Is your mare behaving more (night)marish lately, or is your gelding acting studly? Before recruiting a behaviorist or administering medication, experts advise ruling out medical issues for any animal experiencing behavior problems.

"A number of conditions can cause hormonal imbalances in horses of either sex that affects their behavior," said Barry A. Ball, DVM, PhD, Dip. ACT, the Albert G. Clay Endowed Chair in Equine Reproduction at the University of Kentucky’s Maxwell H. Gluck Equine Research Center.

The problem with diagnosing hormonal imbalances is that many tests are not accurate or sensitive enough to detect small changes in blood levels of certain hormones. Also, many hormone levels fluctuate (in a cyclic manner), depending on time of day and/or season. To date, practitioners have used testosterone, inhibin, progesterone, and estrogenlike hormones to help diagnose ovarian tumors in mares and/or cryptorchidism (undescended testicles).

"Inhibin and testosterone are not ideal because both may be elevated normally during pregnancy in the mare, and pregnancy must be excluded in order to interpret their values," Ball said