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.
Neuhauser S, Bollwein H, Siuda M, Handler J.Cryopreservation of epididymal sperm allows the saving of genetic material in case of unexpected death or emergency castration. The aim of the present study was the comparison of five different combinations of extenders commercially available for equine frozen semen processing for cryopreservation of epididymal sperm. Epididymal sperm were harvested from gonads of 10 healthy stallions after routine castration by retrograde flush technique. Then, samples were split and diluted with (1) INRA96 + INRA Freeze, (2) BotuSemen + BotuCRIO, (3) EquiPlus + Gent Freeze, (4) EquiPlus + EquiPlus Freeze...
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...
Castillo JM, Tse MPY, Dockweiler JC, Cheong SH, de Amorim MD.A 16-year-old Oldenburg mare was evaluated for stallion-like behavior. The mare had given birth to 2 foals previously. Transrectal palpation revealed bilaterally enlarged ovaries with no palpable ovulation fossa. Ultrasound examination showed both ovaries to have small follicles giving a honeycomb appearance, concurrent with a single large cystic structure in the left ovary (10.2 cm diameter). Serum Anti-Müllerian hormone (AMH) was elevated (95.7 pmol/L), consistent with granulosa cell tumor (GCT). Both ovaries were removed via flank laparoscopy and were evaluated by histopathology, which con...
Mitchell ARM, Delvescovo B, Tse M, Crouch EE, Cheong SH, Castillo JM, Felippe MJB, Ainsworth DM, de Amorim MD.A 6-year-old Standardbred mare was presented at 339 days of gestation for investigation of abnormal abdominal distension and ventral edema. Transrectal palpation and ultrasound examination revealed the uterus to be enlarged with an excessive volume of fetal fluid, characteristic of hydrops. Gradual transcervical drainage of 55 L of allantoic fluid over 45 minutes, with concurrent intravenous fluid therapy followed by assisted vaginal delivery, resulted in the birth of a live foal with long-term survival. The birth and long-term survival of a foal from a mare with hydrallantois at term has not ...
Neuhauser S, Handler J, Schelling C, Pieńkowska-Schelling A.Chromosomal abnormalities are notable causes of infertility in horses. Mares show various degrees of estrous behavior, and ultrasound examination often reveals an underdeveloped genital tract. This article reports investigations on fertility in a Haflinger sibship with a healthy, normally developed, fertile mare with at least three healthy offspring. Chromosomal analysis performed incidentally and blinded for this mare revealed 63,X/64,XX/65,XXX mosaicism. Two closely related mares were also mosaics (63,X/64,XX), and one of them was a carrier of a marker chromosome. Repeated examinations of th...
de la Torre J, Crespo F, Arroyo F, Zabal-Aguirre M, Abdoon AS, Gosálvez J.Artificial insemination programs for horses usually involve ex vivo handling and transporting of sperm. The present experiment was designed to: (i) assess the effect of transportation on sperm DNA integrity at different time post semen collection, and (ii) evaluate if sperm DNA quality deteriorates rapidly beyond 24 h of cooled storage. After collection, the ejaculates were extended using INRA 96 and semen was prepared for prompt analysis (A0) or 24 h/48 h cooled-shipping (B24 and C48 respectively). Each sample was assessed for sperm DNA fragmentation index (SDFI) at time 0 and after inc...
Martinez de Andino EV, Brom-de-Luna JG, Canesin HS, Rader K, Resende HL, Ripley AM, Love CC, Hinrichs K.To assess meiotic and developmental competence after transfer of immature cumulus-oocyte complexes (COCs) to the preovulatory follicles of mares (intrafollicular oocyte transfer (IFOT)). Methods: In Experiment 1, mares received an ovulatory stimulus at IFOT. Thirty hours later, COCs were recovered from the follicle, and mature oocytes underwent ICSI and embryo culture. In Experiments 2 and 3, autologous vs. allogeneic COCs were used. The mares were inseminated and embryos were recovered. In Experiment 3, the ovulatory stimulus was administered 9 h (autologous) and 15 h (allogeneic) before IF...
Anderson JA, Alves DA, Cerqueira-Cézar CK, da Silva AF, Murata FHA, Norris JK, Howe DK, Dubey JP.Neosporosis is a common cause of abortion in cattle worldwide but is rare in horses. Here, the first case of histologically, ultrastructurally, immunohistochemically, and molecularly confirmed equine abortion caused by neosporosis is reported. Samples of lung, heart, liver, skeletal muscle, tongue, brain, and the placenta from a female fetus aborted at 280 days of gestation were fixed in formalin and submitted for diagnosis. Histologically, there was disseminated neosporosis with severe lesions in lungs, liver and the heart. Protozoal tachyzoites in all tissues reacted with polyclonal anti-Neo...
Legacki EL, Bal BA, Corbin CJ, Loux SC, Scoggin KE, Stanley SD, Conley AJ.The authors apologize for errors in Figure 6 of their article published in the October 2017 issue of Reproduction (vol 154 iss 4 pp 445–454). The authors explain that the addition of data (Figure 6) on steroid concentrations in the chorioallantois to their manuscript on fetal adrenal and fetal gonadal steroids during development of the equine fetus was made in response to reviewer comments. However, in compiling, summarizing and graphing the data, the wrong units were used in the final figure. The manuscript as published represents the data in Figure 6 as “ng/g”, when in fact they are ...
Pietrani M, Losinno L, Cuervo Arango J.In the present study, 2.228 cycles of 180 Polo Argentino donor mares from an embryo transfer program in Argentina were examined to evaluate the effects of: (1) Interval from Prostaglandin F2alpha analog treatment to ovulation (ITO) on embryo recovery rate (ERR); (2) ITO on number of embryos per flushing (EPF); (3) ITO on multiple ovulation (MO) rate; (4) ITO from donor mare on pregnancy rate (PR) in recipient mares. Mares were inseminated with fresh semen from 31 fertile stallions in the induced estrus. Embryo flushing was performed 7-8 days postovulation. Following embryo flushing, donor mar...
Negi NJ, Swanberg JE, Clouser JM, Harmon-Darrow C.The American agricultural industry is heavily reliant on Latina/o workers, yet there is scant understanding regarding the mental health of this population. This gap in the literature is glaring as Latina/o farmworkers are a highly vulnerable group who experience high rates of occupational risks and health hazards. This study is the first, to our knowledge, to examine individual, social and work-related correlates of depression among Latina/o horse workers. Methods: A community survey ( = 225) administered by lay health workers was implemented with Latina/o horse workers who were employed in th...
Ghallab ARM, Abou-Ahmed MM, Fad AM, El-Badry DA, Shahat AM, Moawad AR.Cryopreservation of Arabian stallion semen is important in order to improve the function and fertility of frozen/thawed semen in this breed. Objective: To investigate the effects of centrifugation, type of semen extenders, and type of cryoprotectants on the quality of frozen/thawed Arabian stallion spermatozoa. Methods: Semen samples collected from four adult Arabian stallions (one ejaculate per week for 10 consecutive weeks) were either processed directly without centrifugation (no centrifugation; NC) or subjected to centrifugation on the gel-free fraction. Centrifugation protocols were divid...
Robles M, Couturier-Tarrade A, Derisoud E, Geeverding A, Dubois C, Dahirel M, Aioun J, Prezelin A, Calvez J, Richard C, Wimel L, Chavatte-Palmer P.Foals born to primiparous mares are lighter and less mature than those born to multiparous dams. Factors driving this difference are not totally understood. Using 7 multiparous and 6 primiparous standardbred mares, we demonstrated that, in late gestation, primiparous mares were less insulin resistant compared to multiparous mares, and that their foals had reduced plasma amino-acid concentrations at birth compared to foals born to multiparous mares. Vascular development, as observed through structure and gene expression, and global DNA methylation were also reduced in primiparous placentas. Ano...
Ortiz-Rodriguez JM, Martín-Cano FE, Ortega-Ferrusola C, Masot J, Redondo E, Gázquez A, Gil MC, Aparicio IM, Rojo-Domínguez P, Tapia JA....Oxidative stress is considered a major mechanism causing sperm damage during cryopreservation and storage, and underlies male factor infertility. Currently, oxidative stress is no longer believed to be caused only by the overproduction of reactive oxygen species, but rather by the deregulation of redox signaling and control mechanisms. With this concept in mind, here, we describe for the first time the presence of the soluble carrier family 7 member 11 (SLC7A11) antiporter, which exchanges extracellular cystine (Cyss) for intracellular glutamate, in stallion spermatozoa, as well as its impact ...
To T.A 15-year-old thoroughbred non-pregnant mare was presented with ongoing inappropriate lactation. The most likely cause, equine Cushing's disease, was ruled out through biochemical testing. Milk cytology and bacterial culture showed no evidence of mastitis or neoplasia. Idiopathic inappropriate lactation was diagnosed and treatment with pergolide was recommended. Lactation inappropriée chez une jument Pur-sang âgée de 15 ans. Une jument Pur-sang non gravide âgée de 15 ans a été présentée avec une lactation continue inappropriée. La cause la plus probable, la maladie de Cushing, a ét...
Minkwitz C, Schoon HA, Zhang Q, Schöniger S.Equine endometrosis, a frequent cause of subfertility, is characterized by periglandular fibrosis, and no treatment exists. Endometrial biopsies not only contain diseased glands, but also contain healthy glands and stroma. Myoepithelial (ME) and myofibroblastic (MF) markers are calponin, smooth muscle actin (SMA), desmin and glial fibrillary acidic protein (GFAP). Epithelial vimentin expression indicates epithelial to mesenchymal transition (EMT). The aim of this immunohistochemical study was to investigate whether biopsies with endometrosis express MF and ME markers and vimentin. Compared to ...
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...
Hannan MA, Murase H, Sato F, Tsogtgerel M, Kawate N, Nambo Y.The peripheral blood concentrations of insulin-like peptide 3 (INSL3) have been detected in many mammalian species, but the level of INSL3 in horse remains unknown. The objectives were to develop a time-resolved fluorescence immunoassay (TRFIA) to detect INSL3 concentrations from horse blood as well as to determine the age-related and seasonal changes of plasma concentrations of INSL3 and testosterone from birth to early-puberty in Thoroughbred male horse (n = 11). Monthly blood sample and measurement of body weight, height, chest and cannon bone size were done from birth until 16 mo. Th...
Pinna AE, Okada CTC, Ferreira CSC, Campos DG, Possidente KS, de Cássia C L Morais R, Oliveira M, Salomão MC, Hataka A.Ovarian tumours in mares represent 2.5% to 6% of the most frequent neoplasms found in the equine species, with a higher chance of benignity. This study aims to describe a case of two different tumours found in the same ovary of a mare that presented clinical signs of suppressed oestrous cycle during 5 years. After unilateral ovariectomy, the ovary was sent to the histopathology examination which determined a mixed tumour of granulosa cell and leiomyosarcoma. After treatment, the mare returned to oestrus and got pregnant in the next season.
Caballeros JE, Camacho C, Cazales N, Estradé MJ, Fiala-Rechsteiner S, Jobim MIM, Mattos RC.Rapid endometrial adaptations occur with the embryo entering the uterus to create a receptive uterine environment, which is essential for the conceptus' development. The aim of this study was to demonstrate ultrastructural and histological changes of the endometrium at day 5 after ovulation in cyclic and inseminated mares. Mares were daily examined by transrectal palpation and ultrasonographic examination of the reproductive tract until ovulation was detected. In the first cycle, endometrial biopsies from 10 cyclic mares (Cyclic group) were collected on day 5 post-ovulation. In the second cycl...
Ducheyne KD, Rizzo M, Daels PF, Stout TAE, de Ruijter-Villani M.Vitrified-warmed immature equine oocytes are able to complete the first meiotic division, but their subsequent developmental competence is compromised. Therefore, the present study investigated the effects of vitrifying immature horse oocytes on the chromosome and spindle configuration after IVM. Cumulus-oocytes complexes (COCs) were collected and divided into two groups based on mare age (young ≤14 years; old ≥16 years). COCs were then either directly matured invitro or vitrified and warmed before IVM. Spindle morphology and chromosome alignment within MII stage oocytes were assessed usin...
Legacki EL, Scholtz EL, Ball BA, Esteller-Vico A, Stanley SD, Conley AJ.Few studies have provided a longitudinal analysis of systemic concentrations of conjugated oestrogens (and androgens) throughout pregnancy in mares, and those only using immunoassay. The use of liquid chromatography tandem mass spectrometry (LC-MS/MS) will provide more accurate concentrations of circulating conjugated steroids. Objective: To characterise circulating concentrations of individual conjugated steroids throughout equine gestation by using LC-MS/MS. Methods: Longitudinal study and comparison of pregnant mares treated with vehicle or letrozole in late gestation. Methods: Sulphated oe...
Sales F, Ferreira-Silva J, Vieira J, Basto S, Filho P, Rocha J, Moura MT, Oliveira M.Post-diluents could potentially increase semen cryotolerance, but remain poorly explored in horses. The aim was to evaluate the efficiency of post-diluents on frozen-thawed semen viability of two stallions (S1-S2). The cryopreserved semen was thawed at 50°C for 40 seconds. Semen motility and acrosin activity (AA) were determined during the thermo-resistance test (TRT). Progressive motility of S2 semen decreased after 60 and 90 minutes of TRT (TRT60 and TRT90) on the control compared to both post-diluents. The total motility of both S1 and S2 decreased on TRT60 and TRT90 semen control versus b...
Martins HS, Martins-Filho OA, Araujo MS, Martins NR, Lagares MA.Frozen equine semen has lower fertility compared to cooled semen. Due to the difficulty to obtain equine oocytes, a heterologous zona pellucida binding assay (ZBA) is an alternative method to predict the fertilizing capability of equine frozen sperm. The rate of capacitated and hyperactivated sperm according to their motility characteristics were analyzed with a Computer Assisted Sperm Analyzer. We believe this report describes for the first time the in vitro hyperactivation induction and the heterologous ZBA to predict the fertilizing ability of frozen equine sperm. Objective: This work aimed...
Ginther OJ, Domingues RR, Kennedy VC, Dangudubiyyam SV.An inhibitor of PGF2α biosynthesis (flunixin meglumine, FM) was used to study the role of endogenous PGF2α on the luteolytic effect of exogenous PGF2α in mares. A 2-h infusion of PGF2α at a constant rate (total dose, 0.1 mg) on Day 10 (ovulation = Day 0) was used to mimic the maximal concentrations of a spontaneous pulse of a PGF2α metabolite (PGFM). Treatment with FM (1.7 mg/kg) was done 1 h before and 5 h after the start of PGF2α infusion. In hourly blood samples beginning 1 h before the start of PGF2α infusion, progesterone decreased (P < 0.05) similarly by 5 h in each of t...
Cuervo-Arango J, Claes AN, Stout TA.Advancing maternal age is known to negatively affect fertility in the horse. This age-related decrease in fertility has been linked primarily to reduced oocyte quality rather than to impaired uterine function. In the past decade, the use of ovum pick-up (OPU) and ICSI to produce foals has rapidly gaining popularity amongst sport horse breeders. However, it is not yet known how maternal age influences the efficiency of a commercial OPU-ICSI program and whether the age effect is similar to that observed for other ART in the horse. To answer this question, reproductive records of 289 mares bred b...
Hawkes M, Richard A, Oldfield C, Toothaker A, Stokes M, Causey R.Postbreeding bacterial uterine infections inflict major losses on the equine industry. Microcurrents propelled by ciliated cells between the folds of the uterus and cervix have been proposed as a means by which contaminants are expelled. Previous data have shown possible ciliary microcurrents propelling carbon particles, occasionally rotating, through cervical folds. However, adherence to the epithelium may have interfered with movement of carbon in these studies. Therefore, we tested potentially nonadherent substances to reveal ciliary microcurrents on the equine cervix under high magnificati...
Loux SC, Fernandes CB, Dini P, Wang K, Wu X, Baxter D, Scoggin KE, Troedsson MHT, Squires EL, Ball BA.Intrauterine infection and inflammation remain a major cause of preterm labour in women and mares, with little known about small RNA (sRNA) expression in tissue or circulation. To better characterise placental inflammation (placentitis), we examined sRNA expression in the endometrium, chorioallantois and serum of mares with and without placentitis. Disease was induced in 10 mares via intracervical inoculation of Streptococcus equi ssp. zooepidemicus, either with moderate or high levels of inoculum; three uninoculated gestationally matched mares were used as controls. Matched chorioallantois an...
Delerue M, Breuil MF, Duquesne F, Bayon-Auboyer MH, Amenna-Bernard N, Petry S.Taylorella equigenitalis can be transmitted during artificial insemination. This report describes clinical T. equigenitalis transmission by cryopreserved stallion semen. T. equigenitalis isolates from a mare's vaginal discharge and semen from the same batch of the cryopreserved semen used for the insemination gave identical API ZYM, antibiotic susceptibility, and multilocus sequence typing results (ST-46); furthermore, the multilocus sequence typing lineage ST-46 is known to circulate in the country of semen collection. These results support the need for strict contagious equine metritis scre...
Salem SE, Hough R, Probert C, Maddox TW, Antczak P, Ketley JM, Williams NJ, Stoneham SJ, Archer DC.Periparturient mares are at increased risk of colic including large colon volvulus, which has a high mortality rate. Alterations in colonic microbiota related to either physiological or management changes, or both, that occur at this time have been suggested as potential causes for increased colic risk in this population of horses. Although the effect of management changes on the horse faecal microbiota has been investigated, limited work has been conducted to investigate changes in faecal microbiota structure and function in the periparturient period. The objectives of the current study were ...
Chandley AC, Fletcher J, Rossdale PD, Peace CK, Ricketts SW, McEnery RJ, Thorne JP, Short RV, Allen WR.Chromosomal abnormalities have been detected in seven mares isolated by their poor reproductive performance. All had small or rudimentary gonads and absent or irregular oestrous cycles. Two mares had an XO genotype, one was a 65,XXX female and another a 64,XY sex-reversed female. Two other mares were sex chromosome mosaics of the 63,X/64,XX type. The seventh mare showed a normal female karyotype but a small extra autosomal fragment was found in a few cells.
Köhne M, Kuhl J, Ille N, Erber R, Aurich C.For prevention of early conceptus loss in the horse, treatment with progestins has become common practice. In cattle, treatment with human chorionic gonadotrophin (hCG) during the early postovulatory phase stimulates endogenous progesterone synthesis, which is an important factor for maintenance of early pregnancy via stimulation of endometrial function and conceptus development. In the present study we have therefore investigated the influence of treatment with hCG either for induction of ovulation or during the early luteal phase on plasma progestin concentrations, size of the corpus luteum ...
Hurtgen JP.The breeding soundness evaluation of a stallion is a thorough investigation of a stallion's libido, mating ability, and semen quality. The evaluation should include historical data about the medical aspects of the horse's performance and breeding career, observations and breeding behavior characteristics, collection and evaluation of semen, tests to determine freedom from infectious or contagious disease, and production of foals free of genetic defects. This information should allow the examiner to anticipate the impact of the stallion on the reproductive efficiency of a group of mares. The br...
Legacki EL, Corbin CJ, Ball BA, Scoggin KE, Stanley SD, Conley AJ.Steroidogenic enzymes in placentas shape steroid hormone profiles in the maternal circulation of each mammalian species. These include 3β-hydroxysteroid dehydrogenase/Δ5-4 isomerase (3βHSD) and 17α-hydroxylase/17,20-lyase cytochrome P450 (P450c17) crucial for progesterone and androgen synthesis, respectively, as well as aromatase cytochrome P450 (P450arom) that converts Δ4-androgens to estrogens. 5α-reductase is another important enzyme in equine placentas because 5α-dihydroprogesterone (DHP) sustains pregnancy in the absence of progesterone in the second half of equine pregnancy. DHP a...
Aoki T, Chiba A, Itoh M, Nambo Y, Yamagishi N, Shibano KI, Cheong SH.The purpose of this study was to elucidate the colostral and foal serum immunoglobulin G (IgG) concentration values in heavy draft horses in Japan and to examine the effects of peripartum mare condition on colostral immunity. Colostrum was obtained 1 hr after foaling (pre-suckling; n=178). Blood was collected from the jugular vein of the foals (n=147) at 24 to 48 hr after birth. The foaling statuses of 73 mares were recorded. The average colostral IgG concentration was 10,540 ± 3,190 mg/dl (median=10,928; range 1,434-17,514 mg/dl). The average serum IgG concentration obtained from neonatal fo...
Clark KE, Squires EL, McKinnon AO, Seidel GE.Equine embryos were recovered nonsurgically 6.5 d after ovulation (Exp. 1) and those greater than 200 microns were stored in one of three media: 1) Ham's F10 + 10% fetal calf serum (FCS) under 5% CO2, 5% O2 and 90% N2 at 24 C (Ham's F10); 2) Minimal Essential Medium with Hank's balanced salts + 10% FCS in air (MEM) at 24 C or 3) MEM at 5 C n = 10/treatment). Embryos less than or equal to 200 micron (n = 10) were bisected microsurgically; one-half of each embryo was stored in Ham's F10 and the other half in either Dulbecco's phosphate-buffered saline + 10% FCS in air at 24 C (DPBS), or MEM in a...
Ducheyne KD, Rizzo M, Cuervo-Arango J, Claes A, Daels PF, Stout TAE, de Ruijter-Villani M.Invitro embryo production is an increasingly popular means of breeding horses. However, success is limited by a high incidence of early embryo loss. Although there are various possible causes of pregnancy failure, chromosomal abnormalities, including aneuploidy, are important potential contributors. This study evaluated the frequency of micronucleus formation as a proxy for aneuploidy in invitro-produced (IVP) and invivo-derived horse blastocysts. Associations between IVP embryo morphology, frequency of nuclear abnormalities and the likelihood of pregnancy were investigated. IVP blastocysts ex...
Tanaka Y, Taniyama H, Tsunoda N, Shinbo H, Nagamine N, Nambo Y, Nagata S, Watanabe G, Herath CB, Groome NP, Taya K.Immunolocalization of the inhibin (a) and inhibin/activin (beta3A and betaB) subunit proteins in equine fetal testes was investigated to determine the ability of the fetal testis to produce inhibins at 120, 150, 200, and 250 days of gestation. In addition, concentrations of immunoreactive (ir)-inhibin, inhibin pro-aC, and inhibin A in both the maternal and fetal circulation were measured. It was found that plasma concentrations of ir-inhibin, inhibin pro-alphaC, and inhibin A were much higher (P < .05) in the fetal than in the maternal circulation at any stage of gestation examined. Similar...
Rizzo A, Sciorsci RL.Homocysteine (Hcy) is a thiol-containing essential amino acid, important for the growth of cells and tissues. Several hypotheses exist regarding Hcy toxicity in humans; Hcy is involved in protein structural modifications, oxidative stress, and neurotoxicity induction and is therefore associated with several pathological conditions in humans. In veterinary science, knowledge regarding Hcy has increased recently due to several studies; however, many aspects remain undiscovered. Many details remain unknown regarding the effect of Hcy levels on pregnancy and the optimal management of pathological ...
Nagel C, Erber R, Ille N, von Lewinski M, Aurich J, Möstl E, Aurich C.External and internal stressors prolong parturition in different species. At parturition, sympathoadrenal activation should be avoided because an increased sympathetic tone may cause uterine atonia via β2-receptors. We hypothesized that at physiological parturition, horses are under parasympathetic dominance, and stress-response mechanisms are not activated during delivery of the foal. To evaluate stress responses, heart rate, heart rate variability, catecholamines, and cortisol were analyzed in mares (n = 17) throughout foaling. Heart rate decreased from 2 hours before (51 ± 1 beats/minute)...
Stewart F, Kennedy MW, Suire S.Horses, donkeys, and therefore, probably all equids, secrete a nonglycosylated, progesterone-dependent, 19-kDa protein (P19) into the uterine lumen during early pregnancy, and significant quantities of it are taken up by the developing conceptus. Sequence analysis and structural modelling have identified P19 as a lipocalin with greatest similarity to the murine major urinary protein lipocalins. However, lack of strong identity with any particular group of lipocalins and several unusual structural features, including a unique amino acid triplet within one of the invariant domains and an unusual...
Erol E, Jackson CB, Steinman M, Meares K, Donahoe J, Kelly N, Locke S, Smith JL, Carter CN.A comprehensive evaluation of the real-time PCR assay for leptospirosis in comparison with other diagnostic assays on a large-scale basis is fundamental in validating the assay and determining the causes of equine abortions. Objective: To compare and evaluate the diagnostic value of real-time PCR assay for leptospirosis with traditional methods in equine leptospiral abortions. Methods: Cross-sectional observational study. Methods: A Leptospira spp. fluorescent antibody test (FAT), microscopic agglutination test (MAT) and real-time PCR (targeting the LipL32 gene) were compared and evaluated in ...
Gravance CG, Champion Z, Liu IK, Casey PJ.The evaluation of seminal characteristics is important in the clinical detection of stallion subfertility. Conventional semen evaluation includes subjective determination of sperm concentration, motility, and gross morphology. Due to the subjectivity and variability of the manual morphology assessment, computer automated sperm morphology analyses has been developed. Computer automated sperm morphology analysis was applied in the current study to determine if the morphometric measurements of sperm heads from collected and dismount samples of the same ejaculate were similar. If the post-ejaculat...
Wilsher S, Allen WR.An opportunity to monitor equine chorionic gonadotrophin (eCG) production during 61 pregnancies in 25 Thoroughbred mares mated to the same Thoroughbred stallion was utilised in order to further knowledge regarding factors involved in the production of this hormone. Objective: To examine the effects of maternal body condition, exercise and parity on eCG production. Methods: In the first experiment, maiden mares were fed either a moderate (n = 9) or an excessive (n = 10) food intake throughout gestation. In the second experiment, 5 mares were exercised daily during pregnancy and eCG production r...
Swegen A, Smith ND, Gibb Z, Curry BJ, Aitken RJ.Serine proteases are emerging as important players in the spermatozoon's acquisition of functional competence. This study aimed to characterize the serine protease testisin (PRSS21) in stallion spermatozoa, examining its surface expression, possible origins in the testis and epididymis, and changes in response to capacitation and acrosome reaction, as well as its capacity to form high molecular weight complexes and interact with other proteins. The role of serine proteases in spontaneous capacitation and acrosome reaction of stallion spermatozoa was established using the serine protease inhibi...
Stout TAE.The first reports of in vitro embryo production (IVEP) by conventional in vitro fertilization and intracytoplasmic sperm injection in horses date respectively from approximately 30 and 25 years ago. However, IVEP has only become established in clinical practice during the last decade. The initial slow uptake of IVEP was largely because the likelihood of success was too low to make it an economically viable means of breeding horses. During the last decade, the balance has shifted, primarily because of significant improvements in the efficiency of recovering immature oocytes from live donor m...
Rota A, Furzi C, Panzani D, Camillo F.This study on extended, cooled stallion spermatozoa aimed to compare the ability of three extenders to maintain sperm motility during 24 h of preservation, and to describe pregnancy and foaling rates after artificial insemination (AI) of stallion spermatozoa stored and transported in the extender chosen from the in vitro study. After 6 and 24 h of preservation, motility, both subjective and evaluated by the motility analyzer (total, progressive and rapid), was lower in non-fat, dried skim milk-glucose than in both other extenders: dried skim milk-glucose added to 2% centrifuged egg yolk, and u...
Galvão A, Tramontano A, Rebordão MR, Amaral A, Bravo PP, Szóstek A, Skarzynski D, Mollo A, Ferreira-Dias G.Metabolic hormones have been associated with reproductive function modulation. Thus, the aim of this study was: (i) to characterize the immunolocalization, mRNA and protein levels of leptin (LEP), Ghrelin (GHR) and respective receptors LEPR and Ghr-R1A, throughout luteal phase; and (ii) to evaluate the role of LEP and GHR on progesterone (P4), prostaglandin (PG) E2 and PGF2α , nitric oxide (nitrite), tumor necrosis factor-α (TNF); macrophage migration inhibitory factor (MIF) secretion, and on angiogenic activity (BAEC proliferation), in equine corpus luteum (CL) from early and mid-luteal sta...
Bollwein H, Weber F, Woschée I, Stolla R.Transrectal color Doppler sonography was used to investigate uterine and umbilical blood flow during pregnancy (duration, 46-48 weeks) in four mares. The resistance index (RI) and blood flow volume (VOL) of the uterine arteries ipsilateral and contralateral to the conceptus, and the presence of an early diastolic notch in the Doppler wave, were evaluated every 4 week throughout pregnancy. Fetal blood flow was calculated semiquantitatively every 2 week (from 20 to 40 weeks), using the RI of the umbilical arteries. During the entire period of investigation, there were no significant individual v...
Brück I, Anderson GA, Hyland JH.The records of 1630 mare years from 6 Thoroughbred stud farms in south eastern Australia were analysed for the years 1981 to 1986. Overall pregnancy and foaling rates were 83.9% and 69.3%, respectively. When calculated per served oestrous cycle, pregnancy and foaling rates were 54.7% and 43.1%, respectively. Pregnancy and foaling rates were higher (P < 0.001) for mares 3 to 10 years of age than for older mares. There was no difference in the pregnancy rates of maiden, barren and foaling mares. The foaling rate was significantly higher (P < 0.001) in mares that became pregnant during the ...
Bosh KA, Powell D, Neibergs JS, Shelton B, Zent W.There have been no studies reporting the impact of reproductive efficiency and mare financial value on economic returns. Objective: To explore the economic consequences of differences in reproductive efficiency over time in the Thoroughbred mare. Methods: Complete production records for 1176 mares were obtained. Production history and drift in foaling date were calculated. Multiple logistic regression was used to identify factors influencing the probability of producing a registered foal in 2005. The 'net present value' and 'internal rate of return' were calculated for economic scenarios invol...
Beyer T, Rink BE, Scarlet D, Walter I, Kunert S, Aurich C.In the horse, it is still unclear if and to what extent low progestin concentration contributes to early conceptus loss. In the present study, we have investigated if reduced or elevated progestin concentration in the early luteal phase influences endometrial function and conceptus development. We hypothesized that reduced progestin concentration via delayed downregulation of endometrial progesterone receptors (PR) influences endometrial function in healthy fertile mares while progestin substitution does not. Genitally healthy estrous mares (n = 8; age 4-14 years) were inseminated and trea...
Lee G, Jung H, Yoon M.The molecular markers for specific germ cell stages can be utilized for identifying, monitoring, and separating a particular stage of germ cells. The RNA-binding protein Lin28 is expressed in gonocytes of human fetal testes. The Lin28 expression is restricted to a very small population of spermatogonial cells in human, mice, and monkey. The main objective of this study was to investigate the expression pattern of Lin28 in stallion testes at different reproductive stages. Based on the presence or absence of full spermatogenesis and lumina in seminiferous tubules, the testicular samples were cat...
Twenter H, Klohonatz K, Davis K, Bass L, Coleman SJ, Bouma GJ, Bruemmer JE.All epididymal regions are lined with multiple epithelial cell types, each with different functions to provide the luminal environment for spermatozoal maturation. Epithelial cells also create apical blebs, which are released from the apical surface via apocrine secretion and disintegrate in the lumen, thereby releasing epididymosomes. Epididymosomes transport proteins to spermatozoa and contain microRNAs. We hypothesized that epididymosomes also transfer miRNA from epididymal epithelium to spermatozoa. Quantitative real-time polymerase chain reaction was used to determine miRNA profiles of ep...
Samper JC, Hellander JC, Crabo BG.Studies were designed to investigate whether sperm motility determined with a Hamilton-Thorn HTM-2000 motility analyzer (HTM), or the percentage of spermatozoa that passed through glass wool (GW), Sephadex (S), or glass wool/Sephadex (GWS) filters could be used to predict the fertilizing potential of fresh or frozen semen. In the fresh semen study, 10 randomly selected ejaculates from 4 stallions exclusively used for A.I. breeding were assayed during the season. The 521 mares used were inseminated with 500 x 10(6) motile spermatozoa after gynaecological examination every 2 days. In the frozen ...
Gastal EL, Gastal MO, Ginther OJ.A duplex grey-scale and colour-Doppler ultrasound instrument was used to study the changes in the wall of the preovulatory follicle in mares. When the follicle reached > or =35 mm (hour 0), mares were randomized into control (n = 16) and human chorionic gonadotropin (hCG)-treated (n = 16) groups. The hCG treatment was given at hour 0. Scanning was done every 12 h until hour 36, every hour between hours 36 and 48, and every 12 h thereafter until ovulation. Blood was sampled every 12 h for oestradiol assay. During the period 0-24 h post-treatment, oestradiol concentrations decreased in the hC...
Nagel C, Melchert M, Aurich J, Aurich C.Cortisol is involved in the initiation of parturition and we hypothesized that increased maternal cortisol release advances the onset of foaling. Transport is a stressor for horses and induces an increase in cortisol release. To determine stress effects on the time of foaling, late-pregnant mares were transported by road for 3 hours (n = 12) or remained in their stable as controls (n = 4). Starting on day 325 of gestation, saliva and blood samples were taken for cortisol and progestin analysis, respectively. Fetomaternal electrocardiograms were recorded repeatedly. Mares were checked for im...
Herrera-Luna CV, Scarlet D, Walter I, Aurich C.The aim of the present study was to characterise receptors for LH and FSH (LHR and FSHR, respectively) and aromatase in epididymal and testicular tissue from stallions of different ages (prepubertal, young, mature and old). Gene and protein expression were assessed by real-time quantitative polymerase chain reaction (real-time qPCR), immunohistochemistry and multiple immunofluorescence labelling. There were no differences in LHR mRNA expression in epididymal and testicular parenchyma in stallions of different age. In contrast, expression of FSHR and CYP19A1 in caput, corpus and cauda epididymi...
Hinrichs K, Spensley MS, McDonough PL.To investigate a model for equine endometritis, 12 mares with normal reproductive tracts were divided into 2 groups. All mares received progesterone in oil, 250 mg im, daily. At 5 days after initiation of progesterone administration, the uteri were inoculated with 10(6) colony forming units of Pseudomonas aeruginosa. The day of inoculation was designated Day 0. On Day 6, endometrial swab samples yielded P. aeruginosa in 5 mares; samples from the other 7 mares yielded heavy growth of Escherichia coli, Streptococcus zooepidemicus, Klebsiella pneumoniae, Enterobacter spp., Citrobacter diversus, S...
Juhász J, Nagy P, Kulcsár M, Szigeti G, Reiczigel J, Huszenicza G.The effect of 10-day zearalenone administration starting 10 days after ovulation was studied in 6 cycling trotter mares in the summer period. After an entire oestrous cycle (Cycle 1), mares were given 7 mg purified zearalenone per os daily (1 mg/ml in ethyl alcohol) beginning on Day 10 of Cycle 2. Toxin exposure was continued until the subsequent ovulation. Luteal function and follicular activity were monitored daily by rectal palpation, ultrasonography and blood sampling for progesterone. During toxin exposure, all animals were in good physical condition. The toxin had no effect on the length...
