Study: Oxytocin Does Not Cause Cardiac Changes in Mares

This is good news, researchers say, since oxytocin infusion is the best treatment for retained placenta in mares.
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Study: Oxytocin Does Not Cause Cardiac Changes in Mares
“Parturition in the horse (and in all other mammals) is a very complex condition, and we still have a lot to learn,” Aurich said. | Photo: iStock
The hormone oxytocin is associated with foaling—it causes the mare’s uterus to contract, open the cervix, and push out the foal. However, unlike in humans, it doesn’t seem to cause the cardiac changes that occur during birth. And that, researchers say, could be reassuring news when a retained placenta requires oxytocin injections.

“Oxytocin infusion is the best treatment of retained placenta in the horse, and the present study shows that this method is safe with regard to cardiac function in horses,” said Christine Aurich, DVM, PhD, head of the Graf Lehndorff Institute in Neustadt, Germany.

In their study, Aurich and her fellow researchers injected 27 study mares with either oxytocin or saline, intravenously, in three stages: an hour after foaling, 12 hours after foaling, and seven days after the first post-foaling ovulation. They studied cardiac changes after the injections in these otherwise healthy mares to see what effects, if any, the drug (or saline control) had on the mares’ hearts and circulatory systems.

Blood parameters and electrocardiogram readings did not reveal any cause-effect relationship between oxytocin injections and cardiac changes, Aurich said. This is contrary to popular scientific belief that oxytocin causes these changes—likely due to the fact that cardiac changes do occur during labor and foaling, at the same time that oxytocin is released naturally. However, the current study suggests it’s not the oxytocin that’s responsible for those cardiac effects, but other phenomena relating to the birthing process

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Passionate about horses and science from the time she was riding her first Shetland Pony in Texas, Christa Lesté-Lasserre writes about scientific research that contributes to a better understanding of all equids. After undergrad studies in science, journalism, and literature, she received a master’s degree in creative writing. Now based in France, she aims to present the most fascinating aspect of equine science: the story it creates. Follow Lesté-Lasserre on Twitter @christalestelas.

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