Oxytocin treatment does not change cardiovascular parameters, hematology and plasma electrolytes in parturient horse mares.

This study investigated whether oxytocin, a hormone associated with childbirth and nurturing behaviors, causes changes in various cardiovascular and blood measurements in horse mares after giving birth. The findings demonstrate that, other than a slight impact on cortisol release, oxytocin treatment does not significantly alter heart rate, blood pressure, blood count, or plasma electrolytes in these animals.

Objective of the Research

• The research aimed to examine the effects of oxytocin on cardiovascular parameters, hematology, and plasma electrolytes in horse mares after foaling.
• This stemmed from the hypothesis that these changes observed after giving birth could be induced by the hormone oxytocin.

Research Setup and Results

• Three tests were conducted at different stages: one hour after foaling (test A), twelve hours after foaling (test B), and during the first postpartum diestrus (test C).
• Mares were either treated with oxytocin or with a saline solution as a control.
• The researchers observed a decrease in heart rate from test A to test C, but it highlighted no major difference between the oxytocin and control groups.
• The study found that heart rate variability, blood pressure, and the incidence of atrioventricular blocks did not respond to oxytocin treatment.
• While cortisol concentration decreased from test A to C, oxytocin triggered a cortisol surge during test B.
• They noted a decrease in plasma sodium and chloride concentrations from test A to C, with no discernible differences between the groups. In contrast, potassium concentration increased in the control group during test A, but not in the oxytocin group.
• There was a decrease in polymorphonuclear (PMN) cell numbers in the blood from test A to C and an increase in lymphocytes, but no difference between the groups.

Conclusion of the Research

• Overall, oxytocin treatment had little effect on the cardiovascular parameters, plasma electrolytes, and hematology of horse mares, other than a short-term effect on cortisol release.
• This effectively refutes the hypothesis that oxytocin causes significant alterations in these parameters in postpartum horse mares.