Caterpillar hair can cause abortions in Australian mares

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Lev Bely, 08.10.2012 18:18

Researchers from the University of Queensland, Australia, found out that caterpillar hair can cause foal death and abortions in Australian mares.

Dr Judy Cawdell-Smith and Professor Wayne Bryden, from the UQ's School of Animal Studies, discovered that pregnant mares contacted with hairy Oak Processionary (Thaumetopoea processionea) caterpillars tended to abort.

“This is an unusual form of abortion that was first reported in Australia in 2004 and is similar to a condition reported in Kentucky in 2002,” Dr Cawdell-Smith said.

“Researchers in Kentucky identified Eastern Tent Caterpillars as the cause of the US equine condition, Mare Reproductive Loss Syndrome.”

Similar miscarriage cases were also registered in the Hunter Valley in 2004.

“Studies conducted by veterinary epidemiologist, Professor Nigel Perkins, suggested the abortions were caused by caterpillars or poisonous plants,” Professor Bryden said. “No poisonous plants were found on any of the stud farms where mares aborted. Caterpillars were identified as the cause of the US problem but the same caterpillars don't exist in Australia. However, other related caterpillars were found on the affected Australian stud farms.”

“If you've ever seen a hairy caterpillar, it is unlikely that a horse would eat a whole one. What's more likely is that the caterpillar's exoskeleton — which is much harder to see in the grass — is picked up by the horse while it is grazing.”

“In our studies, both whole caterpillars and exoskeleton caused mares to abort.”

The study authors reckon that a swallowed caterpillar, or literally its hair, damages the intestinal wall of the horse, then bacteria get into the circulation and ultimately reach the fetus through the placenta.

“The subsequent infection caused by the bacteria in the fetus results in abortion,” Dr Cawdell-Smith said.

“These bacteria are found in the intestine of mares and normally don't cause a problem.”

“Interestingly, mares that abort have no ill effects or evidence of illness.”

The research was funded by the Rural Industries Research and Development Corporation and the Hunter Valley Equine Research Centre. Professor Bryden and Dr Cawdell-Smith have investigated this area since 2006.

The University of Queensland, http://www.uq.edu.au

Photo: Malacosoma americanum caterpillar, Lynette Schimming, http://eol.org

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