell said that one farm has committed to $100,000 in research funding, and five other farms have committed to $50,000 apiece. While that is a good start toward reaching the $800,000-plus goal, said David Switzer, executive director of the Kentucky Thoroughbred Association and KTOB, there needs to be a broad base of industry participation.

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