Improving the odds: Pinpointing the key factors in Thoroughbred pregnancy loss
The Thoroughbred industry is on a mission to enhance its foal crop by understanding and addressing the causes of pregnancy loss in mares. This month, we delve into a multi-stage project led by AgriFutures Australia's Thoroughbred Program, focusing on the pathology and epidemiology of equine pregnancy loss. The project aims to uncover the factors contributing to pregnancy loss and their impact on the breeding industry, particularly in Queensland.
Understanding the Risks and Environmental Factors
Despite advancements in reproductive science, the percentage of live foals born from Thoroughbred mares has remained around 65% over the past five seasons. Breeding is a costly and time-consuming process, and reducing risk factors in the mare's environment is crucial. While the risks associated with birds, bats, and processionary caterpillars are well-known, the specific stage of pregnancy and environmental factors that expose mares to these risks vary by region.
In 2020, AgriFutures Australia's Thoroughbred Program initiated a comprehensive research project to investigate pregnancy losses in different areas of the country. The initial stage analyzed data from the Hunter Valley, aiming to identify the leading causes of pregnancy loss and their distribution. Dr. Joan Carrick, an equine specialist, led the project alongside Associate Professor Victoria Brookes from the University of Sydney, bringing over four decades of expertise in perinatal foal pathology and high-risk pregnancy management.
The study revealed that control mares were six times more likely to be vaccinated against salmonella, and a strong correlation existed between environmental factors in paddocks and rates of pregnancy loss. Dr. Carrick explained that the study collected detailed information about the paddocks, including tree types, pasture, water sources, and fencing. The research found significant differences in paddocks, with mares in less manicured central areas more likely to abort.
Mapping Trends and Expanding Research
The current study, which began in 2025, continues to examine these factors across the Hunter Valley and has expanded to include studs in Queensland. Dr. Carrick emphasizes the importance of repeating the research across Australia's diverse breeding regions, as little work has been done to understand losses in Queensland. She highlights that the trends observed will be unique to each region, and the study aims to build on previous findings.
The research team plans to collect data from the Hunter Valley and compare it year-on-year, analyzing patterns and trends. Dr. Carrick notes that understanding outbreak patterns over the last 25 years is crucial, as it helps identify factors that contribute to pregnancy loss. The goal is to formulate strategies to minimize identified risks and improve the ratio of covers to live foals born annually.
A Roadmap for the Future
AgriFutures Australia has released a resource package on preparing and managing mares during the abortion season. Dr. Carrick hopes that the research will assist more pregnancies to go to term, leading to healthier pregnancies and foals. By understanding the causes of losses, the industry can minimize factors contributing to them, even if some genetic influences cannot be altered.
The project's findings will provide valuable insights to breeders in Queensland, helping them understand the factors influencing pregnancy loss in their environment, the number of losses, and when they occur. This knowledge will enable breeders to allocate time and resources more effectively, ensuring every pregnancy is precious and healthy.
