The effect of administration of a beta blocker in periparturient mares.

The research examines the impact of using a beta blocker, specifically propranolol, on the birthing process and fertility in horses. Propranolol was found to speed up removal of fetal membranes in mares and improved pregnancy rates in the subsequent heat period.

Study Design and Participants

• This experiment included 330 mares which were randomly divided into two groups – an experimental group and a control group.
• The experimental group consisted of 150 mares which were treated with propranolol during the second stage of labor. The dosage given was 50 mg administered through intravenous injection.
• The control group was composed of 180 mares which were not subjected to any specific treatment.

Measurements and Findings

• Various parameters were observed and recorded to assess the effect of propranolol on the mares. Primarily, the researchers monitored the time taken for expulsion of fetal membranes, occurrence of the next estrus (foal heat), and the resultant pregnancy rates following this heat.
• The use of propranolol appeared to greatly hasten the expulsion of fetal membranes. This is potentially beneficial as it may help prevent complications associated with retained fetal membranes, such as infection or inflammation.
• The researchers noted that the treated mares exhibited foal heat sooner than the untreated mares. Foal heat refers to the first estrus cycle that a mare goes through following childbirth. Quick return to estrus could be useful for breeding purposes.
• The pregnancy rates observed at the post-partum heat period were also higher for mares that were treated with propranolol. This suggests that propranolol may have a positive effect on the fertility of mares.

Implications of the Findings

• The healthcare of mares during and after childbirth can significantly influence both the well-being of the mares and the success of breeding practices. The expedited expulsion of fetal membranes seen with propranolol administration might serve to minimize potential post-partum complications in mares.
• The accelerated return to estrus and accompanying rise in pregnancy rates for the mares treated with propranolol signals a potential enhancement in breeding efficiency. As such, propranolol could offer substantial benefits for breeding programs and horse population management.