Pregnancy in horses, or equine gestation, is a physiological process that involves the development of a foal within the mare over approximately 11 months. This period is characterized by distinct stages, including fertilization, embryonic development, and fetal growth. Throughout gestation, mares undergo various physiological and hormonal changes to support the developing fetus. Monitoring pregnancy in horses involves assessing fetal health and mare well-being through veterinary examinations and diagnostic tools such as ultrasound. This page compiles peer-reviewed research studies and scholarly articles that explore the physiological processes, management practices, and health considerations associated with equine pregnancy.
Nagel C, Melchert M, Aurich C, Aurich J.Equine fetomaternal monitoring is based on endocrine and cardiac parameters which may differ among small, medium-size, and full-size horses. Therefore, Shetland ( = 6), Haflinger ( = 8), and Warmblood pregnancies ( = 9) were studied during late gestation and at foaling. Weight of mares, foals and placenta, plasma progestin and cortisol concentration, heart rate and heart rate variability (HRV) were determined. Foal weight always approximated 10% of mare weight but relative placenta weight was highest in full-size mares ( < 0.05). Progestin ( < 0.001) and cortisol ( < 0.05) concentrati...
Beachler TM, Scott Bailey C, Gracz HS, Morgan DR, Von Dollen KA, Ellis KE, Gadsby JE, Lyle SK.The amniotic and allantoic fluid compartments in the mare serve essential roles throughout pregnancy and parturition. Although the global metabolomic profile of amniotic fluid in women has been extensively characterized, current data for equine fetal fluids are limited. Therefore, the goal of this study was to characterize the global metabolomic profile of equine allantoic and amniotic fluid through nuclear magnetic resonance spectroscopy. Fetal fluids were collected between 270 and 295 days of gestation from 12 pregnancies through ultrasound-guided transabdominal puncture. A total of 24 samp...
Auclair-Ronzaud J, Jousset T, Dubois C, Wimel L, Jaffrézic F, Chavatte-Palmer P.Gestational length is highly variable in horses ranging from 320 to 360 days. Thus, determining parturition time is an important challenge for the horse industry. Body temperature can be used in cows and ewes as an indicator of parturition. Thus, the aim of this study is to determine if temperature can also be used as indicator of foaling. Thirty-nine mares were monitored over two foaling seasons (2018 and 2019). They were housed in 16 m stalls with access to pasture in group three times a week from 10:00 to 16:00. Night watch as well as video monitoring was ensured during foaling periods. Bo...
Herrera C.Embryo cryopreservation is normally performed with great success in species like humans and cattle. The large size of in vivo-derived equine embryos and the presence of a capsule-impermeable to cryoprotectants-have complicated the use of embryo cryopreservation in equine reproduction. A breakthrough for this technique was obtained when large equine embryos could be successfully cryopreserved after collapsing the blastocoel cavity using a micromanipulation system. High pregnancy rates have been obtained when vitrification is used in combination with embryo collapse.
Andrade Junior LRP, Segabinazzi LGTM, Oliveira SN, Dell'Aqua JA, Papa FO.A high amount of blood and not the mere presence of blood in equine semen impacts fertility. The aim of this study was to develop an approach to rescue the fertility of stallions with high hemospermia levels. Semen from 15 stallions was divided into four experimental groups: (a) Control-pure raw semen, (b) WB50-50% (v/v) whole blood added into semen, (c) E1-WB50 extended in a 1:1 (v/v) ratio with milk-based extender and (d) E2-WB50 extended in a 2:1 ratio with milk-based extender. Sperm kinetics, plasma membrane integrity (PMI), lipid peroxidation (PER) and intracellular superoxide (O ) produc...
Shilton CA, Kahler A, Davis BW, Crabtree JR, Crowhurst J, McGladdery AJ, Wathes DC, Raudsepp T, de Mestre AM.The first 8 weeks of pregnancy is a critical time, with the majority of pregnancy losses occurring during this period. Abnormal chromosome number (aneuploidy) is a common finding in human miscarriage, yet is rarely reported in domestic animals. Equine early pregnancy loss (EPL) has no diagnosis in over 80% of cases. The aim of this study was to characterise aneuploidies associated with equine EPL. Genomic DNA from clinical cases of spontaneous miscarriage (EPLs; 14-65 days of gestation) and healthy control placentae (various gestational ages) were assessed using a high density genotyping arr...
Ellerbrock RE, Canisso IF, Larsen RJ, Garrett KS, Stewart MC, Herzog KK, Kersh ME, Moshage SG, Podico G, Lima FS, Childs BA.Recent studies have shown that fluoroquinolones, specifically, enrofloxacin and its active metabolite (ciprofloxacin), cross the equine placenta without causing gross or histological lesions in the first and third trimester fetuses or resulting foal. However, it is possible that in utero exposure to fluoroquinolones may cause subtle lesions not detectable by standard means; thus, a more in-depth assessment of potential toxicity is warranted. Objective: To use quantitative magnetic resonance imaging (qMRI), biomechanical testing, and chondrocyte gene expression to evaluate the limbs of foals ex...
Wilsher S, Rigali F, Kovacsy S, Allen WT.Vitrification of embryos >300 µm in diameter requires puncture of the glycoprotein capsule, although the size of the hole compatible with embryo survival is unknown. Forty-five day-7 or -8 embryos were punctured using a 30-µm glass biopsy pipette mounted on a micromanipulator (n = 20) or manually with either an acupuncture needle (∼100-µm diameter -hole; n = 10) or a microneedle with a <1 µm tip to produce a ∼30-µm diameter hole (n = 15) before transferring to recipient mares; further 12 embryos were punctured with either the acupuncture needle or microneedle before being cultured ...
Ponthier J, de la Rebière G, Salciccia A, Deleuze S.In mares, endometrial cysts are associated with endometriosis and can cause maternal recognition failure or compromise and delay pregnancy diagnoses. Historical treatments were invasive and had adverse effects on the endometrium. Hysteroscopically guided laser therapy is easy and effective for endometrial cysts resection, with no deleterious effects for the endometrium. A 110 cm long and 1.0 cm wide endoscope is sterilely introduced in the uterus through the open cervix of an estrous mare after vulvar cleaning. The uterus is slowly infused with less than 1 L of physiologic solution and the las...
Bucca S, De Oliveira IRS, Cunanan JC, Vinardell T, Troedsson MHT.Assessment of pregnancy viability in the equine patient is currently based on gestational profiles of limited prognostic value. In recent years Doppler technology has been applied to uterine and umbilical arteries of pregnant mares to monitor fetal responsive haemodynamics, suggestive of compromise. To date, uterine artery Doppler indices failed to provide sufficient evidence of pregnancy viability and the umbilical cord of the equine fetus is inconsistently visualized past 250 days gestation. The objectives of this study were to: i) evaluate intracranial blood flow impedance by Doppler examin...
Panzani D, Fanelli D, Camillo F, Rota A.In industrialized countries, the donkey population had a dramatic decrease during the last century and this has brought almost all European donkey breeds to risk. Embryo technologies have already been employed as a tool for the conservation of endangered equid species (e.g. Equus Przewalskii). Today it is possible to obtain pregnancies after the transfer of donkey embryos in synchronized recipients, even though embryo transfer is not widely used as a reproductive technique in this species. So far, very few foals are born after transfer of cryopreserved embryos. To date, no pregnancies have bee...
Camacho CA, Estradé MJ, Cazales N, Caballeros JE, Fiala-Rechsteiner SM, Neves AP, Mattos RC.This experiment aimed to verify if the proteins present in a 13 day conceptus induce changes in the equine endometrial ultra-structure, histology, and vascularization, two days after its infusion. Ten healthy cyclic mares were used. Once estrus was confirmed, mares were examined daily to detect ovulation (day 0). After ovulation, mares were examined daily until day seven by transrectal palpation and B-mode and Doppler ultrasonography. In this first cycle, intrauterine biopsies were collected at day seven after ovulation, constituting the Cyclic group (n = 10). In the second cycle, the same mar...
Becsek A, Schweizer A, Knutti B, Bollwein H.The aim of this study was to compare transrectal two-dimensional (2D) and three-dimensional (3D) ultrasound examination with regards to required time and accuracy of fetal sex determination in early pregnant mares. Methods: For this purpose 47 mares were examined transrectally once between days 58 and 115 of gestation. Initially, the fetal sex was determined by identifying the location of the genital tubercle (GT) or external genitalia using 2D-ultrasound. Subsequently, the ultrasound machine was switched to 3D-mode to obtain images for later computer-based evaluation. Results: The gestational...
Guasti PN, Souza FF, Scott C, Papa PM, Camargo LS, Schmith RA, Monteiro GA, Hartwig FP, Papa FO.During ejaculation, a large amount of seminal plasma proteins interact with the sperm membrane, leading to a series of biochemical and structural changes implicated in sperm function and gamete interaction. However, the roles of the majority of these proteins remain unknown. This study aimed to investigate the proteome and functionality of the major equine proteins of seminal plasma and the sperm membrane. Seminal plasma and enriched-membrane proteins (150 μg) were separated by two-dimensional gel electrophoresis, and the respective maps were analyzed. Protein identification was performed by...
Wilsher S, Bowker A, Silva J, Allen WRT.A total of 127 normal placentas from Arabian mares resident in the United Arab Emirates were examined. The mean linear dimensions of the placenta were, on average, 84% of those previously recorded for the placentas of the Thoroughbred. Significant differences in the size of the allantochorion between primigravid and multiparous mares were seen only in the linear dimensions of the body portion. The pregnant horn was more commonly on the right than left side of the uterus (P = .01; 74/127; 58%). Cord attachment was primarily at the base of the two placental horns (112/127; 88%), with the remain...
Dos Reis WVA, de Braga D, Júnior MV, Gheller JM, de Deco-Souza T, da Costa E Silva EV, Sampaio BFB, Macedo GG.Dispersed ovulation at the breeding (BS) and anestrus at non-breeding season (NBS) are major impediments to embryo transfer and insemination programmes. The present study aimed to evaluate a hormonal P4/E2-based synchronisation protocol in mares during both the BS and the NBS on ovarian/follicle behaviour. Mares underwent a hormone protocol to synchronise their ovulation during the BS (n = 8) and NBS (n = 10), starting (D0) with the insertion of an intravaginal device containing 1 g of P4 and 7 mg Estradiol Benzoate IM. (EB). On D9, the device was removed and injected with 0.25 mg o...
Salari F, Licitra R, Altomonte I, Martini M.We evaluated the daily intake in donkeys during maintenance, late pregnancy, and early lactation. The growth curves of the foals in the first eight weeks of life and the milk production in lactating jennies were also investigated. Donkeys were separated into two groups: seven pregnant jennies (group 1: pregnant/lactating) and seven nonpregnant, nonlactating jennies (group 2). The groups were fed two different diets each. The feeding period for group 1 covered eight weeks before parturition and eight weeks postpartum. Group 2 was managed during the same time period (16 weeks). Diet 1 consisted...
Jones CJP, Aplin JD, Allen WRT, Wilsher S.From Day 6.5-7 post-conception until its loss around Day 22, the equine embryo is enclosed in a mucinous capsule that prevents direct intercellular interaction between the trophectoderm and uterine epithelium. The embryo is, however, bathed in glycoprotein-rich secretions. In this study, lectin histochemistry was used to characterise the distribution and glycan composition of uterine glycoproteins destined for secretion, and to ascertain the local effect of an embryo on glycosylation in the endometrium. Endometrial biopsies were taken from mares in estrus, on Days 5, 8, 12 and 15 of diestrus, ...
Loux SC, Conley AJ, Scoggin KE, El-Sheikh Ali H, Dini P, Ball BA.Steroid production varies widely among species, with these differences becoming more pronounced during pregnancy. As a result, each species has its own distinct pattern of steroids, steroidogenic enzymes, receptors, and transporters to support its individual physiological requirements. Although the circulating steroid profile is well characterized during equine pregnancy, there is much yet to be explored regarding the factors that support steroidogenesis and steroid signaling. To obtain a holistic view of steroid-related transcripts, we sequenced chorioallantois (45 days, 4 months, 6 months, 1...
Suliman Y, Becker F, Tuchscherer A, Wimmers K.Horses are seasonal breeders with a natural breeding season beginning in spring and extending through midsummer. In this study, quantitative and qualitative parameters of chilled stallion semen were compared between fertile and subfertile stallions and between the breeding and the non-breeding season. Semen quality parameters compared included ejaculate volume, sperm concentration, total sperm number, sperm morphology, and computer-assisted semen analysis (CASA)-derived sperm movement characteristics obtained from two groups of warmblood stallions ( ; four fertile stallions and four subfert...
Novello G, Podico G, Segabinazzi LGTM, Lima FS, Canisso IF.The objective of this study was to compare semen parameters and embryo recovery rates of cooled stallion semen extended with INRA 96 or BotuSemen Gold. In experiment 1, 45 ejaculates from nine mature stallions were collected, assessed, and equally split between both extenders and then extended to 50 million sperm/mL. Then, the extended semen was stored in three passive cooling containers (Equitainer, Equine Express II, and BotuFlex) for 48 hours. In experiment 2, the same ejaculates extended in experiment 1 were cushion-centrifuged, the supernatant was discarded, and the pellets were resuspend...
Gáspárdy A, Renkó E, Somoskői B, Bába A, Cseh S.The objective of this study was to compare the efficiency of artificial insemination (AI) carried out with frozen and fresh, diluted and chilled semen under field conditions. One hundred and twenty-nine mares of different breeds were included in the study. Eighty-one out of the 107 mares inseminated with fresh, chilled semen got pregnant. Seven pregnant mares aborted and 74 foals were born. Out of the 22 mares inseminated with frozen semen, 17 mares got pregnant. Two mares out of the 17 pregnant mares aborted and finally 15 healthy foals were born. No difference was found between the two group...
Cuervo-Arango J, Martín-Peláez MS, Claes AN.The echogenicity of the early CL undergoes obvious changes during the first 5 days of luteal development. This phenomenon could potentially be used to estimate the age of the CL in mares which have not been checked frequently for the diagnosis of ovulation. The objective of this retrospective study was to determine the accuracy of estimating the age of the early CL (Day 0 to Day 4; Day 0 = Day of ovulation) in recipient mares examined for the first time in the breeding season to be used in a commercial embryo transfer (ET) program. The post-transfer pregnancy rate and embryo loss of 28 recip...
Piotrowska-Tomala KK, Jonczyk AW, Skarzynski DJ, Szóstek-Mioduchowska AZ.Prostaglandins (PGs) play crucial roles in the regulation of the oestrus cycle and establishment of pregnancy in animals. Luteinizing hormone (LH) and ovarian steroids are involved in regulating endometrial PG production in many species. Their effects on PG production and associated pathways in the mare myometrium and endometrium are the subjects of our interest. This study aimed to evaluate the specific effects of LH and ovarian steroids on equine myometrial and endometrial tissues on (i) PGE and PGF secretion and (ii) transcription of genes encoding specific enzymes responsible for PG synthe...
Data in briefApril 25, 2020
Volume 30 105616 doi: 10.1016/j.dib.2020.105616
Nieto-Olmedo P, Gaitskell-Phillips G, Martín-Cano FE, Ortiz-Rodríguez JM, Peña FJ, Ortega-Ferrusola C.This article provides the dataset for the use of power Doppler ultrasound to assess the equine uterus from the recent research article titled "Power Doppler can detect the presence of 7-8 days conceptuses prior to flushing in an equine embryo transfer program"(1). The vascularization of the endometrium was objectively assessed in mares by quantification of pixels in bitmap format (BMP) using computer assisted analysis of images. Fifty-two mares were examined on days 7 (26 mares) and 8 (26 mares) post-ovulation prior to performing flushing procedures for embryo recovery. Receiver operating char...
Lazzari G, Colleoni S, Crotti G, Turini P, Fiorini G, Barandalla M, Landriscina L, Dolci G, Benedetti M, Duchi R, Galli C.Assisted reproduction technologies (ART) are well developed in humans and cattle and are gaining momentum also in the equine industry because of the fact that the mare does not respond to superovulation but can donate large numbers of oocytes through ovum pick up (OPU). After collection, the oocytes can be fertilized by intracytoplasmic sperm injection (ICSI) using a variety of stallion semen samples, even of poor quality, and the resulting embryos can establish high pregnancy rates after cryopreservation and transfer. The discoveries that equine oocytes can be held at room temperature without...
Fedorka CE, Murase H, Loux SC, Loynachan AT, Walker OF, Squires EL, Ball BA, Troedsson MHT.Maintaining yearly foal production is important for the economic success of the broodmare, and this requires breeding to occur as quickly postpartum as possible. The initial postpartum estrus occurs within 5-20 days postpartum, whereas the uterus is still undergoing repair from tissue alterations during pregnancy and parturition, a process known as involution. Attempts have been made to hasten this process, but with minimal success. Mycobacterium cell wall fraction (MCWF) is an immunomodulator that has been shown to reduce bacterial growth and alter aspects of the immune response to breeding,...
Ing NH, Konganti K, Ghaffari N, Johnson CD, Forrest DW, Love CC, Varner DD.It is not unusual for stallions to have fertility problems. For many, artificial insemination with more dense spermatozoa (isolated by density gradient centrifugation) results in greater pregnancy rates compared with the rates when using unfractionated spermatozoa. RNAs in spermatozoa delivered to the oocyte at conception are required for embryo development. Novel molecular assays of spermatozoa that reflect function are needed to predict the fertility of stallions. To describe and compare the RNA populations in more dense and less dense spermatozoa from stallions. Spermatozoa from five stalli...
Ousey JC.The endocrine profiles in the periparturient mares are dominated by increasing concentrations of progestagens and decreasing oestrogens. These hormones are produced by precursors from the foetus, metabolized by the placenta and act primarily on the maternal uterus. The circulating concentrations of hormones in maternal plasma, generally, represent a small proportion of those metabolized by the foetus and utero-placental tissues. There is clear evidence that the foetal hypothalamo-pituitary-adrenal (HPA) axis initiates the process of foetal maturation and the hormonal cascade which culminates i...
Ellington JE, Samper JC, Jones AE, Oliver SA, Burnett KM, Wright RW.Formation of a spermatozoa ('sperm') reservoir in the mare is thought to occur through lectin-mediated sperm attachment to the oviductal epithelium. Once attached, prefertilization sperm survival is supported by oviductal factors. Cryopreservation of stallion sperm decreases the number of sperm attaching to oviduct epithelial cells (OEC) and the length of time these sperm survive. Quantification of in vitro interactions between sperm and OEC in a co-culture system may provide an assay for functional integrity of cryopreserved or fresh sperm samples. Additionally, superior additives for in vitr...
Franciolli AL, Cordeiro BM, da Fonseca ET, Rodrigues MN, Sarmento CA, Ambrosio CE, de Carvalho AF, Miglino MA, Silva LA.In spite of numerous, substantial advances in equine reproduction, many stages of embryonic and fetal morphological development are poorly understood, with no apparent single source of comprehensive information. Hence, the objective of the present study was to provide a complete macroscopic and microscopic description of the equine embryo/fetus at various gestational ages. Thirty-four embryos/fetuses were aged based on their crown rump length (CRL), and submitted to macroscopic description, biometry, light and scanning microscopy, as well as the alizarin technique. All observed developmental c...
Rose BV, Firth M, Morris B, Roach JM, Wathes DC, Verheyen KLP, de Mestre AM.Therapeutic practices in equine reproductive medicine have dramatically evolved over the last 20 years but current usage is not described. The aims of this study were to provide a description of medication use and clinical findings of reproductive examinations alongside measures of reproductive efficiency in thoroughbreds. A prospective cohort study was conducted in the 2013 and 2014 breeding seasons. Mare and stallion details, information on veterinary interventions and findings of reproductive ultrasound scans were collected using questionnaires and entered into a custom-designed Microsoft A...
Silva LA, Klein C, Ealy AD, Sharp DC.This work examined how the conceptus modulates endometrial tissue remodeling and vascular development prior to implantation in mares. A macroscopic uterine examination was completed at day 21 of pregnancy. In situ morphology revealed that the endometrium involved in encroachment is restricted to the dorsal endometrium immediately overlying the yolk sac. The amount of stromal area occupied by blood vessels and the number of endometrial glands were increased during early pregnancy. Endometrial histomorphometry as well as the endometrial mRNA abundance and immunolocalization of VEGF, VEGFR1, VEGF...
Wood PL, Ball BA, Scoggin K, Troedsson MH, Squires EL.Amniotic fluid is essential for the growth and maturation of the fetus prior to parturition. While our knowledge of human amniotic fluid is extensive, current data for equine amniotic fluid is limited. We therefore undertook a detailed lipidomics analysis of equine amniotic fluid. Using a non-targeted high-resolution mass spectrometric lipidomics analysis of equine amniotic fluid, we were able to characterize a diverse array of individual lipids. This non-biased analytical approach detected, for the first time, the presence of (O-acyl)-ω-hydroxy-fatty acids (OAHFA) with up to 52 carbon chain ...
Maischberger E, Irwin J, Carrington S, Duggan V.The deposition of semen, bacteria and debris in the uterus of the mare after breeding normally induces a self-limiting endometritis. The resultant fluid and inflammatory products are cleared by 48 hours post cover. Mares that are susceptible to persistent post-breeding endometritis (PPBEM) have impaired uterine defence and clearance mechanisms, making them unable to resolve this inflammation within the normal time. This persists beyond 48 hours post-breeding and causes persistent fluid accumulation within the uterus. Mares with PPBEM have an increased rate of embryonic loss and a lower overall...
Bailey E.The sera of 390 pregnant Standardbred mares and 409 pregnant Thoroughbred mares were tested for anti-red blood cell (RBC) antibodies. Of the Standardbred mares and Thoroughbred mares, 20% and 10%, respectively, had anti-RBC antibodies detectable in hemolytic or saline agglutination tests. Most of the antibodies were specific for the CA blood-group antigen of horses. Other antibodies were specific for the Aa, Ab, Aa, Ab, Da, Df, Ka, Ua, or Qa blood-group antigens. The occurrence of these antibodies in the serum and colostrum was compared for 268 mares. With 3 exceptions, whenever antibodies wer...
Bailey CS, Macpherson ML, Pozor MA, Troedsson MH, Benson S, Giguere S, Sanchez LC, Leblanc MM, Vickroy TW.The objective was to determine if long-term treatment with trimethoprim sulfamethoxazole (antimicrobial), pentoxifylline (anti-inflammatory/anti-cytokine) and altrenogest (synthetic progestin), would improve pregnancy outcome in mares with experimentally induced placentitis. Seventeen normal, pregnant pony mares were enrolled in the study at 280-295 d of pregnancy. Placentitis was induced in all mares by intra-cervical inoculation of Streptococcus equi subsp. zooepidemicus (10(7) CFU). Five mares served as infected, untreated control animals (Group UNTREAT). Twelve mares (Group TREAT) were inf...
Wernery U, Knowles NJ, Hamblin C, Wernery R, Joseph S, Kinne J, Nagy P.A virus was isolated from aborted dromedary (Camelus dromedarius) fetuses during an abortion storm in Dubai, United Arab Emirates. Laboratory investigations showed the causative agent to be indistinguishable from equine rhinitis A virus (ERAV), a picornavirus. Two pregnant dromedaries experimentally infected with the camel virus isolate both aborted and an identical virus was reisolated from both fetuses, thus confirming the diagnosis. The extremely high prevalence of antibody (>90 %) and the high titres recorded against ERAV in the dromedary herd clearly showed that ERAV does infect dromedari...
Portus BJ, Reilas T, Katila T.There is conflicting evidence over the role seminal plasma plays in sperm transport and inflammation within the uterus of mares. In in vitro studies, seminal plasma has been shown to reduce polymorphonuclear neutrophil (PMN) function, but the opposite effect on uterine inflammation has been reported in vivo. Objective: To study the effect of seminal plasma on uterine contractility, inflammation and pregnancy rates by inseminating mares with low doses of sperm free from seminal plasma (Group 1) and containing seminal plasma (Group 2). Methods: Synchronised mares were inseminated with 50 x 10(6)...
de Leon PM, Campos VF, Dellagostin OA, Deschamps JC, Seixas FK, Collares T.In this study, polymerase chain reaction (PCR) reamplification of the first PCR product (2nd-PCR) and a qPCR assay were used to detect the sex determining region Y (SRY) gene from circulating cell-free fetal DNA (ccffDNA) in blood plasma of pregnant mares to determine fetal sex. The ccffDNA was isolated from plasma of 20 Thoroughbred mares (5-13 y old) in the final 3 mo of pregnancy (fetal sex was verified after foaling). For controls, plasma from two non-pregnant mares and two virgin mares were used, in addition to the non-template control. The 182 bp nucleotide sequence corresponding to the ...
Smits K, Govaere J, Peelman LJ, Goossens K, de Graaf DC, Vercauteren D, Vandaele L, Hoogewijs M, Wydooghe E, Stout T, Van Soom A.The necessity for early interaction between the embryo and the oviductal and/or uterine environment in the horse is reflected by several striking differences between equine embryos that develop in vivo and those produced in vitro. Better understanding of the salient interactions may help to improve the efficiency of in vitro equine embryo production. In an initial experiment, cleavage-stage in vitro-produced (IVP) equine embryos were transferred into the uterus of recipient mares that had ovulated recently to determine whether premature placement in this in vivo environment would improve subse...
Kirkpatrick JF, Turner JW, Liu IK, Fayrer-Hosken R, Rutberg AT.Non-lethal management methods are required for wild equids that are protected by law and for deer inhabiting areas where lethal controls are not legal or safe. Single or multiple inoculations of porcine zona pellucida (PZP) vaccine have been delivered to wild horses and deer by means of darts. Contraceptive efficacy in horses after two inoculations ranged from 90% to 100%, and after a single inoculation ranged from 19% to 28%. Mares given a controlled-release form of the vaccine had foaling rates ranging from 7% to 20%. No detectable changes in social organization or behaviours among treated h...
Giesecke K, Hamann H, Stock KF, Klewitz J, Martinsson G, Distl O, Sieme H.The research of fertility in humans and other mammals has strongly advanced in the recent years. The examination of molecular mechanisms influencing horse fertility is relatively recent. We chose the angiotensin converting enzyme (ACE), the sperm autoantigenic protein 17 (SP17) and the follicle stimulating hormone (FSHB) as candidates for determining stallion fertility and to analyze associations of intragenic single nucleotide polymorphisms (SNPs), flanking microsatellites and candidate-gene linked haplotypes with the pregnancy rate per oestrus (PRO) in 179 Hanoverian stallions. Fertility tra...
Gastal MO, Gastal EL, Torres CA, Ginther OJ.A technique for transvaginal, ultrasound-guided intrauterine injection was developed. After preliminary study using different approaches, the procedure was successful in 24 of 25 (96%) mares, based on detecting fluid in the uterine lumen during and after the injection. The technique was used to study the effect of PGE2, reportedly produced by the embryonic vesicle, on uterine contractility on Day 12 (Day 0 = ovulation). Uterine contractility was scored (1 = minimal, 4 = maximal) every 10 min for 1 h and every 30 min for the next hour by a continuous 1-min ultrasound examination of a longitudin...
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 ...
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...
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...
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...
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...
