Research: Australian Caterpillars and Equine Fetal Loss

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Credit: DAFF Archive, Bugwood.org Processionary caterpillar.

Credit: DAFF Archive, Bugwood.org Processionary caterpillar.

The United States wasn’t the only country to have experienced fetal loss thought to have been triggered by pregnant mares consuming various species of caterpillars. Research from Australia has been published in Veterinary Pathology that offers another link to caterpillar-induced fetal loss in horses.

You can find more information about “Processionary Caterpillar Setae and Equine Fetal Loss; Histopathology of Experimentally Exposed Pregnant Mares” on Sagepub.com.

Abstract

“Six pregnant Standardbred mares aged between 6 and 14 years were gavaged with 50g or 100g of suspended emulsified whole Processionary caterpillars (Ochrogaster lunifer) for 5 days during 2 experiments undertaken to study the etiology of equine amnionitis and fetal loss (EAFL). The 6 treated mares and 1 untreated mare were between 128 and 252 days gestation. Mare 1 (untreated) was euthanized on Day 5 of the treatment period, while the treated mares were euthanized on Days 2, 4, 8, 10, 12, and 24 days from their first treatment. Caterpillar setae were not found in the untreated mare. Setal fragments were present in all regions of the gastrointestinal tracts in all treated mares, the uteri and mesenteric lymph nodes of 5 mares, and the liver of 4 mares. Acute gastroenteritis of varying severity was present in all treated mares, and 5 of 6 mares had acute colitis and endometritis. Focal hyperplastic serositis was found in the duodenum, cecum, dorsal colon, and uteri of various mares occasionally with embedded setal fragments. Setal invasion of the mucosa evoked a range of lesions including superficial erosion to deep ulceration. Inflammation in deeper tissues ranged from unapparent to neutrophilic (microabscesses), eosinophilic, or mononuclear (microgranulomas). The finding of setal fragments within the uterus of experimental mares suggests that direct migration of setal fragments acting as a bacterial vector is a likely mechanism for the bacterial abortions that characterize equine amnionitis and fetal loss.”

Authors

K. H. Todhunter, Equine Research Unit, School of Agriculture and Food Sciences, The University of Queensland, Gatton Queensland, Australia

A. J. Cawdell-Smith, Equine Research Unit, School of Agriculture and Food Sciences, The University of Queensland, Gatton Queensland, Australia

W. L. Bryden, Equine Research Unit, School of Agriculture and Food Sciences, The University of Queensland, Gatton Queensland, Australia

N. R. Perkins, Equine Research Unit, School of Agriculture and Food Sciences, The University of Queensland, Gatton Queensland, Australia; AusVet Animal Health Services, Toowoomba, Queensland

A. P. Begg, Vetnostics, North Ryde, New South Wales, Australia