I was wondering if you could help me. For a friend, I look after a 15.3-hand mare who is six years old. The horse had a fairly bad start in life as she was first abandoned in a stable, then in a field. She has luxating patellas in both hind legs and gets distressed if left for long periods in a stable as her legs continually lock up. For this reason, she is field-kept almost all the time.

She was well broken in and accepts a rider and bit; however, if asked to ride out on her own, she plants herself and refuses to move, no matter what we try. She has even started doing this when riding out with one companion. For the last three years, she has been well cared for and hasn’t been mistreated, yet she still refuses to hack out alone. I accept that she is showing normal herd behavior, but is there any way we can convince her to go out for a ride with one companion? She will go willingly if she has two companions. Please help me as I am unsure of what to do, and I do not wish to cause her to become unridable.


Because of the patella issues, I have asked a colleague, Nancy Diehl, VMD, MS, to answer your question. Dr. Diehl was an equine veterinary practitioner for several years, and she is now on the faculty at Pennsylvania State University. She does research and teaches horse behavior in the university’s Equine Sciences program. She is especially qualified to answer your question. This is her reply.

Sue McDonnell, PhD, Certified AAB

When we hear of a horse performing an undesirable behavior, we usually look first to rule out any physical constraints that could reasonably cause or exacerbate the problem. Regarding your mare in particular, you give a history of locking patellas. This is not generally a painful condition; however, it is worth considering that this may be part of the problem. Any time a horse has a long-standing con