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.
Heinrich B.This research article corrects a common misconception about the energy metabolism in horses during short sprinting and long-distance running events, emphasizing that short sprints are primarily powered by anaerobic activity, […]
Houpt KA.Some of the techniques that may be used to study social, reproductive, and ingestive behavior in horses are described in this paper. One of the aspects of equine social behavior is the dominance hierarchy or patterns of agonistic behavior. Paired or group feeding from a single food source may be used to determine dominance hierarchies quickly. Focal animal studies of undisturbed groups of horses may also be used; this method takes longer, but may reveal affiliative as well as agonistic relationships among the horses. Reproductive behavior includes flehmen, the functional significance of which ...
Weber JA, Freeman DA, Vanderwall DK, Woods GL.This study was conducted to identify embryonic products whose secretion was temporally associated with the oviductal transport period of the mare. Chemicals secreted by oviductal-transport-stage equine embryos were identified by incubating Day 6 or Day 7 early uterine embryos with 35S-methionine/cysteine, 3H-progesterone, or 3H-arachidonic acid for 24 h, and subsequently identifying radioactively labeled proteins (SDS-PAGE; n = 3 embryos), steroids (HPLC; n = 3 embryos), or prostaglandins (HPLC; n = 3 embryos) in the culture medium. Early uterine embryos secreted 116.1 +/- 45.5 pg of prostagla...
Liu DY, Lopata A, Pantke P, Baker HW.The present study demonstrates that horse and marmoset monkey sperm can bind to the human zona of salt-stored oocytes that failed to fertilize in vitro. Marmoset monkey sperm are also able to penetrate the salt-stored human zona. In contrast, human sperm do not bind to the zona of either horse or marmoset monkey oocytes. These results suggest that human sperm binding to the zona pellucida is more strictly species-specific than it is for horse and marmoset monkey sperm. In contrast, horse and marmoset monkey sperm contain receptors recognized by the human zona.
Whalley M, Robertson G, Bell C, Love D, Elphinstone M, Wiley L, Craven D.A homologue of the herpes simplex virus (HSV) glycoprotein D gene has been identified in the genome of equine herpesvirus-1 (EHV-1, equine abortion virus). An open reading frame in the middle of the short unique (US) region is capable of encoding a polypeptide of 402 amino acids that has 26% and 20% of its residues matching pseudorabies virus (PRV) gp50 and HSV-1 gD, respectively. Despite this low level of similarity, the positional identity of six cysteine residues and certain motifs, and the location of the EHV-1 gene, clearly define the EHV-1 polypeptide as one of a family of "gD-like" prot...
Martinuk SD, Manning AW, Black WD, Murphy BD.The sialylation of eCG was examined to determine its influence on the in vivo metabolism and biological activity of the molecule. Sialic acid was decrementally removed from eCG by incubation with agarose-linked neuraminidase for varying time periods. Pharmacokinetic parameters for the disappearance of 4,000 IU (267 micrograms) of three desialylated eCG preparations (20%, 53%, and 80% sialic acid removed) and control eCG were determined in sheep. The clearance rate of eCG increased (p less than 0.05) with each decrement of sialic acid. The removal of 53% sialic acid enhanced the distribution of...
Weber JA, Freeman DA, Vanderwall DK, Woods GL.The hypothesis that treatment of pregnant mares with prostaglandin E2 (PGE2) hastens the oviductal transport of equine embryos was tested by treating bred mares with PGE2 on Day 3 after ovulation and subsequently measuring the rate of hastened oviductal transport (estimated by the uterine embryo recovery rate on Day 4 after ovulation). In a preliminary, noncontrolled experiment, oviductal transport was apparently not hastened after intramuscular, intrauterine, or intraperitoneal PGE2 administration to bred mares (0/6, 0/3, and 0/3 mares, respectively). Oviductal transport appeared to be hasten...
McDonnell SM, Pozor MA, Beech J, Sweeney RW.A 9-year-old atactic breeding stallion was trained to ejaculate, with only manual stimulation, while standing on the ground. Ejaculates obtained yielded fertile semen with morphologic and motility characteristics within the range for normal stallions. This method extended the breeding life of a stallion unable to mount a live or dummy mare or to ejaculate into an artificial vagina while standing on the ground.
Kot K, Tischner M.The aim of the experiment was to determine the effect of a year-to-year prolonged daylength on the patterns of equine reproductive activity and results of embryo recovery. Experiments using Konik Polski mares were conducted over four reproduction seasons. Five mares were exposed to a regimen of artificially prolonged daylength (APD) and another five mares in a control group were kept under conditions of natural daylight. Both the control and experimental groups were examined for appearance of estrus, ovulation and also for the state of their coats. A single stallion was used for breeding all o...
Lowis TC, Hyland JH.This project surveys the reproductive performance of 154 foaling Thoroughbred mares on a commercial stud in southern Victoria. Of these, 96 were served on foal heat (FHS) and 58 were served at a subsequent prostaglandin-induced oestrus (PGS). The PGS group of mares performed more favourably in all aspects except the foaling-to-conception interval where there was a 9.4 day advantage to the FHS group. The first service conception rate in the FHS group was 47.9% compared with 55.2% in PGS mares. Second heat period conception rates were 46% vs 57.7% for FHS and PGS mares, respectively. Overall con...
Heap RB, Hamon MH, Allen WR.Aromatase distribution in membranes of preimplantation horse and donkey conceptuses was compared by measuring the incorporation of [3H]androstenedione into oestrone and oestradiol-17 beta. In the donkey conceptus, aromatase activity was similar in all the tissues examined (yolk sac, chorionic girdle and allantochorion), whereas in the horse it was generally lower and showed the relationship chorionic girdle greater than yolk sac greater than allantochorion. A higher proportion of labelled precursor was incorporated into oestradiol-17 beta by extra-embryonic tissues of the donkey compared with ...
Watson ED, Sertich PL, Zanecosky HG.Ovulation has been likened to an inflammatory process. Inflammatory cells accumulate in the ovulating follicle, presumably because of chemotactic factors. Chemotactic activity was measured in fluid aspirated from follicles of estrous mares 0, 12, 24, and 36 hours after ultrasonographic detection of a 35-mm follicle and IV treatment with 2,500 IU of human chorionic gonadotropin. Chemotaxis was assessed by measuring directional migration of equine neutrophils under agarose. Follicular fluid acted as a chemoattractant for neutrophils, but there was no significant difference in chemotactic activit...
Johnson L, Varner DD, Tatum ME, Scrutchfield WL.To evaluate the effect of age and season on Sertoli cell number per paired testes, ratio of germ cells per Sertoli cell, and daily sperm production, testes were obtained from 184 adult (4-20 yr) stallions at slaughter throughout one year. Numbers of Sertoli cells or germ cells were derived from nuclear volume density, volume of individual nuclei, and parenchymal volume. Germ cell to Sertoli cell ratios were calculated from cell numbers. Regression analysis was used to detect age-related differences in the breeding season (May-Jul) or throughout the year. A two-way analysis of variance was used...
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...
Büchi S, Waelchli RO, Corboz L, Gygax AP, Wälti RJ.In the mare, natural breeding is associated with bacterial contamination of the reproductive tract. The purpose of this study was to examine postcoital bacterial contamination and the resulting inflammatory response of the uterus. Uterine swabs for bacteriological and cytological examination were obtained from 80 mares. Each mare was sampled once between 4 and 69 hours postbreeding. In mares which did not conceive, sampling was repeated at the following estrus. The findings were compared with those obtained prior to breeding and correlated with the breeding outcome. Bacteria were cultured from...
Padilla AW, Foote RH.Slow-cooled stallion spermatozoa, with and without seminal plasma removed by centrifugation, were diluted in Kenney's extender (KE) containing nonfat dry skim milk with glucose and antibiotics or in KE supplemented by adding a modified high-potassium Tyrode's medium (KMT). Four ejaculates from each of four stallions were collected and divided factorially across these four treatments. Percentage of motile sperm, path velocity, and linearity immediately after treatment (0 h) and after storage at 4 degrees C for 24, 48, and 72 h were evaluated objectively by use of a HTM-2030 sperm motility analy...
Hopkins B, O'Connell FM, Hopkins J.DNA fingerprinting techniques were used to try to resolve the parentage of an Exmoor pony foal. Three young Exmoor ponies, one female and two males, shared a paddock and the female subsequently became pregnant. The two possible sires were three-quarter siblings and were also half-siblings to the dam. Southern hybridisation of Exmoor pony DNA with human mini-satellite probes resolved the disputed parentage in spite of the fact that there was a 70 per cent band share between the individuals involved. Colt M6 was 2.06 times more likely to be the father than an uncle, and Colt M3 was 477 times mor...
Stewart DR, Nevins B, Hadas E, Vandlen R.Relaxin, a polypeptide hormone normally associated with pregnancy, has been purified from many species, and the sequence determined for a growing number. Equine relaxin has been previously purified by acetone extraction, gel filtration, and ion exchange chromatographies. In an attempt to develop a more rapid and efficient method for relaxin purification, the use of affinity chromatography coupled with HPLC was explored. Monoclonal antibodies were raised against highly purified equine relaxin; large quantities of antibody were obtained by ascites production and attached to a solid phase support...
Carney NJ, Squires EL, Cook VM, Seidel GE, Jasko DJ.Donor mares of mixed, light-horse breeds, maintained at Colorado State University, provided 104 embryos for immediate transfer (fresh embryos). One hundred and thirty-six additional embryos were collected on various breeding farms in the United States and were shipped to Colorado State University via commercial airlines (cooled embryos). Embryos were harvested 7 d after ovulation, graded, and either transferred into a mare immediately (<1 h) or placed in Ham's F-10 medium plus 10% fetal calf serum in an atmosphere of 5% CO2, 5% O2, 90% N2 and packaged in a passive cooling unit (Equitai...
Arrighi S, Romanello MG, Domeneghini C.Following previous studies about the ultrastructure of male genital tract in parental species, a comparative study of epididymis of one of the possible hybrids, the mule, has been undertaken. Apart from small differences, general features of epididymal epithelium in the mule are similar to those of parental species. However, extension of our studies from the donkey to the horse to the hybrid permits a deeper insight into the morphology of this tract of excurrent duct. In the meantime, it is possible to evidence some features, sometimes shared with other species if taken separately, which in th...
Monet-Kuntz C, Guillou F, Fontaine I, Combarnous Y.Using a suspension of seminiferous tubule cells, we had previously shown that equine FSH is superactive in the male rat, i.e. that it exhibits a higher biological potency than expected from its binding activity. In this work we investigated equine FSH superactivity in rat, pig and sheep, by comparing in each species the equine FSH with the homologous FSH, both for their binding activities (in a radioreceptor assay using a testicular membrane fraction) and for their in vitro biological potencies (in a plasminogen activator assay using a Sertoli cell-enriched population cultured on plastic). In ...
Schmidt AR, Williams MA, Carleton CL, Darien BJ, Derksen FJ.Serial transabdominal amniocentesis was performed on eight mares in late gestation. Ultrasonography was used to identify the two placental fluid sacs and the foetus. A biopsy guide attached to the transducer allowed visualisation of the needle path during insertion. Amniotic fluid was obtained in 85 per cent of the attempts, although as mares approached parturition substantial pools of amniotic fluid were more difficult to locate. Two mares aborted during the study probably because of complications of the procedures, whereas six mares produced normal foals at term. The abortions preclude clini...
Watson ED, Zanecosky HG.Immunosuppressive substances which interfere with lymphocyte blastogenesis are released in vitro by embryos and endometrium from mares in early pregnancy. Immunosuppression was not evident when tissues were cultured in the presence of indomethacin (a prostaglandin-synthesis inhibitor). Various prostaglandins (PGs) were added to equine lymphocytes and lymphocyte proliferation was measured after the addition of concanavalin A (Con A) or phytohaemagglutinin A (PHA). PGE2 and PGF2 alpha inhibited Con A-induced blastogenesis down to final concentrations of 1.8 x 10(-9) M and 1.3 x 10(-6) M, respect...
Pinaud MA, Roser JF, Dybdal N.In vitro responsiveness of the horse anterior pituitary (AP) gonadotropes to single and multiple GnRH challenges was examined. The pituitaries were collected from reproductively sound mares in estrus (n = 5) and diestrus (n = 5). Uniform 0.5 mm AP slices were subdivided using a 3 mm biopsy punch and then bisected for use in the perifusion chamber. Four bisected sections per chamber were perifused at 0.5 ml/min at 37 C for 560 min in Medium 199 saturated with 95% 0(2)/5% CO2. Ten minute fractions were collected after an initial 2 hr equilibration period. Four different treatment regimes of GnRH...
Salmon SA, Walker RD, Carleton CL, Shah S, Robinson BE.Gardnerella vaginalis has been isolated from women with bacterial vaginosis, from the genital tracts of asymptomatic women, and from several other infected body sites in humans. However, until recently, it has not been isolated from any other animal species. Between June 1988 and October 1989, 31 isolates identified as G. vaginalis and 70 isolates identified as G. vaginalis-like organisms have been recovered from the genital tracts of 93 mares from Michigan and Ohio. Identification was based on biochemical reactions, hemolysis on media containing blood from various animal sources, and suscepti...
Blythe LL, Craig AM, Lassen ED, Rowe KE, Appell LH.Plasma alpha-tocopherol (vitamin E) values were monitored serially in 9 foals sired by a stallion with equine degenerative myeloencephalopathy (EDM) and in 5 age-matched control foals (sired by a clinically normal stallion) raised in the same environment for the first year of life. Clinical evaluation determined that 8 of the 9 foals sired by the stallion with EDM had neurologic deficits consistent with the disease on one or more occasions during the study period, whereas control foals had normal gait. From 6 weeks to 10 months of age, plasma alpha-tocopherol values in foals with signs of EDM ...
Pazinato FM, Curcio BDR, Varela Junior AS, Corcini CD, Wendt CG, Moreira F, Schmit RA, Nogueira CEW.Placental tissues from humans, rodents, and farm animal contain leptin and its receptor. Expression of leptin has already been described in horses, although there is no description about immunolocalization of leptin and its receptor. The aim of the present study was to investigate the presence and distribution of leptin and ObR-b in the equine placenta at term by immunofluorescence staining, and the changes on plasma leptin concentrations during late gestation. The present study involved eight Criollo-type mares carrying healthy pregnancies. Blood samples were collected during the third trimes...
Ferreira JC, Ignácio FS, Rocha NS, Thompson DL, Pinto CR, Meira C.The present experiment was divided into two studies to investigate the effect of age and endometrial degeneration on uterine blood flow of mares throughout the immediate post-breeding period. In study 1, uterine blood flow was characterized in mares (n = 7 mares/group) with minimal, moderate or severe endometrial degenerative changes (GI, GII and GIII, respectively). In study 2, the effect of age was investigated using young (≤ 6 years) and old (≥ 15 years) mares (n = 7 mares/group). Uterine vascular perfusion and mesometrial pulsatility index (PI) were evaluated every hour from H0 (moment...
Bertero A, Ritrovato F, Evangelista F, Stabile V, Fortina R, Ricci A, Revelli A, Vincenti L, Nervo T.The purpose of this study was to observe -matured equine oocytes with an objective computerized technique that involves the use of a polarized light microscope (PLM) in addition to the subjective morphological evaluation obtained using a classic light microscope (LM). Equine cumulus-oocyte complexes (COCs, = 922) were subjected to different maturation times (24, 36 or 45 h), however, only 36-h matured oocytes were analyzed using CLM. The 36-h matured oocytes that reached maturity were parthenogenetically activated to evaluate the quality and meiotic competence. Average maturation perce...
Ewert M, Böröcz J, Uphaus H, Oldenhof H, Distl O, Sieme H.The aim of this study was to evaluate factors affecting pregnancy rates in the German Thoroughbred Breed with particular emphasis on optimisation of fertility rates for breeding stallions of older ages. Methods: Data from the studbooks of the German Thoroughbred Breeding Association from 1996 to 2009 analysed. This analysis included the records of 319 stallions and 6622 brood mares, resulting in 21,372 pregnancies at the end of the season. Results: Pregnancy rates were significantly affected by the age of the stallion and mare as well as the season (month in the breeding season in which coveri...
Loux S, Robles M, Chavatte-Palmer P, de Mestre A.Development and the subsequent function of the fetal membranes of the equine placenta require both complex and precise regulation of gene expression. Advancements in recent years in bioinformatic techniques have allowed more extensive analyses into gene expression than ever before. This review starts by combining publically available transcriptomic data sets obtained from a range of embryonic, placental and maternal tissues, with previous knowledge of equine placental development and physiology, to gain insights into key gene families relevant to placentation in the horse. Covering the whole o...
Holyoak GR, Little TV, Vernon M, McCollum WH, Timoney PJ.Correlation between serum testosterone concentration and morphometric findings from ultrasonography of the accessory sex glands in peripubertal colts was investigated during pubertal development. Nineteen colts of initial age ranging from 5 to 12 months were monitored over a 13-month period. Serum testosterone concentration was determined on a biweekly basis, and accessory sex gland development was ultrasonographically monitored once a month. Notwithstanding individual variation, there was significant correlation (r = 0.913; P < 0.01) between increasing serum testosterone concentration and ...
Viñoles C, Quintans G, Paiva N, Cavestany D.The ovarian responses of anoestrus beef cows to a combined treatment with medroxy-progesterone acetate (MAP) sponges and oestradiol benzoate or equine chorionic gonadotrophin (eCG) were evaluated. Forty-five suckling Hereford cows were allocated to three equal groups. Group 1 received a MAP sponge for seven days plus an injection of 2 mg oestradiol benzoate when the sponge was inserted (day 0) and 1 mg when the sponge was withdrawn; group 2 received identical treatment until day 7, when a dose of 400 iu of eCG was administered, and group 3 were left untreated as control animals. From day 0 to ...
Pozor M, Freeman D, Troedsson M, Brown M, Morton A, Smith A, McNaughten J.Fusion anomalies of the epididymis with the testis may be clinically relevant in horses. However, anatomical variations in epididymal-testicular fusion have not been classified, and their clinical significance is unknown. Objective: To describe anatomical variations and clinical significance of epididymal-testicular fusion in stallions. Methods: Anatomical study of testes from castrations, and description of 2 clinical cases with atypical epididymal-testicular fusion. Methods: A total of 104 testes were obtained from equine castrations. Eight patterns of epididymal-testicular fusion were ident...
Joujou-Sisic K, Granérus M, Wetterling H, Wikström K, Engström W, Jeffcott L, Schofield PN, Welin A.The expression of the insulin like growth factor (IGF) II gene has been examined in the developing equine fetus. It was found that IGF II transcripts were present in abundant quantities in third trimester embryonic and extraembryonic tissues as for example the placenta. The expression of the IGF II gene was high in the fetal liver where two prominent transcripts--4.6 and 4.1--kB were produced. However, these transcripts could not be traced in the adult liver. Instead we found two different transcripts with the sizes of 4.0 and 2.9 kB in the adult liver. These findings taken together with the d...
Arroyo-Salvo C, Sanhueza F, Fuentes F, Treulén F, Arias ME, Cabrera P, Silva M, Felmer R.Conventional in vitro fertilization has not yet been implemented in the equine species. One of the main reasons has been the inability to develop a culture medium and incubation conditions supporting high levels of stallion sperm capacitation and hyperactivation in vitro. Although different culture media have been used for this purpose, human tubal fluid (HTF) medium, widely used in the manipulation of human and mice gametes, has not been reported so far in stallion sperm culture. The first part of this study aimed to compare HTF and Whitten's media on different stallion sperm quality and capa...
Gentry LR, Thompson DL, Stelzer AM.Seventeen seasonally anovulatory light horse mares were treated daily, starting January 5 (d 1), for 28 d with GnRH analog (GnRH-A; 50 ng/kg BW) and(or) thyrotropin-releasing hormone (TRH; 5 microg/kg BW) in a 2 x 2 factorial arrangement of treatments to test the hypothesis that combined treatment may stimulate follicular growth and development. Ovaries were examined via ultrasonography and jugular blood samples were collected every 3 d. Frequent blood samples were collected after treatment injections on d 1, 2, 4, 7, 11, 16, and 22; on d 29, all mares received an i.v. mixture of GnRH, TRH, su...
Hedberg Y, Dalin AM, Santesson M, Kindahl H.Strong oestrous symptoms in the mare can cause problems with racing, training and handling. Since long-acting progesterone treatment is not permitted in mares at competition (e.g. according to FEI rules), there is a need for methods to suppress unwanted cyclicity. Spontaneous dioestrous ovulations in the late luteal phase may cause a prolongation of the luteal phase in mares. Methods: In this preliminary study, in an attempt to induce ovulation during the luteal phase, human chorionic gonadotropin (hCG) (3000 IU) was injected intramuscularly in four mares (experimental group) in the luteal pha...
Carneiro FP, Alonso MA, Redoan MA, Henriques DA, Lima FM, Oliveira RM, Cogliati B, Canisso IF, Fernandes CB.Nocardioform placentitis is a pathologically unique form of placental disease first diagnosed in central Kentucky in the mid-80s. Since then, the occurrence of nocardioform placentitis in the region has varied over the years, from sporadic cases to outbreaks. The disease has been sporadically detected in other countries and has not been confirmed in South America. A 13-year-old multiparous Mangalarga delivered a healthy filly at 340d gestation. The mare passed the fetal membranes 33 minute after foaling. Gross examination of the fetal membranes identified two focal lesions on the chorionic sur...
Mawhinney I, Davis N, Carson T, Torrens N, Wales A.The study examined and compared the sensitivity of culture and a quantitative PCR assay for screening equine semen for the presence of Taylorella equigenitalis (CEMO). Chilled semen samples, both raw and treated with extender, from two stallions were spiked with the organism at seven or 23 days postejaculation and prepared in serial dilutions. Culture of the 7-day raw semen readily detected CEMO at all dilutions, but extended semen yielded counts that were two log cycles lower at equivalent dilutions, with the organism being nearly undetectable at the maximal dilutions. By contrast, PCR sensit...
Vieira GS, Paludo GR, Ramos AF, Pivato I, de Oliveira RA.For a long time, Pantaneiro and Campeiro breeds were raised only within their places of origin. Consequently, there are few of these horses; therefore, establishing reproductive and clinical standards for these animals is necessary to implant new biotechnologies for reproduction to preserve their genetics. This study aimed to perform a descriptive evaluation of fetal age determination by fetus ocular orbit measurement in mares of the Campeiro and Pantaneiro breeds. We also evaluated sequential changes in hematology and biochemistry for foals from birth to six months of life by counting red blo...
Álvarez C, González N, Luño V, Martínez F, Gil L.The aim of this study was to test and compare two new components in extenders for freezing donkey semen: mare colostrum and jenny colostrum. Colostrum was obtained from four mares and four jennies right after the foal's birth. Ejaculates were collected from five fertile donkeys. Sperm samples were pooled, diluted and cryopreserved in three different experimental extender groups: lactose supplemented with egg yolk extender (20%) as the control group, lactose supplemented with jenny colostrum extender (20%), and lactose supplemented with mare colostrum extender (20%). After thawing, we evaluated...
Waelchli RO, Jaworski T, Ruddock WD, Betteridge KJ.Equine blastocyst fluid has a lower [Na+], a higher [K+] and a lower osmolality than does normal blood serum. Based on the assumptions that the sodium pump is primarily responsible for fluid accumulation and that ions transported actively into the blastocyst increase blastocyst osmolality above that of the external medium, we hypothesized that the [Na+] and the osmolality of mare uterine fluid are lower than those of blastocyst fluid. Microdialysis and ion chromatography were used to estimate [Na+] and [K+] of uterine fluid. Mares (n=10) were used for in vivo measurements at different stages o...
Wilcox AL, Calise DV, Chapman SE, Edwards JF, Storts RW.Hypoxic/ischemic encephalopathy in a cloned American Quarter horse foal was initially associated with placental insufficiency and exacerbated by protracted hypotension during anesthesia for a surgical procedure. The foal, born at the Texas A&M Veterinary Medical Center, was diagnosed at birth with neonatal maladjustment syndrome that was accompanied by dysmaturity, muscle contracture of the front limbs, and a blood clot within the lumen of the urinary bladder. Seizures that developed after anesthesia were attributed to hypoxia/ischemia during anesthesia and culminated in death. Macroscopically...
Nie GJ, Johnson KE, Wenzel JG.Mares were inseminated deep in the uterine horn with 25 million sperm selected by glass wool/Sephadex (GWS) filtration, Percoll separation (PS) or absolute number (AN). Deep-horn insemination using a low-volume, smooth tipped, flexible pipette/catheter delivery system allowed more efficient use of stallion sperm and reduced post-breeding uterine reaction in mares. Mares were pregnant in 15/30, 13/30 and 10/30 cycles for GWS, PS and AN selection methods, respectively. Sperm selection method did not effect pregnancy outcome (P=0.422). However, sperm selected for deep-horn insemination by filtrat...
Aurich C, Aurich JE, Parvizi N.In equine species, luteinising hormone (LH) and prolactin (PRL) release are reduced throughout pregnancy but increase at foaling. The present experiments were designed to study a possible opioidergic regulation of LH and PRL release in pregnant Shetland mares (n=6). At various stages of pregnancy (days 26.4+/-0.6, 75.4+/-5.4, 171.8+/-2.4, 226.2+/-4.8, 282.7+/-3.4 and 319.8+/-2.1), mares were injected with the opioid antagonist naloxone (0.5 mg/kg body weight) and saline. The two treatments were always separated by 2 days, and mares served as their own controls. Two hours after being given nalo...
Zavy MT, Vernon MW, Asquith RL, Bazer FW, Sharp DC.Two experiments were conducted to assess the effect of exogenous hormone treatment on uterine luminal prostaglandin F (PGF). In the first experiment ovariectomized pony mares received either corn oil (21 days, n = 3), estradiol valerate (21 days, n = 3), progesterone (21 days, n = 3) or estradiol valerate (7 days) followed by progesterone (14 days, n = 4). Progesterone treated mares had higher (P less than .01) uterine luminal PGF compared with all other groups, and no differences were detected between other treatment comparisons. In Experiment II, uterine fluid was collected from 4 ovariectom...
Ginther OJ, Gastal EL, Rodrigues BL, Gastal MO, Beg MA.Relationships between double ovulations and plasma hormone concentrations were compared between 18 single ovulating and 6 double ovulating mares. The study began when the first follicle reached >or=30 mm, and ultrasound scanning and blood sampling were done every 12h to Day 3 (ovulation=Day 0). Data were analyzed for 2.5 d after the largest follicle was >or=30 mm and after Day -2.5 to encompass the mean 5-d interval between a >or=30 mm follicle and Day 0. During the 2.5 d after >or=30 mm, the increasing diameter of the largest follicle was less pronounced and plasma FSH concentrati...
Maitan PP, Bromfield EG, Hoogendijk R, Leung MR, Zeev-Ben-Mordehai T, van de Lest CH, Jansen JWA, Leemans B, Guimarães JD, Stout TAE, Gadella BM....Classical in vitro fertilization (IVF) is still poorly successful in horses. This lack of success is thought to be due primarily to inadequate capacitation of stallion spermatozoa under in vitro conditions. In species in which IVF is successful, bicarbonate, calcium, and albumin are considered the key components that enable a gradual reorganization of the sperm plasma membrane that allows the spermatozoa to undergo an acrosome reaction and fertilize the oocyte. The aim of this work was to comprehensively examine contributors to stallion sperm capacitation by investigating bicarbonate-induced m...
Smith KC, Tearle JP, Boyle MS, Gower SM, Mumford JA.Equid herpesvirus-1 (EHV-1; Ab4 isolate) was inoculated unilaterally into the cavum vaginale of four pony colts under general anaesthesia. The animals were monitored daily for evidence of scrotal or testicular swelling and euthanased electively on days 3, 4, 6 and 12 after infection. Detailed pathological examination of the male genital tract was carried out. In animals examined at days 3 and 4 after infection, replication of EHV-1 was detected bilaterally in mesothelial and endothelial cells of the parietal and visceral vaginal tunics. The mesothelial infection had resolved by day 12 after in...
Robles M, Peugnet PM, Valentino SA, Dubois C, Dahirel M, Aubrière MC, Reigner F, Serteyn D, Wimel L, Couturier-Tarrade A, Chavatte-Palmer P.Following embryo transfer (ET), the size and breed of the recipient mare can affect fetal development and subsequent post natal growth rate and insulin sensitivity in foals. Objective: To investigate placental adaptation in pregnancies where increased or restricted fetal growth was induced through ET between Pony, Saddlebred and Draught horses. Methods: In vivo experiment. Methods: Control Pony (P, n = 21) and Saddlebred (S, n = 28) pregnancies were obtained by artificial insemination. Increased pregnancies were obtained by transferring Pony (P-D, n = 6) and Saddlebred (S-D, n = 8) emb...
Ferreira-Silva JC, Basto SRL, Moura MT, Rocha JM, Freitas Neto LM, Santos Filho JP, Silva Filho ML, Oliveira MAL.The work described here aimed to verify the efficiency of different extenders for cryopreservation of equine semen using sperm motility and acrosin activity as spermatic parameters. The semen was fractioned into two equal parts and resuspended in an 11% lactose solution in a 1:1 proportion, where it remained for 20 minutes at room temperature. The semen was centrifuged at 600 g for 10 minutes, and after the second centrifugation, each pellet received the freezing extender (Merck or Zorlesco) and was loaded into 4 mL straws. Each straw was placed in liquid nitrogen vapor steam for 15 minutes ...
Waelchli RO, Känzig M, Gygax A, Corboz L, Rüsch P.A total of 368 uterine swabs were taken from mares in heat (n = 202) and from mares that were not in heat (n = 166). From 72 of the mares, two swabs were taken; one during either seasonal anoestrus or dioestrus, and one during oestrus. Swabs were taken during anoestrus/dioestrus in 94 other mares and during oestrus in the remaining 130 mares. Bacteriological cultures were done aerobically and classified as negative, insignificant or significant. There was a trend for more positive cytological specimens during oestrus than during anoestrus/dioestrus. The proportions of significant cultures were...
Rua MA, Quirino CR, Bartholazzi Junior A, Santoro PN, Bastos R, Ribeiro Mda S, Matos LF, Vega WH.The aim of this study was to evaluate the breeding behavior of Brazilian Pony stallions during semen collection to examine the effect of age category (AC) and month of evaluation on the characteristics of breeding behavior. Nine stallions were evaluated during the breeding and non-breeding season, 5-8 (AC1) and 9-13 years (AC2) of age. The variables evaluated were reaction time (RT), mount time one (MT1) and two (MT2), mount and ejaculation time (MEjT), mounting without erection (MWEr), mounting without ejaculation (MWEj), flehmen, kicks, bites, smells, vocalizations and serum testosterone con...
Scott MA, Liu IK, Overstreet JW, Enders AC.Uterotubal junction tissues (n=12) recovered from young nulliparous mares 4 h after insemination were examined for spermatozoa in situ using scanning electron microscopy. Mares were inseminated before ovulation with semen containing 66-85% morphologically abnormal spermatozoa and approximately 1 x 10(9) progressively motile spermatozoa. Spermatozoa were found in all the tissues and displayed a variety of relationships to the epithelium, depending on regional location, spatial constraints and epithelial surface characteristics. Spermatozoa were most abundant in the epithelial folds on the uteri...
Ginther OJ, Gastal EL, Gastal MO, Duarte LF, Beg MA.The effect of the ovarian follicles on plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) before versus after the expected emergence of the ovulatory follicular wave was studied on Days 0 to 18 (Day 0=ovulation) in four groups of mares (n=6/group). In addition to a control group, all follicles >/=6mm in diameter were ablated on Days 0.5, 6.5, or 12.5 in a herd of mares with reported emergence at 6mm of the future ovulatory follicle on mean Day 10.5. Concentrations of FSH were not different between the Day-0.5 or Day-6.5 ablation groups and the correspon...
