Reproduction in horses encompasses the biological processes and mechanisms involved in the breeding and development of equine offspring. This includes the study of reproductive anatomy, physiology, and endocrinology in both mares and stallions. Key areas of interest include the estrous cycle, ovulation, conception, gestation, and parturition. Researchers also examine factors influencing fertility, reproductive technologies such as artificial insemination and embryo transfer, and management practices that impact reproductive success. This page compiles peer-reviewed research studies and scholarly articles that explore the physiological, genetic, and environmental aspects of equine reproduction.
Barber JA, Troedsson MH.A 12-year-old Arabian mare with a history of repeated early embryonic losses gave birth to a mummified fetus. The fetus was not the result of a pregnancy with twins. The mare had been given a progestogen throughout gestation and expelled the mummified fetus at about 325 days of gestation, 2 weeks after progestogen treatment was discontinued. We estimate that the size of the fetus was consistent with a fetal age of 5 months. The mare and mummified fetus illustrated that progestogen administration after 100 days of gestation can promote retention of a nonviable fetus. When the fetoplacental unit...
Turner JW, Liu IK, Kirkpatrick JF.Regulation of local overpopulations of free-roaming feral equids is in demand worldwide for ecological balance and habitat preservation. Contraceptive vaccines have proven effective in feral horses, which breed seasonally, but no data are available for equids such as the burro, which is reproductively active all year round. In the present study, 27 individually identified female feral burros (Equus asinus) roaming free in Virgin Islands National Park (St John, US Virgin Islands; Lesser Antilles) were remotely treated with pig zonae pellucidae (PZP) vaccine. Between January and May, 16 burros w...
Cymbaluk NF, Laarveld B.The effects of dam parity, age at weaning, and preweaning diet were examined in the ontogeny of serum insulin-like growth factor-I (IGF-I) concentrations in foals. Foals born to 13 primiparous and 19 multiparous draft-cross mares were weighed and bled near birth. About one-half of the foals in each group were weaned early (about 13 wk old); the remaining foals were weaned late (about 16 wk of age). Pooled values for serum IGF-I concentrations between birth and 17 wk of age were higher (P < 0.065) for foals born to multiparous (386 ng/ml) than to primiparous mares (237.5 ng/ml). Colts (378 n...
Fitzgerald BP.The purpose of this experiment was to investigate whether N-methyl-D,L-aspartate stimulated gonadotropin secretion in mares and to determine the response in two experimental paradigms where gonadotropin secretion is low or elevated. In Experiment 1, conducted during the breeding season (summer), eight long-term ovariectomized mares were treated daily for 21 d with progesterone plus estradiol (n = 4) or oil vehicle. Beginning on Day 14, each mare received, in a randomized design on alternate days, an intravenous injection of either 0, 0.5, 1.0, or 5.0 mg/kg NMA. Treatment with NMA was not accom...
Bracher V, Mathias S, Allen WR.Placentation between 80 and 220 days of gestation was studied by measurement of fetal dimensions and gross, light and transmission and scanning electron microscopic examinations of the allantochorion and endometrium from 4 fertile mares with no, or very mild, endometrial histopathology and 6 subfertile Thoroughbred mares suffering varying degrees of age-related chronic degenerative endometritis (endometrosis). Spontaneously occurring twin gestation was observed in 3 animals. Several of the subfertile mares had endometrial cysts which showed 2 distinct features during pregnancy: those located n...
Christensen P, Whitfield CH, Parkinson TJ.The ability of the glycosaminoglycan, heparin, and the calcium ionophore, A23187, to induce acrosome reaction in equine spermatozoa was assessed using semen from 3 warmblood stallions of known high fertility. After collection of semen, the spermatozoa were washed and incubated in vitro with heparin or A23187. Incubation periods were 0, 4, 6 or 8 h with 0, 1, 10 or 100 microg/ml heparin or 0, 10, 30 or 60 min with 0, 0.01, 0.1, 1 or 10 microM A23187, respectively. Acrosome reactions were determined by staining the spermatozoa with naphthol yellow S plus erythrosin B, and sperm viability was ass...
Daels PF, Chang GC, Hansen B, Mohammed HO.We have characterized the testosterone secretion pattern during the first 80 d of pregnancy in mares and determined the sources that contribute to circulating testosterone levels during this period. Ten untreated, pregnant mares (Group 1), 10 altrenogest-treated, pregnant mares (Group 2), and 10 altrenogest-treated, pregnant mares in which the CL was eliminated by administration of PGF-2alpha on Day 16 (Group 3) were used in this study. Complete luteolysis occurred following PGF-2alpha administration in all mares in Group 3. Six of the 10 mares in Group 3 did not have an active CL until after ...
Pycock JF, Newcombe JR.The effects on pregnancy rate of three different treatments to remove intrauterine fluid were assessed in 1267 mares. The mares were mated and allocated, in strict rotation, to four treatment groups: 1) untreated controls, 2) intrauterine infusion of broad spectrum antibiotics, 3) intravenous injection of oxytocin, 4) intravenous injection of oxytocin followed by intrauterine antibiotics. The pregnancy status of the mares was determined 13 to 15 days and 27 to 30 days after ovulation by transrectal ultrasonography. The pregnancy rate of group 4 (72 per cent) was higher than that of group 2 (64...
Graham JK.Methodologies to capacitate bovine spermatozoa, induce the acrosome reaction, and fertilize bovine oocytes in vitro have been established. The capability to do the same with stallion spermatozoa, however, is not available. Several different methods have been used to capacitate stallion spermatozoa with variable results. More basic research needs to be done to establish in vitro conditions necessary to capacitate and induce an acrosome reaction in stallion spermatozoa. Although much progress can be expected in this area, it is unlikely that the general practitioner will use these technologies i...
McCue PM.Development of a superovulation technique that is successful, safe, and commercially available would revolutionize the equine breeding industry. However, the reality is that ovulation rates for mares following existing superovulatory treatment are much lower than for cattle. This dichotomy has been attributed to the relatively limited area available in the ovulation fossa for ovulation to occur, combined with the large size of the equine preovulatory follicle. In addition, the number of ovulations in the mare may be limited physiologically by the size of the follicular cohort that may be rescu...
Squires EL, Cook NL.This article describes in detail the procedures for collection of equine oocytes using a transvaginal ultrasound probe. Success in obtaining oocytes from humans, bovines, and horses are presented. The effect of repeated follicular aspiration of both cattle and horses is reviewed.
Dobrinski I, Suarez SS, Ball BA.Interaction of spermatozoa with oviductal epithelial cells (OEC) in the oviductal isthmus prolongs the life span of spermatozoa. The hypothesis that the interaction of equine spermatozoa with OEC affects their intracellular calcium concentration ([Ca2+]i) was tested in a sperm-OEC coculture model. Changes in [Ca2+]i in spermatozoa loaded with the fluorescent calcium indicator indo-1 acetoxymethylester (AM) were determined for spermatozoa attached to OEC or to Matrigel, as well as for free-swimming spermatozoa incubated without oviductal epithelium. [Ca2+]i was determined before incubation and ...
Squires EL.Twinning is a major cause of abortion in mares. Although early management of twins is quite successful, twins that remain after 40 days are difficult to manage. This article reviews the current knowledge of the use of transvaginal ultrasound probe for elimination of twins. Several techniques are presented, as well as discussion on the best time during gestation for this technique to be used.
Veeramachaneni DN, Sawyer HR.Conventional light microscopic evaluation does not fully utilize potential indicators in seminal ejaculates for diagnosis of disorders of the reproductive tract. The technique of evaluation of all cellular components of semen, as described in this article, utilizing both light and transmission electron microscopy is a valuable diagnostic tool. Compare with other common biopsy procedures, use of semen as biopsy material is noninvasive, more representative than excisional biopsy, less expensive, and helps in the longitudinal evaluation after a therapeutic regimen.
Vanderwall DK.Tremendous progress has been made in the development of assisted reproductive techniques that may enhance the reproductive efficiency of the horse. However, techniques that involve the manipulation of oocytes and/or embryos may themselves be detrimental to embryo viability and subsequent development. Therefore, an objective method of assessing viability of embryos before and/or after oocyte/embryo manipulation is desirable. At this time, morphologic evaluation is the most widely used method of determining the viability of equine embryos. Although morphologic assessment of embryo quality will n...
Asari M, Sasaki K, Miura K, Ichihara N, Nishita T.To elucidate locations of cytosolic carbonic anhydrase isoenzyme (CA-I, CA-II, and CA-III)-positive epithelial cells in equine male reproductive organs. Methods: Descriptive and immunohistochemical study. Methods: 4 clinically normal male horses. Methods: The testis (seminiferous tubules, rete tubules), epididymis (initial, middle, and terminal segments), proximal and distal portions of the ductus deferens, ampulla ductus deferentis, seminal vesicle, prostate, and bulbourethral gland were excised from euthanatized horses after administration of an overdose of pentobarbital. The tissue specimen...
Graham JK.This article describes some of the basic methodology for conducting stallion semen evaluations. Not all of these assays will likely be conducted on every semen sample collected. Routine evaluations should include determination of semen volume, sperm concentration, and an estimation of the percentage of progressively motile sperm, at a minimum. Other assays can be used if a seminal problem is discerned at the beginning of the breeding season or after a stallion has recovered from an illness or injury. Additionally, laboratory assays are particularly important to conduct on cryopreserved spermat...
Rodriguez H, Bustos Obregon E.The fertilizing ability of stallion semen was analyzed using fresh and frozen samples, obtained before (June-July) or during (October-November) the breeding season. Thirty ejaculates obtained from 4 stallions were used. The analysis comprises routine seminogram; ATP concentration (Comhaire et al., 1983); subjective and objective motility and sperm velocity (Makler, 1980). Freezing was done following the technique of Martin et al. (1979). Sperm velocity, ATP content and objective motility in ejaculates of subjective motility >50% show values of 14.0 + or - 0.84 mu m s(-1); 4.8 + or - 2.7x10(...
Squires EL.Equine oocytes obtained either by transvaginal ultrasound-guided follicular aspiration or from slaughterhouse ovaries can be matured in vitro. This generally requires culture in TCM-199 containing serum and hormones for 30 to 36 hours. With this protocol, approximately 50% to 60% of the oocytes are at metaphase-II at the end of the culture period. At least some of these oocytes appear viable based on production of fertilized eggs either through in vitro fertilization or fertilization in vivo of a recipient mare. The success of producing equine embryos in vitro is still extremely low. More than...
Brinsko SP.Poor fertility has been associated with hormonal imbalances in the stallion. The primary cause of this imbalance is unknown, but it may be related to abnormal gonadotropin secretion. Secretion of GnRH from the hypothalamus causes the release of LH and FSH from the anterior pituitary and these gonadotropins help maintain adequate steroid levels so that normal spermatogenesis can occur. Hypogonadotropic hypogonadism has not been documented in the stallion; however, GnRH therapy has improved the fertility of a limited number of horses. Downregulation of the HPT axis readily occurs in most other s...
Graham JK.The main advantage to using frozen semen in any breeding program is faster genetic gain for the inherited trait desired. Milk production of dairy cows doubled (from 26,000 to 52,000 kg of milk/cow per year) between 1950 and 1980, because the dairy industry was using semen only from bulls with the greatest genetic potential for milk production. This genetic gain could have been achieved without the use of frozen semen; however, the time required to achieve that same genetic progress would have been lengthened exceedingly. Fertility rates using frozen stallion spermatozoa are not equal to that o...
Martin KL, Hoffman RM, Kronfeld DS, Ley WB, Warnick LD.Changes in serum concentrations of Ca and parathyroid hormone (PTH) may develop in periparturient mares, may be influenced by dietary Ca, and may be associated with changes in Ca concentration of mammary secretion. Milk and blood samples were taken from eight mares on Farm A and eight on Farm B for 10 d before parturition and from four mares on each farm for 5 d postpartum. Milk Ca was measured by two commercial tests. Serum samples were analyzed for PTH and total Ca in 16 mares and for ionized Ca in six (Farm A). Parturition was induced in eight mares on Farm A and four on Farm B; no signific...
Rezai A, Underwood JL, Jalali GR, Mathias S, Allen WR, Mowbray JF.Recurrent spontaneous abortion occurs in 1 in 500 random matings and usually results in abortion of all pregnancies. If absence of antibody to a paternally derived antigen caused abortion, the woman would be expected to make antibody to the other paternal antigen and abort only half her pregnancies. Methods: Microvesicles were prepared from equine placentae. Acid-eluted IgG antibody was eluted from the polymorphic R80K antigen and used to type the residual R80K antigen on vesicles or on peripheral blood leucocytes. Results: In several equine sibships all the half-sibs had the same paternal R80...
Watson ED, Thomson SR.The density and distribution of MHC Class II positive cells and subpopulations of lymphocytes were studied in the endometrium of genitally normal mares and mares susceptible to endometritis. In genitally normal mares, more MHC Class II positive cells were present in the epithelium and stratum compactum during oestrus than dioestrus. Significantly more CD4+ and CD8+ lymphocytes were present in the stratum compactum than in the stratum spongiosum. CD4+ lymphocytes were present in greater numbers than CD8+ lymphocytes in the stratum compactum but approximately equal numbers were present in the st...
Orsini JA, Park MI, Spencer PA.Concentrations of amikacin in endometrial tissue and plasma were studied in mares in estrus after intrauterine infusion of 1.0 or 2.0 g once a day for 3 consecutive d, and after 9.7 or 14.5 mg/kg body weight (BW) had been injected intramuscularly once a day for 3 consecutive d to determine concentrations of amikacin sulfate in plasma and endometrial tissues, and whether parenteral administration provides any advantages over intramuscular infusion. No amikacin was detected in serum at the 1.0 g dose. At the infusion dose of 2.0 g once a day, very low levels of serum amikacin were detected at 1 ...
Pipers FS, Adams-Brendemuehl CS.To establish the feasibility of utilizing high-frequency ultrasound to image equine fetal development transabdominally, in vitro and in vivo observations were made. Three fetuses retrieved from mares that died from various causes were scanned in vitro to establish fetal images from various orientations. A total of 50 mares ranging in age from 4 to 16 years and representing various breeds were scanned intermittently from 100 days of gestation to parturition. Fetal parts, amniotic fluid, placental membranes, and motion patterns could be reliably identified. Fetal heart rates decreased from 180 b...
González-Fernández L, Macedo S, Lopes JS, Rocha A, Macías-García B.Equine in vitro fertilization (IVF) is still inconsistent. In the present work, we studied how modified Whitten's (MW) medium and Tissue Culture Medium 199 (TCM) added with Foetal Bovine Serum (FBS; 10% v/v) or Bovine Serum Albumin (BSA; 7 mg/ml) affected equine gametes to subsequently run IVF trials. Compact (Cp) and expanded (Ex) cumuli equine oocytes were matured and placed in TCM or MW supplemented with BSA or FBS for 18-20 h (no sperm added). In Ex oocytes, TCM-199 added with FBS or BSA resulted in higher metaphase II (MII) rates (75.7% and 62.7%, respectively) than MW added with BSA (54%...
Little TV, Woods GL.The accessory sex glands of 10 stallions were examined by transrectal ultrasonography. Seminal vesicles were 26.4 +/- 5.2 (s.d.) mm in width and 9.2 +/- 3.1 mm in height. Ampullae were 16.3 +/- 3.6 mm in width and 12.9 +/- 3.9 mm in height. Bulbourethral glands were 19.7 +/- 4.6 mm in width and 32.4 +/- 6.7 mm in length. Prostate lobes exceeded 34 mm in width and were 23.5 +/- 5.7 mm in height. The prostatic isthmus was 6.0 +/- 1.4 mm in height. The seminal colliculus, masculine uterus, and deferent ducts were also identified and characterized. Five of these stallions were killed to compare tr...
Chopineau M, Martinat N, Marichatou H, Troispoux C, Auge-Gouillou C, Stewart F, Combarnous Y, Guillou F.Horse LH/chorionic gonadotrophin (eLH/CG) exhibits, in addition to its normal LH activity, a high FSH activity in all other species tested. Donkey LH/CG (dkLH/CG) also exhibits FSH activity in other species, but about ten times less than the horse hormone. In order to understand the molecular basis of these dual gonadotrophic activities of eLH/CG and dkLH/CG better, we expressed, in COS-7 cells, hybrids between horse and donkey subunits, between horse or donkey alpha-subunit and human CG beta (hCG beta), and also between the porcine alpha-subunit and horse or donkey LH/CG beta. The resultant r...
Satué K, Domingo R, Redondo JI.The coordinated interaction of the components of the renin angiotensin aldosterone system (RAAS) with reproductive hormones such as progesterone, oestrogens and cortisol during pregnancy has been widely reported to play a vital role in foetal and placental development in various species, significantly influencing the proper achievement of pregnancy and foetal viability at birth. These interactions have not yet been clarified in mares. Thus, the purpose of the present research was to analyse the relationship between cortisol (CORT), progesterone (P4) and oestrone sulphate (OESTRONE), and the co...
Chopineau M, Martinat N, Gibrat JF, Galet C, Lecompte F, Foulon-Gauze F, Pourchet C, Guillou F, Combarnous Y.To identify amino-acids in the alpha-subunit important for expression of heterospecific FSH activity of horse (e) LH/choriogonadotropin (CG) (eLH) and donkey (dk) LH/CG (dkLH) (FSH/LH ratio ten times higher for eLH than for dkLH); this FSH activity absolutely requires an equid (donkey or horse) alpha-subunit combined with an equid beta-LH subunit. Methods: Chimeric alpha-subunits possessing the first 63 amino-acids of the porcine (p) and the last 33 amino-acids of the donkey alpha-subunit (alphap-dk) and the inverse (alphadk-p) were constructed. Porcine-specific amino-acids were introduced by ...
Dwyer RM, Garber LP, Traub-Dargatz JL, Meade BJ, Powell D, Pavlick MP, Kane AJ.To identify factors associated with excessive proportions of early fetal losses associated with mare reproductive loss syndrome in central Kentucky during 2001. Methods: Case-control study. Methods: Questionnaires were used to collect information on farm-, pasture-, and individual animal-level factors purportedly associated with mare reproductive loss syndrome. Data were collected for 133 farms (97 with excessive proportions of early feta losses and 36 control farms) representing 6,576 mares. Results: Factors significantly associated with an increased risk of excessive early fetal losses were ...
Goretti RG, Araújo RR, Filho AN, Araújo GH, Lopes EP, Guimarães JD.The objective was to evaluate the effects of giving prostaglandin F₂(α) (PGF) to donor mares 48 h prior to embryo collection. Non-lactating donor mares (n = 20 estrous cycles in 10 mares), ranging from 2.5 to 10 y of age and 400 to 500 kg of body weight were used from September 2004 to February 2005 in the southern hemisphere (Brazil). Donor mares were randomly assigned in a cross-over design study. During a Treated cycle, 7.5 mg PGF was given 48 h prior to embryo collection, whereas in the Control cycle, 7.5 mg PGF was given at embryo collection. In Treated Cycles, serum progesterone conce...
Kwong GPS, Klein C.Horses are long-day breeders and commence ovarian follicular activity during the spring. Evidence suggests that there is an endogenous circannual rhythm in mares, and it is uncertain whether hormonal manipulation during or immediately following the fall transition induces follicular development. The current study was designed to test the hypothesis that both deslorelin and naltrexone induce follicular development in late fall transitioning or anestrous mares. Five of six mares treated with deslorelin, and 4 of 6 mares treated with naltrexone, developed a pre-ovulatory-sized follicle and were i...
Miller LMJ, Woodward EM, Campos JR, Squires EL, Troedsson MHT.Sperm protein at 22 kDa has been associated with fertility. Objective: The objectives of this study were to determine (1) the localization pattern of SP22 on ejaculated and caudal epididymal equine spermatozoa and in epididymal fluid, and to (2) characterize SP22 protein and mRNA expression in testicular and epididymal tissues in response to heat-induced testicular degeneration. Methods: Semen was collected before and after hemi-castration, as well as prior to and following insulation of the remaining testes, and tissue specimens were collected for analysis. Results: Histopathology confirmed ...
Ono M, Akuzawa H, Nambo Y, Hirano Y, Kimura J, Takemoto S, Nakamura S, Yokota H, Himeno R, Higuchi T, Ohtaki T, Tsumagari S.A three-dimensional internal structure microscopy (3D-ISM) can clarify the anatomical arrangement of internal structures of equine ovaries. In this study, morphological changes of the equine ovary over the first 12 months of life were investigated by 3D-ISM in 59 fillies and by histological analysis in 2 fillies. The weight and volume of the paired ovaries initially decreased from 0 to 1 months to 2 to 3 months of age and then significantly increased at 8 to 12 months of age. The ovulation fossa was first observed around the 3rd month and became evident after the 6th month. The number of folli...
Salem SE, Sinnott A, Roach JM, Verheyen KLP, de Mestre AM.Multiple pregnancies (MPs) are commonly diagnosed during breeding management of mares. Whilst some studies have reported on factors associated with the risk of MPs, few have utilised multivariable data analysis to control for confounding variables. A prospective cohort study of Thoroughbred broodmares was conducted with information collected on 27 factors. Mixed-effects logistic regression was used to determine risk factors for MPs. Mare, stallion, stud, and veterinarian were evaluated as random effects. The prevalence of MPs in 1754 mares and 2245 pregnancies was 16.06% (95% confidence interv...
Damasceno Teixeira TV, Fry RC, McKinnon A, Fry KL, Kelly JM, Verma PJ, Burden C, Salamone DF, Gambini A.Epigenetic perturbations during the reprogramming process have been described as the primary cause of the low efficiency of somatic cell nuclear transfer (SCNT). In this study, we tested three strategies targeting nuclear reprogramming to investigate effects on equine SCNT. First, we evaluated the effect of treating somatic cells with chetomin, a fungal secondary metabolite reported to inhibit the trimethylation on histone 3 lysine 9 (H3K9 me3). Second, caffeine was added to the culture medium during the enucleation of oocytes and before activation of reconstructed embryos as a protein phospha...
Rosanowski S, Verheyen K.The number of unwanted horses in the UK has increased in recent years. It is therefore important to identify factors that indicate whether a horse can be rehomed and how long it takes to be rehomed. Data from 1 January 2013 until 30 March 2014 were extracted from an equine rehoming charity's database. Exposure variables were examined using multivariable logistic and Cox regression. In total, 791 horses were included in the study and 410 (51.8%) were rehomed during the study period. Median time until rehomed was 39 days (IQR 24-75). Horses whose owner was prepared to transfer ownership were nea...
Marshall DE, Gower DB, Silver M, Fowden A, Houghton E.Equine umbilicus was cannulated in utero and a series of cord plasma samples removed for analysis. After steroid extraction and derivatisation, gas chromatographic-mass spectrometric (GC-MS) analysis demonstrated large differences in steroid content between the plasma samples obtained from the umbilical artery and vein, the blood supplies leading to and from the placental surface, respectively. 3Beta-hydroxy-5,7-androstadien-17-one, dehydroepiandrosterone, pregnenolone, 3beta-hydroxy-5alpha-pregnan-20-one, 5-pregnene-3beta,20beta-diol and 5beta-pregnane-3beta,20beta-diol were identified as maj...
Parker NA, Bailey TL, Bowen JM, Ley WB, Purswell BJ, Dascanio JJ.Like the human female, the mare experiences reproductive tract pathology that may sometimes be circumvented by the use of assisted reproductive technologies (ARTs). One such technology, gamete intrafallopian transfer (GIFT), may be used in mares that exhibit ovulatory, oviductal, or uterine abnormalities that limit the use of common ARTs, such as embryo transfer. Homologous GIFT has been successfully performed in the horse; however, the logistics, costs, and associated risks of surgically transferring gametes to the oviducts of a recipient mare are considerably high. Use of a less costly speci...
Magalhaes HB, Canuto LEF, Canisso IF.The objectives of this study were to determine (i) the usefulness of serial assessment of mammary gland electrolytes concentrations and correspondent pH to detect impending parturition in jennies; and (ii2) the associations between mammary gland secretions, and gestation length, foal sex, maternal, placental, and foal birth weights. Multiparous jennies (n = 37) were monitored daily from 350 to 355 days of gestation until parturition. The pH of mammary gland secretions was assessed daily with a hand-held device. Aliquots of mammary secretions were frozen daily and then retrospectively assesse...
Nogueira GP, Barnabe RC, Verreschi IT.We measured progesterone and estradiol levels from birth to the beginning of adult life in 10 Thoroughbred fillies from the Equilia Stud Farm in Avaré SP, Brasil. The animals were measured and weighed monthly for the determination of body development and of a possible correlation between the rate of weight and height gain and the onset of detectable sex hormone levels. Jugular blood was collected twice a week and stored at -20 degrees C until assay of progesterone by a solid phase RIA with a sensitivity of 0.32 nmol L and of estradiol by liquid phase RIA adapted to low levels (3.67 pmol L ). ...
Turner RM, Love CC, McDonnell SM, Sweeney RW, Twitchell ED, Habecker PL, Reilly LK, Pozor MA, Kenney RM.An 8-year-old stallion was evaluated because of recurrent urinary tract infections and chronic intermittent urospermia. After extensive diagnostic testing, it was hypothesized that the stallion had a reflex dyssynergia of the bladder and urethral sphincter. Initial attempts to manage the urospermia included semen fractionation, semen collection after voluntary urination, and use of semen extenders. None of these efforts reliably yielded a quality ejaculate. Administration of imipramine hydrochloride (1.2 mg/kg of body weight, PO, 4 hours prior to semen collection) was initiated in an attempt t...
Santos VG, Beg MA, Bettencourt EM, Ginther OJ.The effects of inhibition of PGF2α synthesis on luteolysis in mares and on the incidence of prolonged luteal activity were studied in controls and in a group treated with flunixin meglumine (FM), a PGF2α inhibitor (n = 6/group). The FM was given every 8 hours (1.0 mg/kg) on each of Days 14.0 to 16.7. Concentration (pg/mL) of PGF2α metabolite averaged over 8 hours of hourly blood sampling at the beginning of each day, was lower in the FM group than in the controls on Day 14 after ovulation (6.7 ± 1.3 vs. 13.8 ± 2.9, P < 0.05), Day 15 (15.0 ± 3.9 vs. 35.2 ± 10.4, P < 0.10), and Day 16 (21...
Gastal EL, Neves AP, Mattos RC, Petrucci BP, Gastal MO, Ginther OJ.Follicular dynamics were studied during 12 interovulatory intervals (IOIs) and 36 preovulatory periods in Miniature mares. The percentage of IOIs with the following follicle events was: ovulatory wave with only one follicle>or=10 mm (55%), diameter deviation similar to previous reports in larger mares (25%) and minor waves emerging before or after the ovulatory wave (55%). Follicle data were compared among Miniature ponies, large ponies and Breton horses (n=12 IOIs per breed). The IOI was longer (P<0.001) in Miniature ponies (23.3+/-0.9 days) and in large ponies (23.9+/-0.5 days) than in...
Wilsher S, Lefranc AC, Allen WR.Fillies completely devoid of endometrial glands (uterine gland knockout; UGKO) would make ideal experimental models in which to study the role of endometrial histotroph in embryogenesis and early fetal development in the mare. Objective: Administration of a synthetic progestagen plus oestrogen to newborn filly foals and, thereafter, at regular intervals to age 6 months, would permanently suppress endometrial gland development. Methods: Nine half-sister Thoroughbred filly foals were treated, in 3 groups, with: A) the weakly active progestagen, norgestomet, administered from birth to age 6 month...
The Journal of heredityMay 1, 1978
Volume 69, Issue 3 146-148 doi: 10.1093/oxfordjournals.jhered.a108913
Adalsteinsson S.The coat colors of 161 progeny from matings between 10 yellow dun and 6 blue dun stallions and mares of 8 different colors are described. The results confirm the previous hypothesis that a dominant dilution gene, D, converts bay to yellow dun with dark mane and tail, chestnut to yellow dun and dun mane and tail, and black to blue dun (mouse, grullo). The palomino gene, c cr, on the other hand, is hypostatic to black and blue dun. In heterozygous form, c cr converts bay to buckskin, and chestnut and sorrel to palomino, and results in blue-eyed white when homozygous. No particular effect of D is...
Hyland JH, Bristol F.Oestrus was synchronized in 116 mares by means of an i.m. injection of prostaglandin F-2 alpha (Day 0) and of fluprostenol (a PG analogue) on Day 16. Mares were then randomly divided into three groups. Group A mares (N = 30) were given 2500 i.u. hCG I.M. ON Day 20 and artificially inseminated on Day 21 without detection of oestrus. Group B mares (N = 32) were given 2500 i.u. hCG i.m. on Day 20 and inseminated on Days 21 and 23, also without oestrus detection. Group C mares (N = 54) were teased on Days 18, 19, 21, 23 and 25 and inseminated on Days 19, 21, 23 and 25 while they were in oestrus. S...
Aziz DM, Hiss-Pesch S, Mielenz B, Sauerwein H.The study was conducted to determine the baseline concentration of serum haptoglobin (Hp) in jennies during the breeding and nonbreeding season and to evaluate the effects of ovariectomy on serum Hp concentrations in jennies. Eighteen adult jennies were divided in three groups: nine jennies (OVA) were ovariectomized using laparoscopic surgery, six jennies (LAP) were exploratory examined by laparoscopic surgery, and three jennies were used as a control group. Blood samples were collected from the animals at Day -6, -2, -1, 0, 1, 2, 5, 8, 15, 22, 29 and 36 of surgery. Serum samples were analyzed...
Trombetta MF, Accorsi PA, Falaschini A.When the mare's estrous cycle resumes in winter, the β-carotene content of hay is depleted. Sixty Italian trotter mares were randomly assigned to a Control or a Treated Group. Treated Group received 1g/d synthetic β-carotene for 15 days from parturition. Blood samples collected at parturition and on days 5, 10 and 15 after partum were analysed for β-carotene, vitamins A, progesterone, 17 β-estradiol, the energy parameters (glucose, cholesterol, NEFA), the protein profile (total protein, albumin, urea) and LDH. Some changes in these measures were attributable to treatment, which significant...
Anstey SI, Jenkins C, Jelocnik M.Chlamydia psittaci is a recognised cause of late-term equine foetal loss and poses a zoonotic risk in Australia. However, a management strategy is lacking to protect at-risk humans handling infected aborted material and pregnant mares. This study proposes a protocol for approaching C. psittaci foetal loss after investigating four foetal losses that occurred on a horse stud in the Hunter Valley, Australia in 2021. Swabs from the foetal loss cases (n = 4), close contact mares (n = 59), and foals of the close contact mares (n = 33) were collected and tested for C. psittaci using both isothe...
Panzani S, Villani M, Govoni N, Kindahl H, Faustini M, Romano G, Veronesi MC.Hormonal changes during early neonatal life play a major role in the physiological processes underlying the maturation of several organs. Since prostaglandins and cortisol are associated with fetal organ system maturation, the aim of this study was to evaluate 15-ketodihydro-PGF(2alpha) (PGM) and cortisol plasma concentrations during the first 21 days after birth in foals born by either spontaneous (24 foals) or low-dose oxytocin (OT)-induced parturition performed after at least 320 gestational days (25 foals) since induction is often considered to be a cause of prematurity. After spontaneous ...
Alm H, Hinrichs K.The period of protein synthesis necessary for meiotic maturation in horse oocytes initially having compact or expanded cumulus cells was studied. Oocytes incubated in the presence of cycloheximide after 0, 4, 8, 12 or 16 h maturation in vitro (total incubation time 24 h) were matured for 24 h, or were incubated with cycloheximide for 24 h and then matured for 24 h. Incubation with cycloheximide from 0 h was effective in suppressing maturation (no significant increase in maturing oocytes compared with controls fixed directly after removal from the follicle) in both expanded and compact groups a...
Becker F, Kurth J, Schneider F, Nürnberg G, Heinrich H, Kanitz W.The aim of this study was to prove if oxidation-reduction levels in the follicular fluid were new functional indices of follicular health and whether there was a high level of accordance with endocrinological parameters and with the growth stage as detected by ultrasound monitoring of individual follicles during the oestrous cycle in mares. Follicles were classified as growing and regressing follicles using ultrasonography. Altogether 48 follicles with a diameter from 20 to 56 mm were aspirated by transvaginal ultrasound guided follicular aspiration. Follicular concentration of oestradiol and ...
