As spring approaches many animals begin to display signs of sexual activity. The drive to reproduce dominates the minds of many animals however it can cause problems for our equine friends and their paddock mates. It is common to hear reports that an otherwise friendly gelding has started to herd his paddock mates, show aggression towards other geldings and display signs of sexual arousal towards mares. This can sometimes cause issues in herds or at public agistment facilities and can cause confusion and worry for owners.

False Rigs

Continued stallion-like behaviour can be a complication of castration. Geldings that display stallion-like behaviour are sometimes called false rigs. False rigs may display masculine behaviour ranging from genital investigation and squealing to mounting and even copulating. False rigs are often said to be proud cut, indicating that some epididymal tissue was left with the horse at the time of castration. Only if testicular tissue remained would stallion-like behaviour be the result of incomplete castration.

Quite a few completely castrated geldings with normally low steroid hormones continue to show stallion-like behaviour, particularly under social pasture conditions. While estimates vary, it has been estimated that almost 50% of geldings continue to show considerable residual stallion-like behaviour.

Because some sexually experienced stallions castrated late in life continue to display masculine behaviour, stallion-like behaviour in geldings has been attributed to learned behaviour. One study found no difference in the prevalence of stallion-like behaviour between horses castrated before puberty and those castrated after puberty.

Changes in management or stricter discipline may alleviate sexual behaviour or reduce it to a tolerable level.

What can you do for your gelding?

You can consider manipulating his social housing conditions to minimise the behaviour and/or the resulting problems. For example, you can house him away from other horses all together. Geldings eventually quiet down after prolonged separation from their “herd.” You might consider trying to take advantage of natural social suppression of stallion-like behaviour by housing your gelding within reasonable proximity to one or more stallions. Most geldings become socially submissive to stallions, and will appear to become demoted to the rank of immature male or bachelor stallion.

If the conservative method does not give your gelding relief, he should be tested for the possibility of remaining testicular tissue.  This is a small blood test which can be done in geldings older than 3 years of age in an attempt to rule out a cryptorchid or incomplete castration. If you wish to arrange for your gelding to be test please feel welcome to make an appointment.

Alternative methods

Regumate is the female hormone progesterone used in behaviour modification in mares, geldings and stallions.  The administration of female hormones such as progesterone, appear to somewhat subdue stallion-like behaviour. It can be effective in quieting a stallion or gelding for show or working situations however it is not effective for a gelding or stallion for long term social pasture situations.