Exposure of mares to processionary caterpillars (Ochrogaster lunifer) in early pregnancy: an additional dimension to equine amnionitis and fetal loss.
Authors: Cawdell-Smith A J, Todhunter K H, Perkins N R, Bryden W L
Journal: Equine veterinary journal
Summary
# Editorial Summary Equine amnionitis and fetal loss (EAFL) remains a significant reproductive challenge in Australian mares, characterised by mid- to late-gestation abortion with distinctive pathological features that have confounded diagnosis and prevention since first documentation in 2004. Cawdell-Smith and colleagues investigated whether exposure to the processionary caterpillar *Ochrogaster lunifer*—both living specimens and shed exoskeletons—could trigger EAFL-type abortions, using controlled experimental exposure during early pregnancy. Both intact caterpillars and their discarded exoskeletons successfully induced abortion in exposed mares, with resulting gross pathological and bacteriological findings matching those observed in naturally occurring field cases of EAFL. This work significantly expands our understanding of EAFL aetiology beyond previously identified causes and establishes a clear environmental toxin link, suggesting that practitioners in affected regions should incorporate caterpillar exposure history into reproductive risk assessment and consider implementing grazing management strategies to minimise mare contact with these arthropods during critical periods of gestation. The findings also indicate that passive exposure through shed exoskeletons—which may persist in pasture environments—poses an underestimated hazard requiring further investigation into seasonal occurrence patterns and contamination persistence.
Read the full abstract on PubMed
Practical Takeaways
- •Avoid exposing mares to processionary caterpillars and their shed exoskeletons during early pregnancy to prevent abortion
- •Recognize that EAFL may present with pathological findings consistent with processionary caterpillar-induced abortion, warranting investigation of environmental exposures
- •Monitor mares in regions where Ochrogaster lunifer is present during breeding season, particularly in early gestation
Key Findings
- •Both whole processionary caterpillars (Ochrogaster lunifer) and their shed exoskeletons can induce abortion in mares during midgestation
- •Abortions induced by caterpillar exposure exhibited gross pathology and bacteriology results consistent with field cases of EAFL
- •EAFL is an unusual form of abortion first identified in Australia in 2004, with caterpillar exposure identified as a causative factor