Fertility in horses encompasses the physiological processes and factors influencing reproductive success in equine species. It involves the study of reproductive anatomy, endocrinology, and behavior, as well as the management practices that affect breeding outcomes. Key aspects include the estrous cycle, conception rates, and factors impacting stallion and mare fertility. Reproductive technologies such as artificial insemination, embryo transfer, and hormonal therapies are also explored to enhance breeding efficiency. This page compiles peer-reviewed research studies and scholarly articles that examine the biological mechanisms, management strategies, and technological advancements related to equine fertility.
Hurtgen JP, Johnson LA.During a 2-year period, 7 stallions were identified as having ejaculated spermatozoa characterized by a high incidence (27-74%) of acrosomal abnormalities. The most frequent abnormality of the acrosome was the 'knobbed sperm' defect which was observed in nigrosin--eosin, Giemsa, and haematoxylin and eosin stained semen smears under light microscopy, in buffered formal--saline and in glutaraldehyde-fixed wet mounts under phase contrast and differential interference microscopy, and in glutaraldehyde-fixed spermatozoa with electron microscopy and scanning electron microscopy. The defect was visib...
Mitchell G, Liu IK, Perryman LE, Stabenfeldt GH, Hughes JP.Immunoglobulin concentrations were compared in serum and in saline uterine washings from 10 normal mares and 7 subfertile mares with chronic endometrial pathology. Samples were collected in dioestrus and in oestrus. For each immunoglobulin class (IgA, IgG, IgG(T), IgM) the results were expressed as a percentage of total immunoglobulin present in uterine washings or serum. Comparison was also made between changes in immunoglobulin concentrations between dioestrous and oestrous uterine samples, and uterine immunoglobulin concentrations between groups of mares. There was significantly more IgA in...
Klug E, Deegen E, Lazarz B, Rojem I, Merkt M.Successful empirical treatment of 17 out of 24 stallions, which had failed to ejaculate after normal penile erection, intromission and friction, by chemical blockage of beta-receptors and additional stimulation of alpha-receptors led us to investigate stallions with normal ejaculatory patterns. In an initial experiment one adult half-bred stallion was injected with 4.88 mg noradrenaline hydrochloride (treatment A), 10 mg bunitrolol (treatment B = beta-receptor blockage) and a combination of treatment A and B. Investigations of the same stallion on dated occasions without treatment served as co...
Webel SK, Squires EL.The clinical effectiveness of the synthetic progestagen, altrenogest, was evaluated in field trials with 449 mares during the 1980 breeding season. An oral dose of 27 mg altrenogest was administered daily for 15 days. In the first trial treated mares were compared with controls, and in the second trial the effectiveness of treatment for prolonged or erratic spring oestrus was evaluated. Oestrus was suppressed in 94% of the treated mares in the first trial. The post-treatment response was related to the stage during the transition from winter anoestrus to the spring breeding season and degree o...
Rideout MI, Burns SJ, Simpson RB.Sterile filtrates were prepared from equine isolates of Klebsiella pneumoniae (genitalium), Proteus mirabilis, Pseudomonas aeruginosa, Escherichia coli, Streptococcus zooepidemicus, Streptococcus equisimilis, Actinobacillus equuli, and Corynebacterium equi and mixed individually with extended stallion semen. When diluted in the extended semen the filtrates represented bacterial populations of 0.5 x 10(6), 1 x 10(6), 2 x 10(6) and 4 x 10(6) cells/ml. pH values were recorded for each filtrate. Specimens were monitored for percentage motile spermatozoa at 30-min intervals until they reached 10% o...
Woods GL, Ginther OJ.The ability of a pituitary extract to induce ovulation and the effect of multiple ovulations on pregnancy rate and incidence of multiple fetuses were studied in seasonally anovulatory mares. The extract induced ovulation in 95% of mares having a greater than or equal to 25 mm follicle at the onset of treatment and in 64% the ovulations were multiple. The extract was less effective when the largest initial follicle was less than 25 mm. Approximately 50% of the treated mares that ovulated did not become pregnant or enter prolonged dioestrus before returning to an anovulatory condition. In treate...
Taylor TB, Pemstein R, Loy RG.Two trials were conducted to (1) determine the degree of control of ovulation achieved by treating mares in late winter with progesterone and oestradiol-17 beta combined after prior exposure to an artificially increased photoperiod, and (2) to examine the effectiveness of such a procedure incorporated into equine breeding farm management systems. Following a 15-day treatment of 150 mg progesterone and 10 mg oestradiol-17 beta daily with 10 mg PGF-2 alpha on the last day of steroid treatment, 27 of 31 mares ovulated on Days 8-14 after the last injection in one trial. Conception rate for mares m...
Shivers CA, Liu IK.Sera and follicular fluid from mares previously determined as having antibodies to the zona pellucida were exposed to porcine ovarian oocytes before insemination with boar spermatozoa in vitro. There was a dramatic decline in the number of spermatozoa bound to zonae compared to treatments with sera and follicular fluid from mares negative for zona antibodies. These data suggest that antibodies reactive with the zona pellucida may be responsible for reduced or even complete infertility in some mares. In a group of 50 randomly selected mares tested for antizona antibodies, 2 pregnant mares were ...
Kreider JL, Ogg WL, Turner JW.Six mature stallions were used to test the effect of prostaglandin F2 alpha (PGF2 alpha ) on sperm production and seminal characteristics. Semen was collected from each stallion twice weekly 1 hr following a 10 mg intramuscular injection of PGF2 alpha or a sham injection. A switchback design was used so that three stallions received PGF2 alpha and three served as controls during the first 9 weeks (period 1). Treatment regimens were reversed during the second 9 weeks (period 2). Treatment of stallions with PGF2 alpha resulted in an increase (P less than .05) in gel free seminal volume and a dec...
Imel KJ, Squires EL, Elsden RP, Shideler RK.Embryos were recovered in 39 of 47 attempts (83%) during 1979 and in 75 of 104 attempts (72%) during 1980. The mean diameters of day 8 and 9 blastocysts were 1.00 and 2.13 mm, respectively. The injection of prostaglandin F2 alpha or prostalene on day 8 or 9 after ovulation resulted in a mean interval between embryo recovery attempts of 17.7 +/- 0.3 days. Number of embryos recovered within mares did not vary significantly with repeated attempts. Following surgical transfer, 8 of 15 recipients (53%) were pregnant at 50 days after ovulation, whereas only 4 of 15 recipients (27%) were pregnant at ...
Squires EL, Berndtson WE, Hoyer JH, Pickett BW, Wallach SJ.Twelve stallions that had been given 0, 50 or 200 micrograms testosterone propionate (TP)/kg body weight every other day for 88 days were examined for the effects of androgen withdrawal on spermatozoal production, seminal quality and libido. Although the lower dosage did not affect most of the traits studied, the higher dosage severely reduced scrotal width, spermatozoal production, the number of sperm per ejaculate, the percentage of progressively motile spermatozoa and the percentage of normal spermatozoa. These adverse effects were found to be largely reversible. By 90 days after the cessat...
Vandeplassche GM, Wesson JA, Ginther OJ.Sexual behavior, follicular development and ovulation, and concentrations of circulating gonadotropins during the estrous cycle were studied during the summer in 7 jennies. Mean behavioral estrous length was 6.4 +/- 0.6 days (mean +/- SEM, n=19; 5.6 +/- 0.5 days preovulatory and 0.8 +/- 0.2 days post-ovulatory). Mean diestrous length was 19.3 +/- 0.6 days (n=14). Females in estrus typically showed posturing, mouth clapping, clitoral winking, urinating and tail raising. Mouth clapping began approximately one day sooner and lasted approximately one day longer than winking and tail raising, so th...
Guay P, Rondeau M, Boucher S.The effect of different glycerol concentrations (0 to 5.3 per cent) on motility, viability and aspartate aminotransferase (AST) release of stallion spermatozoa was studied before and after deep-freezing. Addition of glycerol to a TRIS-fructose-egg yolk diluent used to extend stallion semen had no effect on motility and viability of spermatozoa and it did not increase AST release. Inclusion of glycerol in the extender only partially preserved the motility and viability of stallion semen during deep-freezing. A fertility trial revealed that concentrating stallion semen by centrifugation, followe...
Stewart F, Allen WR.The role of equine chorionic gonadotrophin (CG, formerly termed Pregnant Mare serum Gonadotrophin, PMSG) in maintaining equine pregnancy was investigated by examining the effects of this hormone on the maternal ovaries during early gestation and relating these findings to the receptor binding activities of CG in vitro. Measurement of plasma progestagen profiles in mares and donkeys carrying horse, donkey, mule ( female horse X male donkey) and hinny (female donkey X male horse) conceptuses confirmed that CG induced several secondary ovulations and thus maintained maternal progestagen concentra...
Wesson JA, Ginther OJ.Reproductive behavior and gonadotropin concentrations were studied in 14 female ponies during the period from 10 to 21 months of age (February 1978 to January 1979). Nine fillies were born during April of 1977 (spring-born) and five were born during the summer and fall of 1977 (late-born). Three of the spring-born fillies had been ovariectomized (OVX) at 4 months of age. All intact spring-born fillies ovulated during late spring when they were 12–15 months old. Two of five late-born fillies did not ovulate, and there tended to be fewer ovulations and a shorter breeding season in late-born th...
Dixon KE, Kreider JL.Fifty ejaculates, ten from each of 5 mature stallions, were utilized to study the effects of calcium and fatty acids on equine spermatozoa which were isolated in 3% Bovine Serum Albumin (BSA). The ejaculates were evaluated for percent motile spermatozoa, rate of forward movement, debris, primary abnormalities and secondary abnormalities. The isolation procedure consisted of layering 2 ml of diluted semen (100 x 10(6) spermatozoa/ml) over 6 ml of 3% BSA in 13 x 125 mm columns in a water bath (37 degrees C). After 30 min., the top semen layer and upper half of the BSA layer were withdrawn from a...
Rowlands IW.The world-wide foaling rate in the mare is low and in the Hannoverian breed has remained asymptotic at about 50 per cent for over 150 years. In an attempt to discover some of the possible reasons for this low fertility rate, the evolutionary history of the perissodactyls, the odd-toed ungulates, is reviewed here. Of the 156 genera of this order, 152 are in the fossil record; this gives them the highest extermination rate of all the mammal groups. Some of the unusual and unique features of the reproductive physiology of the mare and their possible association with low fertility are considered.
Pascoe RR.The effect on the fertility of mares during two outbreaks of equine coital exanthema have been described. Conception was not prevented, nor was pregnancy terminated in mares showing active lesions of coital exanthema. Normal pregnancy rates occurred in mares served during active infection of the stallions. Origin of the disease was not determined.
Munk Z, Dusek J.The fertility problems were studied in the herd of the English Thoroughbred horse on the Napajedla stud farm. Breeding records for the period from 1880 to 1972 were used as the starting data. The survey comprised 32 stallions. The relationship between fertility and the number of matings was calculated by the chi 2 quantity. The calculated values are highly variable. However, it is generally seen in most of the stallions that the number of matings per heat (i. e. one or several matings) had no significant influence on the pregnancy of mares and on the fertility values of the stallions. A higher...
Doig PA, McKnight JD, Miller RB.The results of a study on endometrial biopsies obtained from 700 infertile mares are reported. Infiltrative endometritis was present in 51% consisting of a combination of an acute and chronic cellular response in 6%, mild chronic infiltrations in 35% and moderate to severe chronic infiltrations in 10%. Demonstrable endometrial fibrosis was found in 88% of the mares with the majority having mild (51%) or moderate (35%) changes. The age of the mares and the average number of years barren gradually increased with the severity of endometrial fibrosis, as did the combined incidence of fetal loss (e...
Papkoff H.The objectives of this paper are to review the chemical and biological properties of equine chorionic gonadotropin (eCG, PMSG) isolated from the serum. Comparisons are made with eCG isolated from endometrial cups, trophoblast cell culture medium, and low titer serum. The results show that eCG can vary, depending on the source, in both chemical and biological (LH and FSH activity) properties.
Bartmann CP, Schiemann V.Diagnostic and operative hysteroscopy have offered an advance in equine fertility diagnostic and equine fertility surgery. A distension of the uterine cavity and an establishment of a continuous intrauterine pressure are basic requirements for complete visualisation of intrauterine structures and safe and efficient surgical procedures. Superelevated pressure and resorption of distension media may result in fatal complications. Intrauterine pressure was monitored in 28 healthy di- or anestrus mares during hysteroscopy via a transcervically inserted catheter. Mares were sedated with xylazine and...
Belz JP, Glatzel PS.Because of the mare's ability to conceive very soon post partum a thoroughly performed control of the puerperal period is of particular importance. Cytological examinations of uterine content and histological examinations of uterine biopsy specimens provide more detailed information than microbiological examinations of uterine swabs. Uterine content and uterus biopsy specimens of 55 mares were examined histologically on days 3, 6 and 9 post partum. We observed a heavy polymorphonuclear reaction of the endometrium following disturbed puerperal processes especially in cases of retained placenta....
Raggio I, Lefebvre RC, Poitras P, Vaillancourt D, Goff AK.Multiple pregnancies are still an important cause of noninfectious abortion, stillbirth, neonatal mortality, and significant delays in reproductive performance in mares. Despite new management techniques, reduction in multiple pregnancies is an ongoing preoccupation and challenge for the equine veterinarian. The aim of the present study was to establish a twin pregnancy experimental model in the mare to study the effectiveness of a transvaginal ultrasound-guided embryonic vesicle injection. Mares in heat were inseminated and then received an embryo at day 7 of the estrous cycle. At days 14 and...
Zhang J, Boyle MS, Smith CA, Moore HD.The acrosome of the stallion spermatozoon was visualized by indirect immunofluorescence with monoclonal antibody (18.6) which recognized an integral acrosomal membrane component. Localization was confirmed by electron microscopy using peroxidase labelled antibody. In fresh semen samples (n = 19), 73.9 +/- 9.1% of the spermatozoa from five fertile stallions displayed a uniform bright fluorescence over their acrosome region. In two semen samples from an infertile stallion only 28% and 35% of spermatozoa showed the same pattern of fluorescence. Spermatozoa from fertile stallions incubated for up ...
Araujo GH, Rocha Filho AN, Lopes EP, Moya CF, Alvarenga MA.The effects of a low dose of equine purified FSH (eFSH) on incidence of multiple ovulations and embryo recovery rate in mares were studied. During the physiological breeding season in Brazil (19 degrees 45'45'S), 14 Mangalarga Marchador donor mares were used in a crossover study and another 25 mares of the same breed, between 3 years and 12 years of age were used as recipients for the embryo transfers. Donors were monitored during two consecutive oestrus cycles, an untreated control cycle followed by a treated cycle, when eFSH was administered. In both cycles, after an embryo collection attemp...
Donato GG, Appino S, Bertero A, Poletto ML, Nebbia P, Robino P, Varello K, Bozzetta E, Vincenti L, Nervo T.Mares' subfertility represents a complex diagnostic and therapeutic challenge and both clinical and subclinical endometritis are considered major causes of impaired fertility. Thanks to its properties, ozone has a big potential as a treatment for equine endometritis. Therefore, the aim of this study is to describe the safety and the effects on endometrium and reproductive parameters of mares of a commercial ozone foam preparation (Riger Spray®). Twenty-four mares were treated during estrus: ozone group with an intrauterine instillation of ozone foam preparation (OG, n=16) and control group wi...
Terblanche HM.Parturition was induced in 6 mares between Day 327 and 346 of pregnancy using oxytocin (Group I) and in 6 mares between Day 315 and 330 of pregnancy with fluprostenol in combination with oxytocin (Group II). A third group of 4 mares which served as controls were allowed to go to full term (322-340 days) and foal down normally. Parturition occurred within 24-102 min (mean = 61,4; SD = 31,6) in 5 of the Group I mares and within 160-185 min (mean = 173; SD = 10,86) in the mares of Group II. Expulsion of the afterbirth took place between 7 and 206 min (mean = 79; SD = 76,38) and between 7 and 73 m...
Scherzer J.Mares can be artificially inseminated with chilled or frozen semen to increase the revenue from their offspring. Embryo transfer can be used to produce more than one foal from a single mare per season. Recent advances in using equine follicle-stimulating hormone to induce superovulation in mares have stimulated research on preserving equine embryos. Equine embryos are usually collected on day 7 or 8 after ovulation, and younger (day 6.5) embryos are typically cryopreserved. Cryopreservation improves the ability of veterinary clinicians to preserve embryos for implantation in recipient mares an...
Pascoe RR, Pascoe DR, Wilson MC.Between 1982 and 1985, 1015 mares were evaluated using the following parameters: age, mare status (maiden, barren, lactating), Caslick index, Caslick operation, ovarian cycle, ovarian and follicular size, treatments (hCG and intrauterine infusions), number of ovulations after mating (184 mares), number of conceptuses present, dimensions of embryonic vesicles, and pregnancy status 45 days after mating. Mares were examined ultrasonographically between Days 12 and 25 to detect the presence of embryonic vesicles and measure the dimensions of each vesicle. The data were analysed by a stepwise logis...
Morrell JM, Johannisson A.The effect on sperm motility and chromatin integrity of adding homologous or heterologous equine seminal plasma (SP) to fresh stallion spermatozoa selected by single layer centrifugation (SLC) was studied. No statistical difference in mean progressive motility was seen after adding SP at time 0 h, although there were differences for individual stallions. The proportion of spermatozoa with high velocity was increased compared to untreated SLC-selected spermatozoa (P < 0.05), with significant differences between individuals (P < 0.01). When the SLC samples were stored for 24 h before a...
Glatzel PS, Belz JP.Because of the mare's ability to conceive very soon post partum a thoroughly performed control of the puerperal period is of particular importance. In addition to cytological and histological examinations of the uterus, rectal palpation and vaginoscopic inspection as well as microbiological examinations of uterine swabs and the evaluation of the mare's hormonal status during the puerperal period provide useful information which can be used either prognostically or to initiate a specific therapy. 55 mares were examined on days 3, 6 and 9 post partum. Rectal palpation, vaginoscopic inspection, m...
Raś A, Rapacz-Leonard A, Raś-Noryńska M, Barański W.Although fetotomy is recommended for all mares when the fetus is dead and difficult to extract, little has been written about fetotomy and heavy draft mares. This lack includes indications for fetotomy in heavy draft mares, differences in treatment and prognosis of heavy mares kept by farmers of low socioeconomic status, and how this procedure affects the mare's further fertility. The literature on mares, in general, also differs on the survival rate of mares that undergo fetotomy, the prevalence of postpartum complications, and further fertility. To answer these questions, we reviewed the me...
Deanesly R.During the 340 day pregnancy of the horse, the germ cells in the fetal ovary showed a meiotic prophase which began in days 60-70 and might be prolonged after day 200. Three or four successive oogonial mitotic proliferations passed into the meiotic prophase but the great majority of the oocytes first involved degenerated, and no appreciable numbers of primordial follicles were left behind. At 150 days of pregnancy and again at 197 days, oocytes in early meiotic stages filled the ovarian cortex. Primordial follicles were present, but rare. As the prophase gradually came to an end, groups of oocy...
Cuervo-Arango J, Aguilar JJ, Vettorazzi ML, Martínez-Boví R.The present study characterizes the relationship between the levels of eCG, ovarian morphology, resumption of cyclicity, and fertility in postaborted embryo transfer recipient mares. A total of 32 pregnant recipient mares carrying a male fetus were aborted at approximately 65 days of gestation by single transcervical administration of cloprostenol. In addition, 25 gestation age-matched mares were used as nonaborted controls. The concentration of progesterone, but not of eCG, differed significantly between controls and aborted mares 48 hours after abortion. Of treated mares, 84.4% (27 of 32) ex...
Pruß D, Yang H, Luo X, Liu D, Hegermann J, Wolkers WF, Sieme H, Oldenhof H.Stallion sperm is typically cryopreserved using low cooling rates and low concentrations of cryoprotective agents (CPAs). The inevitable water-to-ice phase transition during cryopreservation is damaging and can be prevented using vitrification. Vitrification requires high cooling rates and high CPA concentrations. In this study, the feasibility of stallion sperm vitrification was investigated. A dual-syringe pump system was used to mix sperm equilibrated in a solution with a low concentration of CPAs, with a solution containing a high CPA concentration, and to generate droplets of a defined si...
Henderson IS, Brama P, Osborne M, Beltman ME.Deslorelin acetate implants, recently licensed in Ireland and the UK for ovulation induction in mares, have been associated with prolonged interovulatory intervals in USA studies, leading to the practice of removing implants postovulation. Trial data in Australia indicate a less pronounced effect on interovulatory intervals, suggesting possible geographical variation. Objectives of the current study were to assess the effect of deslorelin implants, with and without removal on oestrous cycle length in Irish- and UK-based Thoroughbred broodmares. Data were collected retrospectively from 88 oestr...
Evans MJ, Irvine CH.Deeply acyclic (seasonally anovulatory) mares were treated with GnRH or a GnRH analogue to induce follicular development and ovulation. Courses of GnRH (3--4) were administered at approximately 10-day intervals to reproduce the gonadotrophin surges which precede ovulation in the normal cycle. Exogenous progesterone was administered in an attempt to reproduce the luteal phase pattern. Induced serum FSH concentrations were comparable to those causing follicular development in the normal cycle, but induced LH levels were lower and of shorter duration than those of the periovulatory surge. Three o...
Harrison LA, Squires EL, Nett TM, McKinnon AO.Natural GnRH and its analog have potential for hastening ovulation in mares. A study was conducted to evaluate the efficacy of a GnRH agonist given either as an injectable or s.c. implant for induction of ovulation in mares. Forty-five seasonally anestrous mares (March) were assigned to one of three groups (n = 15/group): 1) untreated controls; 2) i.m. injection of the GnRH agonist buserelin at 12-h intervals (40 micrograms/injection for 28 d or until ovulation) and 3) GnRH agonist administered as a s.c. implant (approximately 100 micrograms/24 h for 28 d). Six mares per group were bled on d 0...
Schröer U, Lange A, Glatzel P, Ludwig H, Borchers K.The aim of the present study was to clarify whether an EHV-1 induced abortion can be prognosticated by an increase of antibody titres, virus shedding and/or viraemia and whether the current abortion diagnostic is suitable. In this context the immune response post immunization and a possible reactivation were of great interest. For this purpose blood samples of 32 mares between the ages of 5-21 years were regularly investigated during a period of two years before and after vaccination and pregnancy. Neutralization tests, indirect immunofluorescence tests as well as PCR and virus isolation were ...
Hyland JH, MacLean AA, Robertson-Smith GR, Jeffcott LB, Stewart GA.The removal of one of twin embryos was attempted by infusion of 24% (w/v) saline into the gestation sac in 2 mares by laparotomy. The treatment was successful in one mare (Case 1) and the untreated embryo remained viable. However, neither foetus survived in the second mare (Case 2). Plasma oestrone sulphate (E1S) concentrations fell immediately after treatment in both mares but recovered to approximately 50% of pretreatment levels in Case 1. In Case 2 plasma E1S concentrations declined steadily and were less than 1 ng/ml within 6 days of treatment. These preliminary results suggest that the me...
Raz T, Green GM, Carley SD, Card CE.Induction of multiple ovulations, or superovulation, may potentially increase the efficiency of equine embryo transfer programs. Our objective was to investigate the effects of equine follicle-stimulating hormone (eFSH) treatment on the success rate of embryo transfer programs in mares. Methods: In the research facility of the University of Saskatchewan, Canada, we studied 12 donor mares and 37 recipient mares during the physiological breeding season. Donor mares were used in two consecutive oestrous cycles: the first served as the control cycle and in the second an eFSH regimen was applied (e...
Weitkamp LR, MacCluer JW, Guttormsen S, McKnight J, Wert N, Witmer J, Boyce P, Egloff J.Reproductive performance of 10 Standardbred stallions was related to the probability that the embryo resulting from a given mating would be heterozygous for transferrin or plasma esterase. Fertility, measured by foaling rate per insemination or by foaling rate per year, showed a highly significant regression on the probability of offspring heterozygosity for transferrin and, to lesser extent, for esterase. Substantial differences between stallions in the slope of the regression line and no deficiency of foals homozygous for either protein suggests that the relationship to fertility is indirect...
Braun J, Schefels W, Stolla R.In 1970 semen from a Haflinger-stallion was frozen by the pellet method. 18 years later semen samples were used to inseminate 4 mares. Inseminations were performed shortly after ovulation with a total number of motile spermatozoa between 150 and 636 x 10(6), the percentage of motile spermatozoa being 20% to 40%. Three mares conceived after a single insemination, one mare got pregnant after 4 inseminations during 3 oestrous periods. Meanwhile, 3 foals were born and one of the mares is still pregnant. The results demonstrate that long-term storage of frozen semen in liquid nitrogen does not impa...
Blue BJ, Pickett BW, Squires EL, McKinnon AO, Nett TM, Amann RP, Shiner KA.Gonadotrophin-releasing hormone (GnRH) was administered subcutaneously to reproductively normal stallions, either in a pulsatile manner (10 micrograms GnRH/2 h; n = 6) or as a continuous infusion (10 micrograms GnRH/2 h; n = 6), and in a pulsatile manner to 9 reproductively abnormal stallions, from February to July, 1988. Hormonal secretion patterns, testicular parameters and semen characteristics were monitored before and during treatment. In general, pulsatile GnRH caused a significant increase (P less than 0.05) in luteinizing hormone (LH) concentrations in the peripheral blood of normal st...
Weber JA, Woods GL, Freeman DA, Vanderwall DK.The objective of this experiment was to contrast the influence of the oviductal and uterine environments on development of Day-2 embryos. Embryos were transferred to oviducts or uteri of synchronous recipient mares, or were incubated in oviductal co-culture, in uterine co-culture or in defined culture medium. Significantly more (P < 0.02) embryos transferred to the oviduct versus the uterus survived until Day 11 after ovulation (5 7 vs 0 7 , respectively). Significantly more (P 0.1) in oviductal co-culture versus uterine co-culture (3 7 vs 6 7 , respectively), or in oviductal co-culture ve...
Cooper MJ.Fluprostenol (ICI 81,008) is a 16-aryloxyprostaglandin, structurally related to PGF2alpha. It is a highly potent luteolytic agent, being effective in thoroughbred mares at a single intramuscular dose of 250 mug and having a wide margin of safety in this species. A total of 941 mares have been treated with fluprostenol in an international trial, for various forms of infertility associated with abnormal persistence of luteal function. These mares were selected for treatment on the basis of clinical examination and 760 (approximately 80 per cent) responded fluprostenol by showing oestrus within s...
Roe H, Macpherson M, Denagamage T, Hopper S, Woodie B, Embertson R.Mare and foal survival are increased with prompt dystocia management. Data regarding mortality outcomes in mares and foals, when mares are recumbent at admission for dystocia resolution, are scarce. Objective: To evaluate recumbency at hospital admission as a risk factor for survival of mares and foals following dystocia management. Subsequent mare fertility was also evaluated. Methods: Retrospective cohort. Methods: Data were obtained from medical records at Rood and Riddle Equine Hospital of mares with dystocia between 1995 and 2018. Mare signalment, ambulation status, survival data and foal...
Squires EL, Garcia RH, Ginther OJ, Voss JL, Seidel GE.Sixty light-horse, nonlactating mares were used to compare the efficacy of equine pituitary extract versus follicle stimulating hormone (FSH-P) for inducing multiple ovulations. On Day 12 of diestrus, mares were assigned to receive 1) no treatment, controls; 2) subcutaneous injections of 750 Fevold rat units of equine pituitary extract once daily; or 3) intramuscular injection of 150 mg of FSH-P twice daily. Ultrasound was used twice daily to visualize follicular changes and ovulation. For mares in Groups 2 and 3, treatment was initiated when two or more follicles > 20 mm were detected, and...
Lowis TC, Hyland JH.The occurrence of fertile oestrus early in the breeding season is of paramount importance to the Thoroughbred industry to facilitate early conception. This paper compares 2 techniques for inducing fertile oestrus in anoestrous mares using either an extended photoperiod alone or together with gonadotrophin-releasing hormone (GnRH) infusions. Eleven mares were placed under conditions of 16 h light and 8 h darkness and 5 of these were implanted with osmotic minipumps delivering approximately 100 ng GnRH/kg/h for 28 days (treated mares). The treated mares ovulated 27.7 days earlier than and concei...
Hinrichs K, Provost PJ, Torello EM.A nonovulating, hormone-treated mare was used successfully as an oocyte recipient. The mare's ovarian activity was suppressed using progesterone and estrogen treatment. This treatment was stopped, then estrogen was administered for 3 d prior to the transfer. An oocyte was recovered from the follicle of a donor mare and was transferred via flank laparotomy into the recipient's oviduct. The recipient mare was inseminated 7 h before transfer. The recipient was treated with intramuscular progesterone from the day after transfer until 47 d after transfer, and then with oral altrenogest until 150 d ...
