Does Ultrasound Give Clues to Abortion Cause?

Hagyard-Davidson-McGee veterinary associates worked with the University of Kentucky (UK)he latest project that has associated Eastern tent caterpillars (ETC) and mare reproductive loss syndrome (MRLS). Drs. Nathan Slovis and Thomas Seahorn, both internal medicine specialists at Hagyard-Davidson-McGee, assisted in the project conducted by the University of Kentucky. Their role was fetal ultrasonography. “We measured placental thickness, looked at echogenicity of amnionic and alantoic fluids, and looked at the biophysical parameters of foals such as heart rate, movement. We also looked at the umbilical cord (where there have been lesions in post mortem laboratory findings),” said Slovis.

The two veterinarians did not know which mares were in the control group and which were being given solutions containing ground-up caterpillars. They went out to the UK experimental farm every other day to ultrasound mares to see if they could discover any clues that might be early indicators that the unborn foals were exposed to toxins from the caterpillars.

In two of the mares, Slovis noted, there was a tremendous increase in fetal heart rate before the mares aborted. Slovis said the fetal heart rates were twice the normal heart rate of a fetus. “We knew those were stressed,” he said. “But this was a blinded study, so we had no idea who was being treated. Those two stressed foals--we were informed later that those mares aborted.”

Slovis said that otherwise the ultrasound exams didn’t give any early indications that these mares were being exposed to harmful substances and there were no indications that could help horse owner on the farm. The veterinarians are still reviewing the recorded examinations in the hope of discovering some early clue to the late term abortions.

However, said Slovis, “By the time we saw problems, like the increased heart rates, it was probably too late to do anything.”

Slovis said researchers and veterinarians still don’t know what part of the caterpillar is toxic. Is it the hairs? The organ structure? He said this and previous studies have correlated caterpillars with abortions. “That’s pretty much all you can say,” he added.

He said some people, including himself, had been doubtful about the role of Eastern tent caterpillars in MRLS, but that this study further confirms the association of caterpillars and abortions.

“People next year should take it more seriously,” recommended Slovis. “I kind of shrugged it off this year, but people should get more aggressive to get rid of caterpillars.”

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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