Q. I have four horses, and each stays in its own stall with a 36-foot-long sand run. All rear stall doors are left open 24/7. Three of the horses always walk to the far end of their runs to urinate and defecate, leaving their stalls nice and clean. However, a mare I purchased last year does just the opposite—she returns to her stall to urinate and defecate, causing enormous additional work and mess. I have tried all manner of behavioral modification (positive and negative), such as keeping her stall very clean and the “tough love” approach of leaving her manure and urine for several days. I’ve tried putting other horses’ manure in her run; putting shavings in her run; and banging on the stall bars when I can catch her. So far, nothing has worked. Can you offer any other suggestions?

C. Bender, Boulder, Colo.

A. If your three horses that always go out to the edge of their runs are geldings, the answer is easy. Stallions tend to be organized about their defecation and urination, and when confined they tend to defecate at boundary points as if “marking” significant boundaries or resources. Geldings retain this stallion behavior to varying degrees. Mares, on the other hand, tend to urinate and defecate in their environment at random. Occasionally you find a mare that defecates mostly in the same place, but this behavior isn’t as common in geldings.

I am not surprised that your efforts to modify the mare’s behavior have been ineffective. I am sure the mare has no idea what you are trying to get her to do. Theoretically, you could train a horse so as to increase its likelihood of urinating or defecating in a particular spot, but it takes a lot of patience. The general strategy would be to wait for the horse to reach the spot and immediately (while they are voiding) provide primary positive reinforcement (something innately satisfying such as a food treat) or well-established secondary reinforcement (something that has been established as paired with primary positive reinforcement).

The desired response with the well-timed positive reinforcement has to happen repeatedly in fairly rapid succession for the horse to make the connection with the location. I have talked to several people who have tried to do this with horses and have failed. For those whose objective was the same as yours—to reduce the soiling of the stall or to reduce barn cleaning chores—in the end they concluded it was easier to just clean the stalls.

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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