A Studly Gelding

Q: I often joke that my gelding has a worse heat cycle than a mare. He's a 15-year-old off-the-track Thoroughbred (he was a stallion at least until he finished racing at age 6, but I'm not sure exactly when he was gelded) who is usually very mild-mannered, lives in a paddock by himself because he gets pushed around by other horses, and has always been very quiet around mares (even when they're in season).

This year he started displaying stallionlike behavior when the mares he's pastured next to came into season, at which point he began striking out when he was near them, vocalizing more often, becoming difficult to lead or work with, and pawing and kicking at his stall walls. Under saddle he wasn't able to focus on my aids whenever "his girls" would call for him. Just as suddenly as this behavior started, however, he went back to his old self when the mares were out of season. What could cause this behavior to develop so late in life? Is there anything I can do to combat it? Erica Lynn, Lexington, Ky.

A: Although fairly rare, emergence of stallionlike behavior in a long-time gelding can happen. In these cases it is good to try to rule out the possibility of a retained testicle or testicular remnant that might have started producing enough testosterone to drive stallionlike behavior. This is uncommon, but it is only fair to work with your veterinarian to rule that out with some hormone tests.

More often we conclude that changes in social situation (for example, a change in the number of other males or females, or pasture arrangements) likely provoke the emergence of the residual stallionlike behavior. Next spring you might try pasturing your horse away from mares if you can so he's less likely to adopt the fenceline "harem stallion" role.

About the Author

Sue McDonnell, PhD, Certified AAB

Sue M. McDonnell, PhD, is a certified applied animal behaviorist and the founding head of the equine behavior program at the University of Pennsylvania's School of Veterinary Medicine. She is also the author of numerous books and articles about horse behavior and management.

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