Chapter 4 STALLION SEXUAL BEHAVIOR
This chapter reviews normal and abnormal breeding behavior of domestic stallions. Included are practical considerations for routine management of stallions as well as for the retraining of behaviorally challenging stallions.
Descriptions of reproductive behavior of equids under free-running conditions are available in a number of resources.1,2 These can be very instructive toward understanding the basic nature of stallions and how behavior varies under domestic breeding conditions.
Most domestic stallions are handled under halter for live breeding or collection of semen. Compared with the full complement of harem formation and maintenance behaviors typical of a harem stallion under free-running conditions, the behavior of a domestic stallion bred under halter is typically limited to the immediate precopulatory interactions. Key elements of normal stallion behavior are listed in Box 4-1. To the extent allowed, these may include vocalization to the female, limited olfactory and tactile investigation, and flehmen response. Most stallions interact with an estrous mare as soon as allowed, achieve erection within 2 minutes of contact, and are ready to mount a receptive mare or dummy mount within 5–10 seconds after erection is achieved. Copulatory behavior of stallions includes mounting, insertion, thrusting, ejaculation, and dismount. Once mounting occurs, copulatory behavior of halter-bred stallions proceeds similarly to that of free-running stallions of any of the equid species. Most stallions ejaculate after six to eight organized pelvic thrusts. For most stallions on well-managed breeding farms, the entire breeding process, including washing of the penis, is usually accomplished in 1–2 minutes. With consistent good handling and a good stimulus mare, most stallions are remarkably consistent over time in their breeding behavior. Monitoring of the details of a stallion’s typical breeding behavior can be useful in early detection of problems. The most useful aspects to monitor include erection latency, number of mounts, thrusts, and palpable ejaculatory pulses. On many farms, live cover breedings or semen collections are videotaped, which provides a valuable record in case behavior problems arise.
Most stallions quickly learn the breeding routine to which they are exposed. They respond to conditioned stimuli associated with the breeding process, and they may breed efficiently with little or no teasing or contact with a mare. Others, still quite normal, may require considerable opportunity to interact with mares to become aroused. Some stallions that are bred under rigid protocols can appear to become “ritual-bound.” Any change in breeding routine may appear to disturb their response, usually temporarily. With patience and good handling, most ritual-bound stallions can usually adapt to procedural changes, even after years of a fixed regimen. Once these horses accept a new routine, occasional minor changes in routine can be useful in teaching the horse to be more flexible. In contrast to the ritual-bound stallion, some stallions tend to get “bored” with fixed breeding routines and clearly benefit from reasonable variety in breeding-stimulus mares, breeding location, handlers, and order of procedures. In extreme cases, stallions seem to need something new every few days to sustain their interest.
The handling of stallions for breeding is an art. Box 4-2 summarizes the important characteristics of good stallion handling, as well as common errors. It is also helpful to have a designated breeding area that is out of the way of farm traffic and that has plenty of room for both the animals and the personnel. In many cases of stallion-handling difficulties, human fear of the stallion, in general or specifically during breeding, is the primary challenge to overcome. Schooling for handling tough horses is probably the best way to become an excellent stallion handler, so such a situation is a good opportunity for development.
Almost all stallions are capable of learning the few basics of handling and manipulation required for organized, safe in-hand breeding or semen collection. These include maintaining attention to the handler, taking necessary direction from the handler during teasing, being tolerant of genital manipulation and washing of the penis, waiting for direction from the handler to mount, and maintaining orderly mount and dismount. Behaviors that are unacceptable and unsafe and that can be easily eliminated include biting or kicking of the mare or handler and rushing or charging to mount the mare. All of these goals can be achieved in any stallion with thoughtful arrangement of the breeding situation, positive reinforcement for desirable responses, and judicious direction and correction. Harsh beating, explosive disciplinary sessions, overcorrecting at the head, and jerking and shanking to hold the horse’s attention are all unnecessary, usually delaying the learning process. For some stallions, such handling can create serious behavior and libido problems.
Box 4-3 outlines the steps used at our clinic to introduce stallions to washing of the penis. Even for stallions that initially appear most resentful of manipulation, training to tolerate washing can be done safely within a short period (usually two to three 5-minute sessions) using simple positive reinforcement for increasing tolerance. The horse needs to learn as quickly as possible that this procedure does not hurt, that it may even be pleasant, and that avoidance will not interrupt procedure. Safe positioning of the handler and technician so that the work can proceed quickly and so that the technician can stay with the horse through episodes of mild resistance can greatly facilitate the process. Beyond the breeding hygiene reasons, the lessons of waiting for a procedure before breeding as well as tolerating genital manipulation and examination are valuable basic training for a stallion.
The handler of the stallion positions the stallion to stand under control, for example, parallel to a padded wall. The stallion handler stands on the near side almost in front of the stallion, but out of the way of a strike.
The washing technician approaches at the shoulder of the stallion, running the back of the left hand along the neck, shoulder and abdomen of the horse until standing with the left shoulder of the technician touching the side of the stallion. The erect penis is firmly grasped with the left hand midway along the shaft. It is gently directed toward the handler.
If the stallion moves away, the technician should attempt to move with the horse, without flinching or otherwise reacting. The stallion needs to learn two things: (a) The procedure is not going to hurt him (it actually quickly appears pleasant to most stallions), and (b) nothing the stallion does will avoid the procedure. In other words, his movement does not stop the washing of the penis.
If the stallion kicks, explosive punishment should be avoided. Gentle discouragement and continuation of the job so that the stallion gets to know that it can be pleasant and that it leads to the opportunity to breed is usually the best strategy for all but the most dangerously resistant stallions.
If the stallion should thrust forward or the glans penis should flower from the stimulation, no discipline is necessary. Gently deflecting the penis downward toward the back legs naturally reduces the tumescence. Cooler wash water is less likely to stimulate thrusting or flowering. It is useful for most handlers to appreciate that the horse is not misbehaving, just responding positively to this unnatural procedure.
All that is necessary to adequately cleanse the penis is gentle massage along the shaft to loosen flaky debris, with warm water splashed from a cup or towel onto the penis. Up and down stroking motion abrades the surface and is unnecessary.
Some horses resent having hot water splashed on their hind legs or abdomen and scrotum. With experience most technicians can effectively deliver a vigorous splash of water to the penis without hitting the belly or legs.