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.
WIDE M, WIDE L.THE use of a hæmagglutination inhibition reaction for the diagnosis of pregnancy in women was reported by Wide and Gemzell1 and Wide2. In this reaction human chorionic gonadotrophin (HCG) inhibited the agglutination of stable HCG-coated blood cells. The same immunological technique was applied for the assay of pregnant mare serum gonadotrophin (PMS) and was used as a pregnancy diagnosis test in mares. Sera from pregnant mares containing elevated levels of gonadotrophin inhibited an agglutination reaction of PMS-coated formalinized erythrocytes in the presence of PMS anti-serum, while sera fro...
DARLINGTON RW, RANDALL CC.Equine abortion virus was purified from the plasma of infected golden Syrian hamsters by differential centrifugation and nuclease treatment. The preparations were essentially free of nonviral elements on electron microscopic examination, and sedimentation in sucrose and potassium tartrate density gradients resulted in a single visible band. Electron microscopy of this band showed it to be composed of viral particles, and injection into hamsters resulted in infection and death of the animals. The viral particles had a sedimentation coefficient of approximately 2200 S and a hydrated density of 1...
SAXENA BB, McSHAN WH, MEYER RK.Fresh horse-pituitary glands were extracted with 40% ethanol and the gonadotropins were recovered by increasing the alcohol concentration to 85% followed by drying with acetone. This preparation was further extracted with water at pH 5, and the extract was adjusted to pH 7 and lyophilized. The follicle-stimulating hormone in the pH-5-souluble fraction was purified by zone electrophoresis and resolved into six components by starch-gel electrophoresis. One of these components contained follicle-stimulating hormone which was recovered in the elution cell and the contaminating starch was separated...
SHORT RV.A comparison has been made between the steroids present in equine follicular fluid and luteal tissue. Follicular fluid was found to contain progesterone, 17α-hydroxyprogesterone, androstenedione, epitestosterone, 19-norandrostenedione, oestrone, oestradiol-17β and 6α-hydroxyoestradiol-17β, in confirmation of previous studies. On the other hand, luteal tissue contained large amounts of progesterone and 20α-hydroxypregn-4-en-3-one, and a small quantity of 17α-hydroxyprogesterone. No C18 or C19 steroids could be detected.
These findings are therefore interpreted as evidence in favour of ...
SASAKI MS, SASAKI M.In two tissue culture lines, HS and HF, which originated from foetal horse tissues, the changes of chromosomes were studied in the course of serial in vitro transfers. It was found that the two cell lines under consideration were characterized by specific changes in chromosome pattern different from each other. HS underwent transformation from diploidy to hyperdiploidy. HF may have been in a process of transformation from diploidy to tetraploidy. Evidence derived from this study indicates that several courses for chromosome transformation exist, and that generalizations predicting a single pat...
Tekin N, Yurdaydin N, Klug E, Yavas Y, Aksu A, Gülyüz F.Within a German-Turkish university partnership documentation of reproductive data of brood-mares was performed as a part project of the cooperation contract. In the study Arab, Haflinger and cross-breed mares were included. The mares mainly were housed in big studfarms and a smaller part was kept under small private farms. Almost three quarters of both the Arab and Haflinger mares exhibited an estrous length of 1-4 days, whereas the others showed a heat duration of a period of 5-10 days. In the same group of probands a mean length of sexual cycle of 18-24 days could be observed in 38.2% of the...
Dusek J.Inbreeding was used in the regeneration process in the breeding of the Kladrub Black Horse. Inbreeding rate is realized in practice, as related to the manifestation of the selected characteristics of this unique horse population. The evaluation of the effect of inbreeding on conception rate and fertility did not demonstrate any differences between the group of inbred mares and non-inbred mares. The study was conducted in mares used for breeding for 10 years. The results provide evidence that inbreeding causes no depression in this characteristics in the Kladrub Black Horse which would otherwis...
Journée SL, de Ruijter-Villani M, Hendriks WK, Stout TA.Transvaginal ultrasound-guided pregnancy reduction (TUGR) is a procedure described for the management of twins post-fixation in the horse. Success rates are often disappointing but are reported to be more favorable for bilaterally situated twins and when intervention takes place before day 35 of gestation. This study aimed to determine whether stabbing the embryo/fetus rather than aspirating conceptus fluids improved the likelihood of success, measured as the birth of a normal live singleton foal. Data from 103 TUGR interventions were analyzed by logistic regression analysis; method of treatme...
Kojima AY, Kobayashi S, Acosta TJ, Kudo M, Miyamoto A, Takagi M, Miyazawa K, Sato K.Microdialysis System (MDS) is a novel technique used for investigation of molecule secretion between different cell populations. Local hormonal secretion at follicular wall has been still unclear. This MDS study was used to determine progesterone (P4), androstenedione (A4), estradiol-17beta (E2) and Prostaglandin F2alpha (PGF2alpha) release in mare pre-ovulatory follicles. Follicles larger than 30 mm were isolated from the ovary and follicular fluid aspirated for hormone assay. Follicular fluid collected from small, middle and large follicles were analyzed by EIA. The concentrations of P4 and ...
Dynowski J, Wasowska-Królikowska K, Modzelewska-Hołyńska M, Tomaszewska M, Funkowicz M.Atopic dermatitis is a disease of multifactorial pathogenesis. Objective: of the study was to establish the most common allergens responsible for development of atopic symptoms in children with atopic dermatitis. Methods: the study complied 36 children aged 4 months - 3 years treated in the Department of Children Allergology, Gastroenterology and Nutrition because of atopic dermatitis. With each case the patient and family history of atopy was collected and basic laboratory tests were conducted (including total IgE and specific IgE using Polly Check system). Results: eosinophilia was found in ...
Oprescu SV.The paper presents the results of some genetic studies accomplished in Romania in the field of pathology of reproduction in domestic animals (pseudohermaphroditism in horses, testicular hypoplasia in he-goats, intersexuality in pigs, freemartinism and genital infantilism in cattle). Also, the use of the cytogenetic test in genetic prophylaxis in pigs and cattle was shown. In addition, the methods for detecting genitors with undesirable genes were devised and perspectives for the development of hereditary hygiene discussed.
McCue PM, Matthews PM, Prell MJ, Bellone RR, Allen H.Genetic testing is required for the registration of foals of most equine breeds. Objective: To describe two clinical cases of marked delayed embryonic development or delayed fertilisation in pregnancies generated by embryo transfer. Methods: Case report. Methods: Donor mares were inseminated with semen from one stallion during one oestrous cycle and semen from a different stallion on the subsequent oestrous cycle. Embryo(s) were collected 8 days after ovulation during the second oestrous cycle and transferred into synchronised recipient mares. Genetic testing was performed to determine paren...
Meintjes M, Graff KJ, Paccamonti D, Eilts BE, Paul JB, Thompson DL, Kearney MT, Godke RA.When aspirating ovarian follicles in pregnant mares to obtain oocytes for in vitro fertilisation (IVF), the effect of the manipulation on circulating concentrations of progesterone may be an important consideration in terms of the maintenance of pregnancy. The object of this study was to compare the effects of 3 different forms of transvaginal ultrasound-guided follicle aspiration (Treatment 1, no aspiration, n = 4; Treatment 2, aspirate only follicles > or =20 mm in diameter, n = 7; Treatment 3, aspirate all visible follicles, n = 7) on peripheral plasma progesterone concentrations between Da...
Liu S, Lian S, Yang Y, Fu C, Ma H, Xiong Z, Ling Y, Zhao C.An experiment was conducted to study the association between the single nucleotide polymorphisms (SNPs) in 5'-untranslated regions (5'-UTR) of equine chorionic gonadotropin (eCG) genes and the serum eCG levels. Methods: SNPs in 5'-UTR of eCG genes were screened across 10 horse breeds, including 7 Chinese indigenous breeds and 3 imported breeds using iPLEX chemistry, and the association between the serum eCG levels of 174 pregnant Da'an mares and their serum eCG levels (determined with ELISA) was analyzed. Results: Four SNPs were identified in the 5'-UTR of the eCGα gene, and one of them was u...
Numata M, Kondo T, Nambo Y, Yoshikawa Y, Watanabe K, Orino K.Antibody (immunoglobulin G (IgG), IgM or IgA) levels relative to ferritin in six foal sera (three male and three female) after birth (day 0 and 2, 6, 10, 20, 28, 36, 40, 52 and 56 weeks of age) were semi-quantitatively measured with normalization with antibody activity to ferritin in one adult horse serum. After addition of horse spleen ferritin to the serum sample, the complex formed between antibodies to ferritin in the serum and ferritin was co-immunoprecipitated using antibody to horse spleen ferritin. Antibody classes of the co-immnoprecipitate were detected with antibodies specific for h...
Held JP, Prater P, Stettler M.A 9-year-old Arabian stallion with a 3-year history of infertility was evaluated for breeding soundness. Both testes were small. Ultrasonography revealed a small amount of free fluid between the tunics of both testes. Results of cytologic examination of the fluid were unremarkable. On semen examination, progressive motility was 10%, and total number of spermatozoa in the ejaculate was 6.6 x 10(9), of which 92% were abnormal. Predominant abnormalities were head defects (75%): 57% of the heads had single or multiple vacuoles, and 60% also had midpiece swelling or bending.
Brasileiro LS, Segabinazzi LGTM, Menezes E, Salgueiro CC, Novello G, Scheeren VFDC, Alvarenga MA, Nunes JF.The aim of this study was to evaluate the effect of coconut water as a component of extender in different formulations for cooling equine sperm. One ejaculate of fourteen stallions was collected. Sperm was diluted to 50 × 10 sperm/mL using five different extenders: ACP-105: powdered coconut water extender (ACP-105, ACP Biotecnologia, Brazil); ACP-Milk: ACP-105 + 20 g/L of skimmed milk; ACP-EY 2.5%: ACP-105 + 2.5% of egg yolk; ACP-EY 5%: ACP-105 + 5% of egg yolk; and BotuSêmen (Botupharma, Botucatu, Brazil) and cooled in passive cooling device (BotuFlex, Botupharma, Botucatu, Brazil) at 5...
Solti L, Eulenberger K, Kurth D, Schöne L.Anoestrous mares were treated with prostaglandin (n = 43) and those that did not respond to prostaglandin (n = 29) with a synthetic progestagen, allyloestrenol, at a dose of 0.05 mg/kg body mass for 12 days. After the cessation of the long-term per os gestagen blockade the animals were checked for heat and, if a preovulatory follicle could be palpated, 2000 IU hCG was administered to induce ovulation. In some animals the plasma 17 beta-oestradiol (E2) and progesterone (P4) levels were also followed up throughout the gestagen treatment and for 10-14 days thereafter. As the favourable oestrus ra...
Hüthwohl H, Weiss R, Schmeer N, Schliesser T.Classification based on biochemical characteristics of 389 strains of plasma-coagulase-negative (plc-) staphylococci isolated from the genital tract of mares and stallions resulted in the following distribution of species: St. sciuri 130 (33.4%), St. equorum 42 (10.8%), St. xylosus 16 (4.1%), St. epidermidis 35 (9.0%), St. simulans 24 (6.2%), St. haemolyticus 33 (8.5%), St. warneri 18 (4.6%), St. lentus 12 (3.1%), St. hyicus 11 (2.8%). Strains of St. cohnii, St. capitis, St. gallinarum, St. saprophyticus and St. hominis have only been found sporadically (a. 1%). 48 (12.3%) strains could not be...
Evans TJ, Ganjam VK, Miller MA, Niswender KD, Krause WJ, Youngquist RS.Endometrial periglandular fibrosis (EPF) has been proposed as a possible aetiology for equine embryonic and fetal loss. However, the pathophysiology of EPF is not well understood. Angiotensin-converting enzyme (ACE) is found in macrophages, endothelium (during angiogenesis) and myofibroblasts at sites of fibrosis in the heart, kidneys, liver and skin in several species. An increase in local tissue ACE-binding activity appears to be a critical event in the initiation and progression of fibrosis in these tissues. The aim of this study was to investigate the correlation between ACE activity in th...
Roth TL, White KL, Thompson DL, Barry BE, Capehart JS, Colborn DR, Rabb MH.In this experiment we have identified and partially characterized the immunosuppressive activity of preimplantation horse conceptus-conditioned medium (HCCM). Horse conceptuses were nonsurgically flushed from mares at Days 9-10 (n = 6), 15-16 (n = 3), and 25-26 (n = 3). After incubating the conceptuses for 24 h in RPMI-1640 supplemented with 15% fetal calf serum (FCS) and 1% penicillin/streptomycin, HCCM was obtained from cultures and tested for immunosuppressive activity in lymphocyte proliferation assays. Peripheral blood lymphocytes obtained from randomly selected mares were stimulated with...
de Moura TCM, Arruda LCP, Cahú TB, Bezerra RS, Carneiro GF, Guerra MMP.Semen cryopreservation ensures the storage of stallion genetics for an unlimited time. The improvement of extenders with new antioxidant substances can optimize the properties of post-thawed semen. The study aimed to investigate the addition effect of medium-molecular-weight carboxymethylchitosan (CQm) derivates to freezing diluent of stallion sperm after freezinf/thawing. Twice a week, five ejaculates of four stallions were obtained, totalizing 20 ejaculates. Semen was diluted in commercial freezing extender (Botucrio) supplemented with CQm: control (0), 0.75, 1.5, and 3 mg/mL. Samples were ...
Boye JK, Bulkeley EA, Dujovne GA.To describe uterine prolapse, predispositions, and outcomes in mares treated between 1988 and 2019. 24 mares with uterine prolapse. Clinical records were retrospectively reviewed, and follow-up information was gathered. The Mann-Whitney U test and Fisher exact test were used to analyze results for history and outcome variables for potential association with mare survival to hospital discharge. The χ2 test was used to compare breed distribution. Age was known in 23 mares (median, 11.1 years). For 15 mares with exact known parity, the median parity was 3 births (range, 1 to 13 births). For 22 m...
Boye JK, Katzman SA, Kass PH, Dujovne GA.In equids, it is common to inject lidocaine into the testicles at the time of routine castration to provide analgesia. The effects of lidocaine on equine sperm have not been evaluated in vitro or on epididymal sperm collected following castration. The aims of this study were to determine effects of clinically relevant doses of lidocaine on equine spermatozoa in vitro using freshly collected semen and to compare the characteristics of epididymal spermatozoa after routine castration with or without intra-testicular lidocaine administration. We hypothesized that increasing concentrations of lid...
Dietz JP, Sertich PL, Boston RC, Benson CE.Ticarcillin and piperacillin were compared to determine their effect on sperm motility and bacterial growth of equine semen samples diluted in Kenney's glucose skim milk semen extender. Each ejaculate (n=11) was divided into three portions and glucose skim milk semen extender solution was added. The control semen extender solution contained extended semen and no antibiotic, whereas ticarcillin and piperacillin solutions contained extended semen plus 1.0mg/mL of ticarcillin or piperacillin, respectively. An aliquot was removed (1h after collection) to evaluate sperm motility and microbial conce...
Gee EK, Gillespie L, Bolwell CF.To compare the efficacy of oxytocin given once daily, either I/V or I/M, on Days 7-14 post-ovulation, on the expression of oestrus in mares through to 65 days post-ovulation. Methods: Eighteen mares of various breeds that were displaying normal oestrous cycles were randomly assigned to one of three treatment groups on the day of ovulation (Day 0), detected using transrectal ultrasonography. Mares in the control group (n = 6) were given 1 mL saline I/V; mares in the I/V and I/M groups (n = 6 per group) were injected with 10 IU oxytocin I/V and I/M, respectively. All treatments were given once d...
Vanderwall DK, Betschart RW, Squires EL.The objective of this study was to determine if the primary circulating metabolite of PGF2alpha, 13,14-dihydro-15-keto-PGF2alpha (PGFM), is biologically active and would induce luteolysis in nonpregnant mares. On Day 9 after ovulation, mares (n = 7/group) were randomly assigned to receive: 1) saline control, 2) 10 mg PGF2alpha or 3) 10 mg PGFM in 5 mL 0.9% sterile saline i.m. On Days 0 through 16, blood was collected for progesterone analysis. In addition, blood was collected immediately prior to treatment, hourly for 6 h, and then at 12 and 24 h after treatment for progesterone and PGFM analy...
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...
Wang X, Kole AR, Greenwald GS.This study was designed to determine whether the major site of eCG neutralization by an antiserum to the hormone is at the peripheral or ovarian level. Hamsters hypophysectomized at oestrus were injected s.c. with 25 iu eCG. Three days later, preovulatory follicles were dissected and cultured for 5 h and the medium was changed every hour. At the end of the first hour of incubation, oestradiol and androstenedione accumulation was high, with a sharp drop over the next 4 h, whereas progesterone concentrations did not change over the entire period. Addition of eCG antiserum to the incubated follic...
Joonè CJ, Cavalieri J.There is a need for a safe, effective and practical method of oestrus suppression in the mare. The aim of this study was to monitor ovarian activity in mares exposed to either 9.4 or 28.2 mg deslorelin acetate, a GnRH agonist, in the form of a sustained-release implant. Following oestrus synchronisation, mares were randomly assigned to one of three groups (n = 4 per group) and administered either one (Des1 group; 9.4 mg) or three (Des3 group; 28.2 mg) implants of deslorelin acetate (Suprelorin-12, Virbac Australia) or one blank implant (Control group; Virbac Australia). Mares underwe...
Ginther OJ, Bergfelt DR.Seasonally anovulatory mares were injected, i.m., twice daily with a GnRH analogue (GnRH-A), and hCG was given when the largest follicle reached 35 mm in diameter. In Exp. 1, treatment was initiated on 23 December when the largest follicle per mare was less than or equal to 17 mm. An ovulatory response (ovulation within 21 days) occurred in 17 of 30 (57%) GnRH-A-treated mares on a mean of 15.8 days. The shortest interval to ovulation in control mares (N = 10) was 57 days. The diameter of the largest follicle first increased significantly 6 days after start of treatment. In Exp. 2, treatment wa...
Hohenhaus MU, Bostedt H.108 mares with a total of 135 oestrous cycles were examined. 30% of the mares showed development of double follicles, found by palpation and ultrasonography. Eight cases of double ovulation, four of them synchronous and four asynchronous, were examined closely. These cases of double ovulation showed different growth and different development of the follicular wall. This occurred at the same time in cases of synchronous double ovulation whereas it differed in case of asynchronous double ovulation. The later ovulating follicle was still growing while the first one had already burst. With both fo...
Krohn J, Ennen S, Hospes R et al. Use of a cervical stent for long-term treatment of pyometra in the mare: A report of three cases. Reprod Dom Anim 2019; 55: 1155–1159 DIE PYOMETRA DER STUTE IST EIN CHRONISCHER ENTZüNDUNGSZUSTAND DES ENDOMETRIUMS, DER HäUFIG MIT DER AKKUMULATION GROßER MENGEN AN SEKRET EINHERGEHT. PRäDISPONIERT SIND STUTEN MIT VERäNDERUNGEN DER ZERVIX, DURCH DIE DIE UTERINE CLEARANCE BEEINTRäCHTIGT WIRD. DIE HäUFIG UNSPEZIFISCHEN SYMPTOME UMFASSEN LEISTUNGSMANGEL, KONDITIONSVERLUST, SUBFEBRILE TEMPERATUR ODER KOLIKARTIGE SCHMERZEN. MANCHE TIERE PRäSENTIEREN SICH SYMP...
Brück I, Bézard J, Baltsen M, Synnestvedt B, Couty I, Greve T, Duchamp G.In mares, the shortage of oocytes and the variability in nuclear maturation at a certain time of the oestrous cycle hinders the optimization of methods for in vitro maturation and in vitro fertilization. Increasing the number of small-to-medium-sized follicles available for aspiration in vivo may increase the overall oocyte yield. The aims of the present study were to investigate whether administration of crude equine gonadotrophins affects follicular development, oocyte recovery rate, in vivo oocyte maturation and follicular concentrations of meiosis-activating sterols. During oestrus, all fo...
Rigby S, Love C, Carpenter K, Varner D, Blanchard T.Eleven light-breed pregnant mares (335 to 347 d gestaton) were used to evaluate the use of prostaglandin E2 as a cervical ripening agent prior to induction of parturition during the months of April and May. Six hours prior to induction, each mare's cervix was examined per vagina for softness and dilation. Each mare was then assigned to 1 of 2 treatment groups: Group PGE mares (n = 7) received 2.0 to 2.5 mg prostaglandin E2 deposited intracervically; Group SAL mares (n = 4) received 0.5 mL of sterile NaCl deposited intracervically. Six hours later, the mares were readied for parturition by wrap...
