How We Select, Prepare, and Maintain a Stimulus/Mount Mare. 59Th

AMBULATORY PRACTICE How We Select, Prepare, and Maintain a Stimulus/Mount Mare Kristina Janson Whitesell, DVM*; and Sue M. McDonnell, MS, PhD, CAAB A stimulus/mount mare that is an easy keeper, sound, and reliably attractive and receptive to most stallions, as well as comfortable with her work and easy to handle, is invaluable to a breeding facility. Organized and systematic behavior evaluation specific to your clinic’s protocols before selection will reveal undesirable behaviors that may prove unsafe in the semen collection environment or may complicate or prevent successful semen collection. In the case of intact mares, bilateral ovariectomy performed through colpotomy or a hand-assisted laparoscopic approach with colpotomy allows for a short convalescent period compared with other approaches. Additionally, flank sensitivity can be avoided by colpotomy. In the absence of functional ovaries, frequent, low-dose estrogen supplementation can usually maintain estrus adequate for a stimulus/mount mare. Authors’ ad- dress: School of Veterinary Medicine, University of Pennsylvania, New Bolton Center, 382 West Street Road, Kennett Square, PA 19348; e-mail: [email protected]. *Corresponding and pre- senting author. © 2013 AAEP. 1. Introduction ural cover. Accordingly, a commonly used alterna- Although some stallions, initially or after training, tive to a cycling mare in estrus is a mare without respond adequately for semen collection in the ab- functional ovaries that is administered exogenous sence of a live mare, most semen collection facilities estrogen as needed to maintain estrus at a level do require a live mare to accommodate stallions that sufficient for the needs of the facility. do not respond. A cycling mare in natural estrus In a quantitative study of the behavior of 10 ovari- close to ovulation is typically the most stimulating to ectomized and 10 seasonally anestrus mares, Asa et 1 stallions. However, to ensure availability of a suit- al reported that 17 of the 20 mares showed some able mare in estrus on any given day throughout the degree of receptivity (tolerance of the stallion’s ap- year, a fairly substantial herd of monitored/cycle proach, teasing, mounting, insertion) on most test manipulated mares from which to choose is typically days. The probability of any particular mare exhib- required. It has long been known that in the ab- iting estrus on any test day in their study was re- sence of ovarian steroid hormones, whether during ported to be 50%. The intensity of estrus observed anestrus, in certain karyotipic abnormal states was comparable to that of mares transitioning be- (XO), in senescence, or after ovariectomy, mares can tween estrus and diestrus phases, which is less in- show estrus sufficient to stimulate response of most tense than is typical of the day before and the day stallions for semen collection as well as tolerate of ovulation. This study also quantitatively con- mounting for semen collection or schooling for nat- firmed the long-time anecdotal observations of wide NOTES AAEP PROCEEDINGS ր Vol. 59 ր 2013 23 AMBULATORY PRACTICE variation in the degree of proceptivity (solicitous- Systematic Behavior Evaluation ness), receptivity (tolerance of mounting), and at- If a mare meets those initial behavior and sound- tractivity (stallion sexual response) of mares ness selection criteria, we then systematically eval- without ovarian steroid influence, both among uate her behavioral comfort and compliance with a mares and from day to day within-mare. Only one battery of anticipated breeding shed protocols for of the 20 mares was observed to exhibit estrus on all semen collection, breeding, and schooling of stallions 15 observation days of the study. In a follow-up specific to the environment in which she will be study of steroid hormone treatment of ovariecto- used. Winter anestrus presents an ideal opportu- mized mares, it was demonstrated that estrogen nity for this evaluation because it most closely treatment increased the intensity and decreased approximates the ovariectomized condition. How- variation in estrus as well as correspondingly in- ever, for mares that are not anestrus, we of course creased the intensity and decreased the variation in evaluate the specific breeding shed tasks when she stallion response.2 Estrogen-treated mares showed is in estrus. strong estrus for 80% of the tests and weak estrus Comfort and compliance with tasks specific to the for an additional 3%. Untreated mares showed stimulus/mount mare occupation in our teaching strong estrus in only 23% of tests and weak estrus and clinical environment include tolerance and for an additional 33%. comfort with application of a twitch, breeding cape, This report presents our experience with selection hobbles, breeding boots, and tail wrap; expression of of candidates for stimulus/mount mares as well as proceptive and receptive responses as well as attrac- preparation and estrogen treatment of ovariecto- tivity to stallions both with and without a twitch; mized mares for comfortable, effective, and safe use easy “steerability” with and without a twitch; ease in an equine reproduction and behavior teaching and comfort with loading, standing for long periods, clinical and research facility with a variety of and unloading in stocks or adjacent the dummy unknown and known stallions of various breeds. mount; absence of tendency for non-receptive or dis- These circumstances necessitate year-round avail- comfort responses (striking, squealing, biting, kick- ability of reliable stimulus mares that are also com- ing, striking, “bunny hopping,” rearing, slapping or pliant with mounting for semen collection, novice swishing tail, moving away, pinning ears, tensing stallion schooling, and a variety of other reproduc- up, cowering) even with prolonged teasing; tolerance tion teaching exercises involving rotating staff and of mounting by a test stallion wearing an “apron” students of various levels of handling ability and (for teaching purposes). We aim to evaluate the stallion and mare response with stallions of various horse breeding experience. ages, experience, breeds, and breeding tempera- ments. Because we are a teaching facility with 2. Candidate Selection day-to-day variation in the handling team, we also try to assess the candidate’s cooperation and comfort Initial Considerations with handlers of various skill levels and handling When considering particular mares as candidates styles. A particular concern is to identify behavior for preparation to be a stimulus/mount mare, we that would pose safety threats for less experienced first try to identify candidates with (1) a behavioral student handlers in a teaching environment. Fig. 1 history of excellent temperament and interaction illustrates an example check sheet that we use to with humans and other horses, both for general record test session findings. Fig. 2 includes a series ground handling as well as when interacting with a of images from a candidate evaluation session. stallion for estrus detection or breeding, and (2) generally good health, soundness, and ease of main- 3. Preparation taining good body and particularly foot condition. The goal of a dedicated stimulus mare is to remove We also consider the age of the mare because there the limitations of cyclicity and seasonality encoun- is considerable effort and expense to preparation, tered when selecting mares to aid in semen collec- and we prefer to expect as many years of service as tion. This can be achieved through ovariectomy possible. Although there are no data to confirm the and subsequent estrogen replacement or estrogen concepts, we consider the tendency for (1) demon- replacement alone for mares with non-functional strative estrus for several days each cycle and (2) ovaries. less frequent and demonstrative aggressive responses to stallions during diestrus to be predictive Ovariectomy of better performance and comfort as a stimulus/ Various approaches for ovariectomy in the mare mount mare. If this history is known, we certainly include colpotomy, flank laparotomy, paramedian take it into consideration. Also, because of our ex- celiotomy (oblique or caudal), ventral midline celiot- perience with apparent color, breed, and size pref- omy, and various laparoscopic techniques, either erences and aversions among stallions, we aim to conventional or hand-assisted as summarized by maintain a variety of these characteristics among Loesch and Rodgerson.3 A complete discussion of our available stimulus/mount mares. surgical technique is beyond the scope of this report; 24 2013 ր Vol. 59 ր AAEP PROCEEDINGS AMBULATORY PRACTICE Fig. 1. Example check sheet for systematic behavior evaluation of stimulus/mount mare candidates. however, consideration of the implications of the scopic approach carries the advantage of improved various approaches for intended use as a stimulus/ visualization of the ovary and mesovarium over mount mare is warranted. Flank incisions not only the flank approach, extension of portal incisions to require an extended convalescent period (4 to 6 facilitate extraction of the ovary is still necessary. weeks), but, in our experience, flank incisions often Therefore, postoperative healing time, incisional result in an aversion to flank contact that not only complications, and persistent flank sensitivity are complicates mounting by a stallion for semen collec- concerns for a stimulus/mount mare. Recently, tion through the use of the artificial vagina or as an hand-assisted techniques have been developed to intermediate

Load more