EXPERIMENTAL AND BASIC RESEARCH STUDIES
Exposure of mares to processionary caterpillars (Ochrogaster lunifer) in early pregnancy: An additional dimension to equine amnionitis and fetal loss
Article first published online: 4 MAR 2013
© 2013 EVJ Ltd
Equine Veterinary Journal
Volume 45, Issue 6, pages 755–760, November 2013
How to Cite
Cawdell-Smith, A. J., Todhunter, K. H., Perkins, N. R. and Bryden, W. L. (2013), Exposure of mares to processionary caterpillars (Ochrogaster lunifer) in early pregnancy: An additional dimension to equine amnionitis and fetal loss. Equine Veterinary Journal, 45: 755–760. doi: 10.1111/evj.12044
- Issue published online: 14 OCT 2013
- Article first published online: 4 MAR 2013
- Accepted manuscript online: 10 JAN 2013 06:50AM EST
- Manuscript Accepted: 28 DEC 2012
- Manuscript Received: 31 MAY 2012
- Rural Industries Research and Development Corporation
- Horse Programme
- Hunter Valley Equine Research Centre
- processionary caterpillar;
- equine amnionitis and fetal loss
Reasons for performing study
Equine amnionitis and fetal loss (EAFL) is an unusual form of abortion in mid- to late-gestation mares, first identified in Australia in 2004. It has been shown that both whole processionary caterpillars (Ochrogaster lunifer) and their shed exoskeletons can induce abortion in mares during midgestation. These abortions exhibited gross pathology and bacteriology results consistent with field cases of EAFL.
To determine whether exposure of mares to the shed exoskeletons of processionary caterpillars can induce abortion in the preplacentation (<35 days' gestation) and early placentation (45–60 days) stages of pregnancy.
In vivo experimental study.
Mares less than 35 days' gestation and between 45 and 60 days' gestation were exposed to a slurry of shed processionary caterpillar exoskeletons by nasogastric intubation. Mares were monitored by clinical examination daily. Transrectal ultrasonography was performed daily (control and treated preplacentation mares, treated early placentation mares) or every second day (control early placentation mares). Uterine swabs were collected from mares that aborted. All live foals underwent a clinical examination. Placentas were examined, with sampling for bacteriology and histopathology if appropriate.
Abortions occurred in treated mares in both experiments without signs of impending abortion. One mare aborted in the embryonic stage experiment and 2 in the early placentation experiment. Embryonic and fetal death was detected on transrectal ultrasonography prior to abortion. In the early placentation experiment, one foal was born 5 weeks preterm and was very small, with laxity of the tendons in all limbs. Enteric or environmental bacteria, consistent with EAFL, were isolated from the mares that aborted. Focal mucoid placentitis lesions were present on the placentas of 2 treated mares, one from each experiment.
Conclusions and potential relevance
Processionary caterpillar exposure may be associated with EAFL-related embryonic and early fetal loss in mares. Processionary caterpillars may also play a role in the occurrence of focal mucoid placentitis.