Compulsive Circling

Q: I was wondering, why does my blind horse constantly pace in circles in an anticlockwise direction? He has been blind for about two years. I rescued him so I really do not know exactly how he became blind, as I am not getting a straight answer from anyone who knew him before me.

Elizabeth Bland, via e-mail

A: Circling is pretty typical of some blind horses, especially when kept in a small enclosure or stall, but they'll also travel in small circles within a larger paddock. Each blind horse I have known that does this circling behavior has consistently turned in the same direction; some always went clockwise and some always went counterclockwise. One was born without eyes, and his direction was always counterclockwise. He had a head tilt to the left as well. I can only remember about five or six blind horses in our care that we could say with certainty were completely blind in both eyes and had a tendency to circle, so it would be great if readers could let us know their experiences.

In the meantime, I shared your question with our ophthalmologist here at New Bolton Center, Mary Utter, DVM, PhD, Dipl. ACVO, as well as our equine neurologist, Amy Johnson, DVM, Dipl. ACVIM. According to Utter, the reasons for circling are more obvious if a horse is blind only in one eye. He might circle toward the blind eye to point the visual eye forward, or he might circle toward the visual eye to move toward the visual field--although the latter seems less likely.

"Regarding a bilaterally (in both eyes) blind horse, circling could be behavioral, associated with fear or anxiety in a more acutely blind horse (one that has become blind suddenly, not gradually), and then learned as time progresses, or an alternation in balance which results in a head tilt or postural change such that circling results," says Utter. "But persistent circling in a horse blind for over two years must be the former. Circling could be driven by persistent anxiety; another factor might be handling (e.g., does the owner always approach the horse on the same side?)."

"I can't think of a good neurologic explanation why (bilaterally) blind horses would always circle in the same direction, other than developing familiarity with surroundings and not wanting to deviate from the learned path," says Johnson. "I might mention that horses with intracranial (inside the skull) disease can manifest both blindness and compulsive ¬circling as signs. However, if this horse truly had a brain problem significant enough to cause both cortical (central) blindness and compulsive circling, I would expect that the owner/veterinarian would detect other neurologic signs or signs would have progressed over a period of two years."

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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