Rushing a Mare During Breeding

Q. I'm a veterinarian asking this question on behalf of clients who are standing a stallion at stud.  The stallion isn't new to breeding or to this farm; he's in his third or fourth breeding season. He normally breeds eagerly, without hesitation. Recently, he's been doing something unusual just with one particular mare. He seems interested in this mare but rushes right up and mounts her before he's ready (gets an erection).  They pull him off, and he does the same thing again. If they take him to another mare, he proceeds as usual--teases, gets an erection, and waits for the handler to signal him to mount.  They asked me what might be causing his rushing of this one mare and what they should do about it.

Via e-mail

A. What great questions! Mounting without erection happens more frequently with novice breeding stallions and is more often a general response rather than specific to one mare. But I have seen exactly what you describe in experienced breeders --mostly in stallions with the wisdom of pasture breeding experience. Yours just happens to be the third similar question on this topic in a couple of weeks, so we'll answer this one here in the column.

My first recommendation would be to convey the information that mounting without erection is a very normal part of the natural breeding behavior of equids--zebra, wild asses and donkeys, wild horses, and pasture breeding horses. In fact, observations of all these species indicate that under natural field breeding conditions, stallions mount twice on average without an erection to every mount with an erection. Under natural breeding conditions, mounting without an erection is the rule rather than the exception, most likely because as estrus progresses, most mares go through stages where we would interpret their behavior as "Yes, yes, yes, yes, please, oh please, NO WAY!"A plausible explanation is that a mount without an erection is a test of true receptivity of the mare --will she stand, or at the critical moment of vulnerability, will she let fly? This is just like the chin-resting response and "false mounts"in bulls; mounting without an erection is likely highly adaptive.  We wonder whether it is instinctive or learned.  As with almost everything else, it probably is a combination of the two.

In the case of your client's stallion, who is doing this with only one particular mare, my guess would be that he is especially uncertain about her readiness to stand for breeding.  Since he only mounts other mares when he is ready and signaled by the handler to proceed, he has likely become conditioned as a domestic stallion to take direction from the handler to "get ready,"and to wait until the handler allows mounting. But with this mare, he must be getting some worrisome "No,""Maybe,"or "Not Sure"signals from the mare. Understanding this possible interpretation usually helps handlers and managers appreciate that this stallion is probably especially smart rather than confused or stupid.  This knowledge alone usually helps everyone relax a bit and proceed positively to get the job done.

So what can be done? Even though it's normal stallion behavior to mount without an erection under natural field breeding conditions, for good reason we typically don't want to have stallions mounting again and again in the confines of the breeding shed. With a novice stallion that is doing this with every mare, the recommendation would be to get a good, reliable, and generous mount mare to let the stallion mount a few times undisciplined by the mare or handler. Once no disaster happens when he mounts without an erection, he usually proceeds with an erection.  This positive experience usually increases his confidence, enthusiasm, and willingness to take direction from handlers that it will be okay.

Next, what should they do about this stallion mounting just this mare without an erection? First of all, you need to make sure the mare is really ready to stand. If possible, have her mounted by a teaser (a stallion trained to "test mount"mares). Then once you're as sure as possible she won't explode when the stallion mounts, one approach would be to let the stallion and this mare get acquainted in side-by-side stalls or paddocks with a safe barrier.  Watch how things go and wait until you see the stallion getting an erection and hopping up as if ready to mount when teasing her.  You can assume he has made the decision that she is indeed ready to tolerate breeding.  Then bring the two together for hand breeding, or if conditions permit, just open the gate between the paddocks and let them breed unhandled. Large, obstacle-free paddocks will reduce the likelihood of injury.

Another approach is to get an expert handler who has experience with cases like this. Certain handlers can carefully and patiently hold the stallion back without invoking undue discipline that is counterproductive.  Their calm and judicious handling can convey confidence and trust to some stallions.  They are able to maintain control and attention of the stallion for close-up teasing, including leaning into the mare or nipping at her flanks and hocks as an alternate "test,"without injudicious jerking or discouraging discipline. Expert handlers of this type can also safely allow a stallion to mount without an erection, if necessary, or safely and gracefully handle the situation should the stallion get ahead of the handler and mount without an erection.

In this situation it also helps to let the mare naturally show her receptivity. For example, when a mare turns her head back and flexes one foreleg on her own, this seems to be a powerful sign to the stallion that she "isn't going anywhere"and will stand for mounting.  To the extent that this can be safely allowed, reducing mare restraint to enable a display of these responses might be just enough to convey trust of the stallion that the mare is ready. In recommending these procedures for any particular case, we would consider the facilities, skills, and experience of the staff as well as the temperament and behavioral history of the particular mare and stallion.

If these handling and management steps are not leading to satisfactory progress, anti-anxiety medication might be useful to the stallion. Benzodiazepines at low doses can be useful.  This class of drugs probably works in such situations by reducing anxiety and by releasing innate sexual drive. Most research and clinical work with benzodiazepines in breeding stallions have been with diazepam, which is a controlled drug that must be administered and monitored by a veterinarian.  And, in many cases, treatment with diazepam releases innate aggression as well as sexual drive.  So the handling team should be informed and prepared for increased aggression that might be counterproductive. Fortunately, in many cases diazepam works well and can be used as a short-term training tool.  Typically, it is only needed once or twice before the stallion learns the game plan and gains confidence, no longer needing medication.

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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