Use of Pharmacologically Induced Ejaculation to Obtain Semen from a Stallion with a Fractured Radius
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’ EQUINE Use of pharmacologically induced ejaculation to obtain semen from a stallion with a fractured radius Regina M. Oristaglio Turner, VMD; Sue M. McDonnell, PhD; Jan F. Hawkins, DVM α 1-3 α-Adrenergic agents can successfully induce ditional -adrenergic stimulation. A collection ex copula ejaculation in stallions with injuries device consisting of an embroidery hoop (15 mm that would preclude normal sexual arousal, in diameter) and attached plastic baga was posi- mounting, or thrusting. tioned over the stallion’s prepuce and held in place Ÿ Genetic material from valuable stallions with with a girth strap fashioned out of elastic bandage life-threatening or debilitating injuries can be wrap.b Six minutes later, 900 mg of clomipramine preserved by freezing semen obtained by (2.2 mg/kg of body weight) was administered IV pharmacologically induced ejaculation. through a previously placed indwelling jugular cath- eter. Penile erection was detected 7 minutes after 13-year-old Quarter Horse stallion was admit- administration of the clomipramine. Penile erection A ted for surgical repair of a spiral fracture of the and masturbation were noticed intermittently, ac- radius. The fracture was repaired, using internal companied by dripping of presperm fluids, but the fixation, and recovery from anesthesia was uncom- stallion did not ejaculate. Fifty-five minutes after plicated. Two days after repair of the fracture, the clomipramine administration, 200 mg of xylazine stallion had signs of abdominal pain. Palpation per (0.5 mg/kg) was administered IV through the jug- rectum revealed a cecal impaction. The impaction ular catheter. Approximately 2 minutes after xyla- was corrected surgically, and recovery from anes- zine administration, the horse ejaculated semen in thesia again was uncomplicated. After surgical cor- a series of 6 ejaculatory jets. After clomipramine rection of the cecal impaction, the stallion had in- treatment, the horse was quietly alert to barn activ- termittent pyrexia and was gradually becoming ity. Within 30 seconds of xylazine administration, increasingly lame on the fractured limb. Eleven the horse reached a plane of light sedation, but re- days after internal fixation of the radius, radiogra- mained standing. phy revealed disruption of the fracture repair. Be- While ejaculation was being induced, prepa- cause of failure of the fixation, euthanasia was rec- rations were made for immediate evaluation, proc- ommended. The owners inquired about the possi- essing, and freezing of the semen. Within 5 minutes of collection, the ejaculate was evaluated, using bility of semen collection and freezing prior to 4 euthanasia of the horse. guidelines established by Kenney et al. Although Because of the horse’s fracture, it was unlikely the sperm concentration and total number of sper- that semen could be collected by standard tech- matozoa in the ejaculate would have been adequate niques that involved pelvic thrusting while standing to allow immediate addition of extender and to at- or mounted. Pharmacologically induced ejaculation tempt freezing, poor motility rendered the ejaculate with the stallion standing quietly in a stall was rec- unsuitable for freezing. Morphologic assessment of ommended. If semen could be obtained without the sperm was not performed in light of the poor undue stress to the stallion, and if results of a se- motility (Table 1). men freezing test were satisfactory, the owners were . willing to prolong the life of the stallion for 24 to Table I-Results of evaluation of semen samples obtained 48 hours to allow for collection and freezing of ad- from a 13-year-old Quarter Horse stallion with a spiral frac- ditional ejaculates. The testes were palpated prior ture of the radius to collection and were found to be soft. Source of sample It was decided to initially administer clomipra- Pharmacologically* Epididymal… mine hydrochloride in an attempt to induce ejac- Variable induced ejaculate aspiration/flush 1 Volume (ml) 4 < 0.5 ulation with minimal sedative effects. If ejaculation 6 6 was not induced within the first hour, xylazine hy- Sperm concentration (per ml) 1,188 x 10 1,100 x 10 Total No. of sperm (x109) 4.75 ND drochloride would be administered to provide ad- Total motile sperm (%) <5 <5 Progressively motile sperm (%) 0 1 From the Sections of Reproduction (Turner, McDonnell) and *Collected after administration of clomipramine hydrochloride and xylazine Large Animal Surgery (Hawkins), School of Veterinary Medicine, hydrochloride. …Collected after stallion was euthanized. New Bolton Center, University of Pennsylvania, 382 W Street ND = not determined. Rd, Kennett Square, PA 19348-1692. 1906 Clinical Report JAVMA, Vol 206, No. 12, June 15, 1995 The stallion was euthanatized, using an over- and freezing of epididymal sperm have not been c dose of barbiturate. Within 10 minutes of eutha- performed successfully in clinical situations. nasia, the testes were removed. The epididymides The ejaculatory reflex currently is understood to were separated from the testicular parenchyma and be primarily an α-adrenergically mediated event.12 were minced. Spermatozoa were aspirated and a -Adrenergic agents such as imipramine and clo- flushed from the tail of the epididymides and eval- mipramine are used widely in human beings as anti- uated for motility. Although motility of the epidid- depressants and are known to influence erection ymal sperm was slightly better than that of the and ejaculation.13-15 Disturbances of or facilitation ejaculated sperm, it was still inadequate for freezing of sexual response, including orgasm and ejacula- (Table 1). Longevity of motility was extremely poor, tion, are potential effects of treatment with these with none of the sperm having progressive motility compounds.l6 In addition to their α-adrenergic ef- after 3 minutes in a skim milk/glucose extender at fects, these tricyclic compounds have several effects ambient room temperature (approx 22 C). in the CNS involving norepinephrine, dopamine, Although pharmacologically induced ejacula- and serotonin systems, each of which plays a role tion has been attempted in clinically normal horses, in male sexual arousal, erection, and ejaculation.17 as well as horses with ejaculatory dysfunction and α-Adrenergic agents have been used to induce 3,5 aorto-iliac thrombosis, it has not been reported ejaculation in stallions. In horses, imipramine in- in a clinical situation involving a horse with a de- duces penile erection and masturbation, and in- bilitating musculoskeletal injury. In experiments creases ejaculation during masturbation5 This tech- that used pony stallions, a combination of imipra- nique does not require a mare for sexual stimulus, mine and xylazine induced ejaculation without prior nor does it require any physical activity on the part 1 sexual stimulation in 10 of 24 (42%) trials. In the of the stallion. The only prerequisite is that the stal- disabled stallion reported here, ejaculation was lion stand quietly during the procedure.3,5 Xylazine smoothly and efficiently induced, and an ejaculate is an a -adrenergic agonist used routinely in veter- representative of the stored epididymal sperm was inary medicine as a sedative and analgesic for dogs, obtained. The ejaculate had a sufficient concentra- cats, and horses.18 It has been reported anecdotally tion of sperm, such that it could have been im- that an ancillary effect of xylazine use in stallions mediately extended and frozen. is ejaculation within a few minutes of IV injection. Many owners of stallions with disabling con- These horses ejaculate without developing penile ditions desire an evaluation of a stallion’s potential erection and without masturbating. fertility so that informed decisions can be made on Imipramine1 and xylazine1,3 have been evalu- the cost effectiveness of veterinary care. In addition, ated in experiments that were conducted on clini- owners of valuable stallions with life-threatening cally normal stallions for the specific purpose of de- disabilities often inquire as to the possibility of pre- veloping protocols for pharmacologically induced serving a stallion’s genetic qualities through the use ejaculation. Despite research, the ideal protocol for of semen freezing prior to further deterioration of pharmacologic induction of ejaculation in debili- the horse’s condition. Physical disabilities may pre- tated stallions has not been established. In the clude the use of standard semen collection tech- horse described here, we attempted to tailor the niques. In some of these cases, semen collection protocol to the stallion’s unstable musculoskeletal that uses an artificial vagina or manual stimulation condition. In our experience, doses of imipramine can be attempted with the stallion standing on the or clomipramine that induce ejaculation result in ground, thus eliminating the need for the stallion minimal musculoskeletal instability and little seda- to mount a mare or dummy.6,7 However, because tion compared with doses of xylazine that induce the horse must become sexually aroused and thrust ejaculation. Therefore, we proceeded initially with vigorously, use of these techniques still are limited clomipramine treatment. Although penile erection by the physical condition of the stallion and, in and masturbation were observed, the stallion had most cases, the need for immediate availability of a not ejaculated by 55 minutes after clomipramine mare.6 Furthermore, some stallions require a period administration. In healthy pony stallions that did not