Investigations into Causes of Equine Abortions and Perinatal Loss in Canada
Date
2024-08-21
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0001-6277-2530
Type
Thesis
Degree Level
Doctoral
Abstract
Around 20% of Equine Canada members surveyed identify themselves as horse breeders, making equine breeding a large component of the equestrian industry in Canada. Major sources of economic loss for horse breeders are equine abortion and early foal death, as both outcomes result in a wasted breeding year for the broodmare. However, investigations into causes of abortion and foal death in Canada are few. Our initial retrospective studies examined the most common causes of abortion and early foal loss across Canada, drawing on necropsy reports from the large provincial diagnostic labs. From these studies, we identified that umbilical cord torsions were very common in Canada, similar to findings out of the United Kingdom. In neonatal foals, noninfectious diseases as a group were more common than infectious diseases, however overall the most common cause of loss was bacterial infections, including septicemia. Looking into bacterial infections and abortions in horses identified a potential knowledge gap, as recent investigations into Chlamydia as a cause of equine abortion in Australia created questions regarding whether Chlamydia was a potential abortigenic agent in North America. We pursued this knowledge gap through performing PCR on archived formalin-fixed, paraffin-embedded equine chorioallantois tissues, and identified 22 PCR-positive cases of Chlamydia in 99 samples. We continued this research by investigating equine endometrial biopsies, identifying 40 PCR-positive cases in 98 samples. These findings collectively suggest that Chlamydia, specifically Chlamydia abortus, may have a significant role in equine abortion and infertility in Western Canada. Finally, we examined the potential role of umbilical cord torsions, the most common cause of abortion in Canada, in early neonatal health. Using data collected through social media from around the world, we identified that foals with longer umbilical cords or more twists in their umbilical cords had a higher risk of abnormal neonatal health outcomes, such as being slow to meet typical milestones. Affected foals were also more likely to require medical intervention at birth and more likely to develop an internal medicine-related condition between birth and 7 days of age. Overall, these studies provide additional insight into equine abortions and early foal loss, with an emphasis on these conditions in a Canadian context.
Description
Keywords
Equine, abortion, perinatal loss, equine reproduction
Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Western College of Veterinary Medicine
Program
Veterinary Pathology