The effects of perphenazine and bromocriptine on follicular dynamics and endocrine profiles in anestrous pony mares.

This study investigates the effect of two drugs, perphenazine and bromocriptine, on the reproductive cycles of non-breeding female ponies. The researchers found that altering prolactin levels with these drugs could advance or delay ovulation, without affecting the overall fertility of the animals.

Study Design and Procedure

• The study involved 19 female ponies that were not currently breeding.
• The ponies were divided into three groups and given different treatments. Group A received perphenazine, a dopamine antagonist; Group B received bromocriptine, a dopamine agonist; and Group C received a salt water (saline) injection as a control.
• All treatments were started on January 20, 1994, and continued until the ponies ovulated. The ponies’ behaviour was regularly observed in relation to a male pony.
• The overall health and reproductive state of the ponies was assessed with physical examinations and ultrasound images.

Data Collection and Results

• By monitoring the ponies’ ovaries, the researchers observed when the ponies entered the reproductive phase (estrual behavior) and the growth of the follicles.
• Blood samples were taken from each pony to measure levels of hormones including prolactin, FSH and Estradiol-17 beta.
• The treatment with perphenazine (Group A) caused the ponies to enter the reproductive phase earlier and develop larger follicles sooner than the control group.
• The ponies in Group B, treated with bromocriptine, developed larger follicles later than Group A.
• The ponies in the control group (Group C) developed follicles at a time between Group A and Group B.
• The bromocriptine treatment led to decreased prolactin levels throughout the study, while perphenazine did not have a significant overall effect. However, perphenazine did cause increased average prolactin concentrations from day 31 to 60 of the treatment.

Conclusion of the Study

• From these results, the researchers concluded that altering the ponies’ prolactin levels using perphenazine and bromocriptine can influence when the ponies ovulate.
• The perphenazine treatment seemed to speed up the process of follicle growth and ovulation, while the bromocriptine treatment seemed to slow it down. However, neither treatment affected the ponies’ overall fertility levels.
• The findings of this study could potentially have implications for managing the breeding and non-breeding phases of ponies and possibly other animals.