Effect of contextually congruent stallion vocalization playback on intrauterine pressure in the mare

Abstract

Although oxytocin can be an effective treatment for persistent mating-induced endometritis (PMIE), frequent administration is required due to the short half-life of oxytocin and exogenous oxytocin may produce tetanic spasms of the myometrium. Teasing with a stallion during estrus elicits endogenous oxytocin secretion and uterine contractions, which may result in a more optimum physiologic response. Recently, it has been shown that mares will respond to contextually congruent stallion vocalization recordings with teasing behavior. The aim of this study was to determine if contextually congruent stallion vocalization would induce uterine contractions and increased uterine pressure in the mare. We hypothesized that teasing, contextually congruent stallion vocalization (with or without stallion scent), and exogenous oxytocin would increase intrauterine pressure in estrous pony mares, but that oxytocin would cause the greatest increases in intrauterine pressure. Changes in uterine pressure were recorded using a wireless telemetry capsule inserted into the uterine lumen (SmartPill pH.p Capsule), a novel method of instrumentation for uterine pressure studies. Twentyfour hours after administration of human chorionic gonadotropin, five reproductively normal pony mares were instrumented with an intrauterine telemetry pressure capsule during estrus. Baseline pressure was recorded for