b'YOUR GUIDE TO THE 2017 AAEP CONVENTIONultrasound is a critical tool in determin-ing a mares hormonal state.Going back to the initial list of per-in the survey, its evident that it includes Mares and Theirformance-affecting behaviors vets noted behaviors associated with both estrogen Vanderwall, some problematic behaviors that get blamed on estrus are, in fact, Hormones and progesterone. Furthermore, said signs of submissive behavior, urogenital discomfort, or stallionlike behavior.So, when evaluating a complaint of an estrous-cycle-related behavior or perfor-mance problem, the veterinarian should first determine whether the problematic behavior is or is not related to the repro-ductive status of the mare, he said.This includes a complete physical exam to rule out other medical conditions and gathering a history to determine if the behavior correlates with reproductive events. Then the vet can perform tran-ISTOCK.COM srectal palpation and ultrasound exam to evaluate the reproductive tract.MICHELLE ANDERSON; If the mare is cycling, Vanderwall behavior is estrogen, he said. Progester-ALEXANDRA BECKSTETT one is key to blocking estrous behavior. recommends tracking her reproduc-When a mare is in heat, her estrogentive status over one or more cycles. This Mare-ish: Are the Ovaries to Blame? levels are high and her progesterone low.involves performing transrectal palpation eproductive behavior in maresPost-ovulation, progesterone levels rise. and ultrasound twice a week for three to can range from annoying toLike many mammals, horses arefour weeks. The vet might identify signs performance-limiting. For thisseasonal breeders. In winter, maresof pain during manual evaluation of thereason, many mare owners and their vet- hypothalamic-anterior pituitary-ovarianovary, back sensitivity, or coliclike pain. In erinarians try to control or eliminate it.axis (which regulates reproductive pro- the latter two scenarios, the mare might However, how do you really know if hercesses) is inactive, while in summer its atbenefit from an ovulatory agent to reduce reproductive system is to blame? its peak. During the spring and fall its ac- the time the follicles present on the ovary, Dirk Vanderwall, DVM , PhD, Dipl.tivity increases and decreases, respective- or administration of hormones to sup-ACT, a professor of horse reproduc- ly, with transitional times of prolonged orpress ovarian follicular activity, he said.tion at Utah State Universitys School ofirregular estrous activity. If these serial exams confirm the mares Veterinary Medicine, in Logan, addressedIn addition to their effects on marehormonal status correlates with her prob-this concern and offered ways to managebehavior, estrogen and progesteronelematic behavior, Vanderwall said the vet undesirable behavior. profoundly affect the physical andmight prescribe hormone therapy (e.g., He first cited a survey of more than 750ultrasonographic characteristics of thealtrenogest) to mimic diestrus (the period vets in which 90% believed the estroustubular genitalia, said Vanderwall. Thus,between estrous cycles), prolong diestrus cycle affects mares performance. Based(e.g., oxytocin), mimic/induce the winter on that survey, the most frequently report- anovulatory state (e.g, via ovariectomy, or ed performance-inhibiting clinical signovary removal), or mimic/induce estrus associated with cycle was attitude change.(e.g., the prostaglandin PGF2).Others included tail-swishing, difficultySumming up, Vanderwall said vets training, squealing, excess urination, kick- should perform a careful assessment of a ing, and diminished performance.Alexandra Beckstett mares hormonal status/reproductive state But before getting into the possible@TH_ABeckstettto see if theres a definitive, repeatable causes, Vanderwall reviewed mare repro- Dr. McDonnell: ~2/3 ofrelationship between it and her behav-ductive physiology and seasonality.cases referred to theirior. If so, it behooves them to use an The key ovarian hormones regulatingclinic for ovariectomiesevidence-based approach when attempt-reproductive behavior are estrogen andwould not have responded.ing to regulate reproductive behavior and progesterone. The primary hormonalThe root cause was notto choose the most appropriate treatment product driving the display of estrousestrus-related.to eliminate the underlying causes.A28 TheHorse.com/AAEP2017 AAEP Wrap-Up THE HORSEMarch 2018'