A survey of reproductive performance in Thoroughbred mares and morbidity, mortality and athletic potential of their foals.

This research study assessed the reproductive performance of Thoroughbred mares and the health, survival rate, and athletic potential of their foals during their first year of life. High rates of morbidity and mortality were observed amongst the foals, and those with health issues were more likely to be deemed physically unsuitable for athletic use.

Research Methods

The research was conducted via a survey involving Thoroughbred mares and their foals from four Western Canadian provinces. Identification of the owners was achieved through data from the North American Jockey Club, and questionnaires pertaining to mares bred in 1988 and their offspring born in 1989 were sent out. The surveys covered factors such as the mares’ reproductive performance and records of the foals’ health, survival, and athletic abilities.

Findings

• Eighty-three percent of the mares ended up being pregnant following breeding, and 80% of these pregnancies resulted in live births.
• Notable instances of morbidity and mortality were reported amongst the foals. One in four had health problems, and 5% died within two weeks of being born.
• Of the foals that survived the first two weeks, 27% had health issues between day 15 and their first birthday, and 6% died within this period.
• Foals with health complications within the first two weeks, or between fifteen days and one year old were five to seven times more likely to be regarded as physically unfit for athletic use.

Mortality and Morbidity Rates per Ailments

• The study showed that horses with upper respiratory infections and diarrhoea yielded much lower fatality rates than those with less frequent but infectious diseases.
• Mortality rates among horses with musculoskeletal issues were relatively high post the 2-week period.
• Angular limb deformity was the most commonly reported health problem among foals deemed physically unfit.
• Assessments of longterm athletic potential appeared to be unaffected by the occurrence of infectious diseases.

Significance of the Findings

This study is a crucial step in understanding the challenges faced in the breeding of Thoroughbred mares and the high mortality and morbidity rates amongst their foals. The findings draw attention to the major health issues affecting this breed and their impact on the athletic potential of the horses. The results could be used to guide future breeding programs and the management of foal health to improve breeding success rates and foal performance.