The use of prostaglandin F2alpha in controlling the oestrous cycle of the mare and steroid changes in the peripheral blood.

This research investigates the impact of Prostaglandin F2alpha on inducing the oestrus cycle and ovulation in non-cyclic mares, with a successful response rate of 80% or more. The study also explores the effects on steroid hormone levels and its potential use in treatment of severe endometritis.

Inducing Oestrus and Ovulation in Non-Cyclic Mares

• The investigators used Prostaglandin F2alpha (PGF2alpha), a hormone-like substance, to induce the oestrus cycle and ovulation in female horses (mares) that were not currently going through their reproductive cycles.
• This substance was delivered to the mares through two methods: untrauterine infusion (directly to the uterus) and intramuscular injection (into the muscle).
• The result showed that over 80% of the mares responded positively to this treatment, entering the oestrus cycle and reaching ovulation. This high response rate was consistent regardless of the method of delivery used.
• The dose of PGF2alpha used ranged from 2.5 to 7.5 milligrams, and the time taken for ovulation to occur was up to 9 days, regardless of the delivery route.

Conception and Steroid Hormone Levels

• Although the oestrus induction was successful, only about half of the mares conceived after mating during the induced oestrus cycle. The researchers believe this may be due to infertility issues amongst the mares tested.
• The levels of progesterone, a hormone that prepares the uterus for pregnancy, remained at basal levels following the PGF2alpha administration, indicating that the artificial induction of oestrus did not drastically impact progesterone levels.
• Oestrogen levels, a hormone that is crucial for the reproductive and menstrual cycles, were inconsistent, showing no clear trend after administration of PGF2alpha.

Additional Observations and Implications

• The researchers experienced some success using PGF2alpha to treat severe endometritis (inflammation of the inner lining of the uterus) in one mare, indicating potential therapeutic uses beyond cycle and ovulation induction.
• This research suggests that PGF2alpha could potentially be a useful tool in equine reproductive management, particularly for inducing the oestrus cycle and ovulation in mares not currently in their cycle.