Question: I keep hearing about self-mutilation in stallions, but I’ve never actually seen it. Can you tell me more about it?

Answer:

Is self-mutilation only performed in stallions?

Self-mutilation can be observed in stallions, geldings or mares, and is also seen in species other than horses, including dogs and cats (paw and tail chewing) and humans (pulling out hair, scratching oneself, skin picking, biting of the tongue, lips, or nails, deliberate infliction of cuts, burns, bruises, and other wounds), and others.

 What is self-mutilation?

Self-mutilation in stallions is an oral stereotypie that often occurs (or begins) between the ages of 2 and 4 years of age. The stallion will bite and kick at his belly, ribs and flanks. While biting is the most commonly seen behavior in what is sometimes also called flank biting or sucking, a cluster of behaviors form what is aptly called self-mutilation. Some stallions will spin in tight circles and squeal while performing the behavior. The stallion may buck, kick one or both legs, lunge against a wall, or even throw themselves to the ground during an episode of self-mutilation. He may bite or nip at his chest, sides, flanks, or abdomen. An episode may last for a few seconds to several minutes, or may be performed at intervals over a period of hours. These behaviors could result in injury and there are often tell-tale wet marks, bumps, missing hairs, or the appearance of hairs that have been chopped off bluntly (they’ve been bitten off).

How common is self mutilating behavior?

It is estimated that fewer than 0.01% of horses perform self-mutilation. Long term observation (such as by video-recording) of suspected self-mutilators can help determine how frequently and intensely the animal is performing the behaviors. Certain breeds appear to be more likely to exhibit the cluster of behaviors defined as self-mutilation, particularly Arabians, Quarter Horses, and Standardbreds.

What causes self-mutilation behavior? 

Some horses have an explosive, violent reaction to pain, and may be performing self-mutilation in response to pain such as that from colic, foaling, abdominal abscesses, gastric ulcers, twisted testicular cords, kidney stones, or other illnesses or injuries. Increased stress due to training, showing, or introduction to breeding may trigger the behavior. Other triggers may include the anticipation of feeding, the presences of other horses or their urine or feces, or even changes in the weather.

How can self-mutilation be eliminated?

Temporary Fixes:

Physical restraints, such as neck cradles, muzzles, shock collars, and protective wraps or blankets, are sometimes used to help protect the horse, although preventing certain behaviors (such as biting) may evoke even more violent behaviors (such as lunging against the wall or throwing himself to the ground). Others have found keeping the horse in a tie stall rather than a box stall eliminates the behavior. Drugs, including long term tranquilizers, tricyclic anti-depressants, and even the feed supplement L-tryptophan have been reported to decrease self mutilating behavior, but can be costly and should be considered a temporary fix.

Long term management:

If pain is the source of the behavior, treating the issue will often resolve the behavior. If the behavior continues following treatment of a physical ailment, other behavior modification options may be explored.

If self-mutilating behavior is caused by a factor other than pain, there are several options that may help eliminate the behavior. Sometimes a horse will perform the behavior out of boredom, and simply increasing the horse’s turnout time or increasing the horse’s working time will eliminate or significantly decrease self-mutilation.

Adding a stall mate or pasture companion, such as a chicken, goat, sheep, or pig may appease the self-injurious animal. Isolation is not a natural situation for a horse, although some horses perform self-mutilation only in the presence of other horses. In this instance, eliminating other stallions (or other horses) from the vicinity of the individual performing the behavior may be necessary.

Diet changes may also eliminate the behavior. Decreasing the grain ration and increasing the forage ration may cause the horse to spend more time consuming forage and allow less time for the performance of undesirable behaviors. This option is often combined with increased turnout or exercise.

Castration may be suggested, and may work very well or may have no effect. Some horses do not begin to self mutilate until after they’ve been castrated.

Ultimately, the goal is complete cessation of self mutilation, although this is not always possible. Care should be taken when handling animals that are apt to self-mutilation as changes to their schedules may increase the frequency of the behaviors. It has also been suggested that horses that perform self-mutilation are more likely to perform other undesirable behaviors that may cause handler injury.