Influence of pituitary pars intermedia dysfunction on reproductive performance in Thoroughbred mares.

The research investigates the impact of an age-related disease known as Pituitary Pars Intermedia Dysfunction (PPID) on the fertility of Thoroughbred mares. The study, conducted across 137 farms in Japan, found a measurable connection between PPID and decreased pregnancy rates, particularly as mares age.

Goal of the Study

• The study aimed to understand the effects of Pituitary Pars Intermedia Dysfunction (PPID), a disorder often associated with ageing, on the fertility of Thoroughbred mares. The goal was to separate the impact of PPID on fertility from the natural effects of aging.

Methodology

• A total of 332 Thoroughbred mares aged between 10 and 20 years were included in the study. These mares were managed across 137 private farms in Hidaka, Hokkaido, Japan.
• The mares were classified into three groups based on their plasma adrenocorticotropic hormone concentration, these categories were: PPID, equivocal, or non-PPID.
• The researchers also studied the associations between PPID prevalence and age, as well as blood biochemistry parameters including prolactin levels.
• Through multivariable logistic regression analyses, adjustments were made for potentially confounding factors such as the mare’s age and PPID status to evaluate the impact on fertility.

Results

• The prevalence of PPID among the Thoroughbred mares was noted to be 9.04%.
• No significant differences in prolactin concentrations were observed among the different PPID status groups.
• The odds of a pregnancy decline associated with age were higher in PPID mares compared to non-PPID mares.
• Of the 30 PPID mares, 24 were divided into treated or untreated groups and monitored for pregnancy outcomes. The researchers found the treated group had a higher pregnancy rate than the untreated group.

Conclusion

• The study suggested that PPID negatively impacts fertility, particularly as the Thoroughbred mares get older.