Libido, Erection, and Ejaculatory Dysfunction in Stallions handler education and relatively sim- terone and boost libido. The greatest ABSTRACT Continuous access to mares and ple and inexpensive management improvement in libido with testos- skillful handling are generally the best ap- changes (see Management Conditions terone treatment typically occurs af- proaches to dealing with inadequate libido to Maximize Libido in Breeding Stal- ter 4 to 7 days of treatment. Although in stallions. Although the problem can oc- lions). Housing that provides ample it is often tempting to increase cur in experienced stallions, it is more continuous exposure to mares and re- the dose of testosterone, there is common in slow-starting novices. Erection duced contact with other stallions concern about possible adverse side dysfunction primarily occurs subsequent to traumatic injury of the penis, such as naturally drives stallion endocrinology effects on pituitary gonadal function. kick injuries or semen-collection acci- and behavior in a positive direction.* Personnel must be taught that hor- dents. Ejaculation dysfunction can result Patient, quiet handling in the breed- mone treatment that increases sexual from neurologic and musculoskeletal or ing situation will almost always be behavior is likely to simultaneously ejaculatory apparatus problems. more effective than any other ap- increase aggressive behavior. If the proach. I recommend as little restraint aggression is not anticipated and as safely possible under the particular carefully directed or abided, mare or University of Pennsylvania conditions, as much positive rein- handler interaction with the stallion Sue M. McDonnell, PhD forcement as possible, and avoidance can be counterproductive. Hormone of punishment and negative experi- treatments usually can and should ences. Continuous free-pasture access be withdrawn after a slow-starting exual behavior dysfunction in to mares for several breeding stallions primarily in- days or weeks often al- H Inadequate libido can usually be effectively S cludes libido or ejaculation prob- lows the stallion to gain managed with handler educauon and simple, lems. Libido-independent erection experience and confi- nomic management changes. dysfunction is relatively rare in stal- dence “naturally.” This Limiting mounting attempts, employing pharma- lions and mostly limited to penile almost always enables cologic aids, and other management changes can trauma complications. This column an easy transition to in- reduce the work of a stallion with neurologic- or discusses stallion sexual behavior dys- hand breeding. musculoskeletal-related ejaculation dysfunction. function with a focus on recently de- If results must be Ejaculatory apparatus problems include appar- veloped therapeutic approaches. produced. quickly, ex- ent dysfunction of the neural ejaculatory appa- ogenous hormones to ratus, pain associated with ejaculation, and geni- Inadequate Libido increase circulating tal. tract pathology that may physically impair or The most common type of inade- steroids can sometimes cause pain during ejaculation. quate libido involves slow-starting speed nrogress.2 Short- novice stallions. In most cases, the term treatment with gonadotropin- novice stallion has had a few success- primary cause is simply inexperience releasing hormone (50 ug subcuta- ful breedings. with domestic breeding conditions neously 2 hours and 1 hour before Experienced stallions can also de- rather than physiologic immaturity breeding) or aqueous testosterone velop inadequate sexual arousal; this or an endocrine abnormality. (50 to 80 mg subcutaneously every is often variable rather than consis- The keys to efficient turnaround other day for at least 1 week) can ef- tent. Primary causes for variable or for these stallions primarily involve fectively increase circulating testos- consistent low libido in experienced SERIES EDITOR nis folding back within the prepuce Management Conditions to Maximize Libido as tumescence commences. Typical- in Breeding Stallions ly, the stallion appears aroused and ready to mount despite no visible General Housing and Care n Provide as much contact (direct, fence line, or in neighboring stall) with erection. The stallion may also ap- mares as possible and as little contact as possible with other stallions. pear uncomfortable or intermittently n Provide ample outdoor exercise and good ventilation when indoors. distracted, pinning the ears, kicking n Keep stallion fit and lean. toward the abdomen, or stepping awkwardly on the hind legs. Close vi- Breeding-Shed Experience sualization reveals a rounded, full- n Provide ongoing in-hand exposure to mares in a breeding situation (I appearing prepuce with the skin recommend one or two 30-minute sessions daily or every other day). stretched taut as the penis doubles q Provide exposure to a variety of stimulus mares in natural estrus, including both quiet and more active mares. Allow interaction with the back on itself within the prepuce. mare’s head, body, and tail; movement of the mare, particularly slow Resolution usually requires removing walking and stopping, is typically more stimulating to a stallion than the stallion from the sexual situation is a fully restrained mare. until the penis detumesces. After the n Provide patient, creative, and skilled handlers who can confidently penis is fully withdrawn, applying a and quietly control a stallion that is showing normal vigorous sexual lubricating ointment to the prepuce behavior. is usually adequate to facilitatesubse- n Allow mounting without an erection; this is a normal behavior of quent normal protrusion. stallions that can be eliminated once the stallion is breeding normally. This situation tends to repeat occa- n Expect an irregular rate of improvement. sionally over time with particular stal- lions. I have noted this condition to re- breeding stallions include handling Erection Dysfunction peat in stallions that accumulate large changes, negative experience associ- Penile erection in a sexual context amounts of smegma as well as in stal- ated with breeding, a heavy breeding depends on adequate sexual arousal lions in which the penis and sheath are schedule, suboptimal stimulus mares, and a functional pelvic and penile fully cleansed one or more times daily testicular degeneration, musculo- neurovascular apparatus.’ Libido-inde- for breeding. One might speculate that skeletal discomfort, or other. pain or pendent erection dysfunction is rare in this tendency may be related to too illness. It is usually difficult to deter- breeding stallions. The majority of much accumulated “sticky” smegma or mine the causal factors. However, I cases that do occur are subsequent to too little normal smegma lubrication. I recommend treating any suspected traumatic injury of the penis, includ- have seen one stallion appear to suffer discomfort and then proceeding as ing stallion-ring injuries, paralyzed pe- secondary psychologic libido dysfunc- described for a slow novice, review- nis and paraphimosis, kick injuries, tion associated with a relatively fre- ing all possible contributing factors and other ‘breeding or semen-collec- quent occurrence of this event. with the goal of optimizing all as- tion accidents. Artificial-vagina inser- Erection is not requisite for semen pects of the breeding and manage- tion problems are relatively common, collection in stallions with an active ment environment. particularly with “self-serve” dummy libido. Vigorous manual and thermal mounts. Another common semen-col- stimulation of the base of the penis Rowdy Breeding-Shed Behavior lection accident involves penile lacera- typically elicits pelvic thrusting ade- Stallions are by nature quite variable tion associated with the failure to re- quate to achieve ejaculation, either in their level of sexual arousal. High li- move a thermometer from the lumen with the horse mounted or standing 9 bido can be problematic for some of the artificial vagina. on the ground. Pharmacologic aids breeding operations. The handling Although rare, aortoiliac thrombo- to enhance erection or enhance or in- challenge is to safely direct and accom- sis that impairs pelvic circulation can duce ejaculation without erection can modate energetic stallions without dis- result in inadequate tumescence, par- also be useful in prolonging the couraging normal sexual behavior (see ticularly on exertion during mounting breeding life of stallions with inade- Management and Pharmacologic Aids and thrusting. Neurologic disease can quate erection. to Facilitate, Ejaculation). Case reports also be manifest in erection dysfunc- detailing the implementation of these tion (e.g., premature and exaggerated Ejaculation Dysfunction handling recommendations have been tumescence of the glans penis).8 Neurologic and Musculoskeletal published and can be useful reading A potentially confusing type of Problems for most stallion managers.” erection dysfunction involves the pe- Most cases of ejaculatory dysfunc- ment, or using chilled or frozen se- Management and Pharmacologic Aids men can also reduce the work of a to Facilitate Ejaculation stallion (see Management and Phar- macologic Aids to Facilitate Ejacula- To enhance sexual arousal tion). My general approach is to con- n Excellent stallion handling sider and simultaneously implement W Prolonged teasing ,under conditions that yield the highest safe level of as many appropriate aids as possible. arousal m Breeding schedule for maximum arousal m Natural estrus stimulus and mount mares Ejaculatory