Problematic Behavior in Nonpregnant Mares: Is it Reproduction-Related?

Vets should perform a careful assessment of a mare’s hormonal status to determine whether there’s a definitive, repeatable relationship between it and her undesirable behavior.

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During diestrus, high progesterone levels generally trigger behaviors such as agitated movement, tail-swishing, ear-pinning and tense facial muscles, urine-squirting, aggression, and vocalization toward stallions. | Photo: iStock

Reproductive behavior in sport horse mares can range from annoying to performance-limiting. For this reason, many mare owners and their veterinarians try to control or eliminate it. However, how do you really know if her reproductive system is to blame?

Dirk Vanderwall, DVM, PhD, Dipl. ACT, set out to address this concern and offer ways to manage undesirable behavior in his presentation at the 2017 American Association of Equine Practitioners convention, held Nov. 17-21 in San Antonio, Texas. Vanderwall is a professor of horse reproduction at Utah State University’s School of Veterinary Medicine, in Logan.

At the start of his presentation, he polled the veterinary audience and found that 79% believed that estrous behavior affects some mares’ performance. These results were similar to those from a survey of more than 750 veterinarians in which 90% believed the estrous cycle affects mares’ performance

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Alexandra Beckstett, a native of Houston, Texas, is a lifelong horse owner who has shown successfully on the national hunter/jumper circuit and dabbled in hunter breeding. After graduating from Duke University, she joined Blood-Horse Publications as assistant editor of its book division, Eclipse Press, before joining The Horse. She was the managing editor of The Horse for nearly 14 years and is now editorial director of EquiManagement and My New Horse, sister publications of The Horse.

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