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.
Dini P, Carossino M, Loynachan AT, El-Sheikh Ali H, Wolfsdorf KE, Scoggin KE, Daels P, Ball BA.Hydrallantois is the excessive accumulation of fluid in the allantoic cavities during the last trimester of pregnancy, leading to abdominal wall hernias, cardiovascular shock, abortion, and dystocia. It has been postulated that hydrallantois is associated with structural and/or functional changes in the chorioallantoic membrane. In the present study, we hypothesized that angiogenesis is impaired in the hydrallantoic placenta. Capillary density in the hydrallantoic placenta was evaluated in the chorioallantois via immunohistochemistry for Von Willebrand Factor. Moreover, the expression of angio...
Prell MJ, McCue PM, Moffett PD, Graham JK.Breeding mares with cryopreserved semen requires specialized equipment for storage and thawing and more intensive mare management. The objectives of this study were (1) evaluate the longevity of frozen stallion semen once it had been thawed, extended, and maintained at 5°C for 48 hours in a passive cooling container, and (2) determine fertility potential of frozen semen that had been thawed, extended, and used to inseminate mares after 24 hours of cooled storage. Eight ejaculates were collected and aliquots were cooled in either INRA96 and CryoMax LE minus cryoprotectant at a concentration ...
Souza JRM, Gonçalves PBD, Bertolin K, Ferreira R, Ribeiro ASS, Ribeiro DB, Rechsteiner SMDEF, Araújo RR, Pimentel CA, Pimentel AMH.The aim of the present study was to evaluate the correlation of age and heat cycle to determine reproductive efficiency in young and aged Thoroughbred mares bred on foal heat (FH) or on second heat (SH) after foaling. Embryo mortality (EmbM) was determined every time a mare was found open after a positive pregnancy diagnosis. Parturition to breeding interval, pregnancy rate (PregR) and EmbM rate were the dependent variables and the treatments were breeding on the FH or on SH. The cutoff age to obtain above-average probability for the EmbM was 10 years old. PregR in mares bred on FH was lower ...
Antczak DF.The development of placentation that coincided with the evolution of mammals presented new challenges to the transmission of life from one generation to the next, particularly with regard to the possibility of maternal immunological recognition and destruction of the developing conceptus. The balance between immunity and tolerance dominates the immunological relationship between mother and fetus during mammalian pregnancy, and the focal point of this relationship lies at the interface between the trophoblast cells that comprise the outermost layer of the placenta and the maternal endometrial t...
Campos I, Batista B, Matos AC, Dutra F, Gomes G, Pinna A, Leite J, Ferreira A.The amnion is a layer of the foetal membrane that has mechanical protection function and allows expansion and growth. The diseases that affect amnion have rarely been reported in horses. Amnionitis and funiculitis have been implicated as components of abortions as observed in abortions caused by the mare reproductive loss syndrome. Here, we report an abortion at 240-day gestation of a 7-year-old Anglo-Arabian mare with a history of previous stillbirth. Blood samples from both mare and foetus were collected for serological testing. Fragments from the placenta were taken for macroscopic and hist...
Nagel C, Aurich J, Aurich C.Economic losses due to dystocia or neonatal death as well as animal welfare and ethical concerns demand a reliable prediction of parturition with the aim to improve survival of the dam and her offspring. In this review, estimation of gestational age by ultrasound and prediction of parturition based on clinical signs, behaviour changes and changes in body temperature, composition of mammary gland secretions as well as hormonal changes are discussed in comparison between horses and cattle. Based on the physiological changes associated with the end of gestation and onset of labor, several systems...
Pinto CRF.It has been more than a hundred years that studies aiming to elucidate the processes involved in cyclicity and pregnancy pointed out the requirement of ovaries and corpora lutea for embryo survival and pregnancy establishment. For horses, luteal progesterone is essential for pregnancy only during the first trimester. This progestational support is complex among domestic animals as ovarian luteal function is further enhanced by the LH-action role of equine chorionic gonadotropin (eCG) starting ∼ on Day 35 of pregnancy. Increased eCG secretion leads to the formation of supplementary corpora ...
El-Sheikh Ali H, Boakari YL, Loux SC, Dini P, Scoggin KE, Esteller-Vico A, Kalbfleisch T, Ball BA.The key event in placentitis-induced preterm labor is myometrial activation with the subsequent initiation of labor. However, the molecular mechanisms underlying myometrial activation are not fully understood in the mares. Therefore, the equine myometrial transcriptome was characterized during placentitis (290.0 ± 1.52 days of GA, n = 5) and the prepartum period (330 days of GA, n = 3) in comparison to normal pregnant mares (289.8 ± 2.18 days of GA, n = 4). Transcriptome analysis identified 596 and 290 DEGs in the myometrium during placentitis and the prepartum period, respectively...
Rapacz-Leonard A, Leonard M, Chmielewska-Krzesińska M, Siemieniuch M, Janowski TE.Despite their importance in mammalian reproduction, substances in the oxytocin-prostaglandins pathways have not been investigated in the horse placenta during most of pregnancy and parturition. Therefore, we quantified placental content of oxytocin (OXT), oxytocin receptor (OXTR), and prostaglandin E2 and F2 alpha during days 90-240 of pregnancy (PREG), physiological parturition (PHYS), and parturition with fetal membrane retention (FMR) in heavy draft horses (PREG = 13, PHYS = 11, FMR = 10). We also quantified OXTR and prostaglandin endoperoxide synthase-2 (PTGS2) mRNA expression ...
Miró J, Morató R, Vilagran I, Taberner E, Bonet S, Yeste M.Three separate experiments were conducted to improve preservation of stallion epididymal sperm. In the first one, two different cooling extenders (Kenney and Gent) were compared. Sperm viability and motility patterns were assessed in 10 different epididymal sperm samples after 0 hours, 24 hours, 48 hours, 72 hours, and 96 hours of preservation at 4°C. No significant differences were observed in any of the evaluated parameters either between extenders or throughout the storage period. The second set of experiments was designed to determine whether supplementing thawing medium (INRA Freeze...
Canisso IF, Loux SC, Lima FS.Placentitis is an important cause of abortion, stillbirth, and neonatal death in horses. The diagnosis of placentitis is based on occurrence of clinical signs (premature mammary gland development and vulvar discharge) and ultrasonography of the caudal placental pole. However, early and subtle cases can be missed. In the last few years, several studies have provided objective means of diagnosing placentitis in mares with single or serial measurements of blood markers. Among the markers evaluated the steroids produced by the fetoplacental unit have been shown to change in association with placen...
El-Sheikh Ali H, Legacki EL, Scoggin KE, Loux SC, Dini P, Esteller-Vico A, Conley AJ, Stanley SD, Ball BA.Equine placentitis is associated with alterations in maternal peripheral steroid concentrations, which could negatively affect pregnancy outcome. This study aimed to elucidate the molecular mechanisms related to steroidogenesis and steroid-receptor signaling in the equine placenta during acute placentitis. Chorioallantois (CA) and endometrial (EN) samples were collected from mares with experimentally induced placentitis (n = 4) and un-inoculated gestationally age-matched mares (control group; n = 4). The mRNA expression of genes coding for steroidogenic enzymes (3βHSD, CYP11A1, CYP17A1, CYP19...
Hannan MA, Haneda S, Murata K, Takeuchi S, Cheong SH, Nambo Y.Until now, there have been no reports of foals born through embryo transfer after artificial insemination using frozen semen in Japan. The aims of this study were to develop a riding crossbred horse and evaluate the prospects of embryo transfer technology in multiplying horse population. In both donor and recipient mares, luteolysis was induced by the administration of 0.1 mg Cloprostenol to synchronize the onset of estrus, and ovulation was induced by administering 2000 IU human chorionic gonadotropin (hCG) or 0.75 mg Deslorelin. Frozen semen from an Irish Connemara pony stallion was used to ...
Pennington PM, Splan RK, Jacobs RD, Chen Y, Singh RP, Li Y, Gucek M, Wagner AL, Freeman EW, Pukazhenthi BS.Insulin resistance (IR) is characterized by an increase in biomarkers of systemic inflammation and susceptibility to laminitis in horses. Impacts on reproduction include a lengthened interovulatory period in horses. Dietary omega-3 (docosahexaenoic acid [DHA]) promotes anti-inflammatory processes, has been implicated in health benefits, and can reduce cytokine secretion. This preliminary study investigated the impact of IR as well as the influence of dietary supplementation (DHA) on the uterine fluid proteome in early pregnant horses. Mares were artificially inseminated; uterine fluid and embr...
Jeannerat E, Marti E, Thomas S, Herrera C, Sieme H, Wedekind C, Burger D.The major histocompatibility complex (MHC) influences sexual selection in various vertebrates. Recently, MHC-linked social signaling was also shown to influence female fertility in horses (Equus caballus) diagnosed 17 days after fertilization. However, it remained unclear at which stage the pregnancy was terminated. Here we test if MHC-linked cryptic female choice in horses happens during the first days of pregnancy, i.e., until shortly after embryonic entrance into the uterus and before fixation in the endometrium. We exposed estrous mares to one of several unrelated stallions, instrumentally...
Mirra A, Birras J, Diez Bernal S, Spadavecchia C.Epidural administration of morphine has been shown to be an effective analgesic strategy in horses; however, the possible occurrence of side effects limits its usage. In order to decrease their frequency, it is important to target the minimal effective plasma concentration and avoid overdosing. As to date species-specific pharmacokinetics data are not available for epidural morphine, the dosing regimen is usually established on the basis of clinical reports and personal experience. In certain physiological conditions, like gestation, the outcome of an empirical dosing scheme can be unpredictab...
Angel D, Canesin HS, Brom-de-Luna JG, Morado S, Dalvit G, Gomez D, Posada N, Pascottini OB, Urrego R, Hinrichs K, Velez IC.Effects of meiotic stage and cumulus status on development of equine oocytes after vitrification was evaluated. Immature oocytes with corona radiata (IMM); in vitro-matured oocytes with corona radiata (MAT CR+); and in vitro-matured oocytes denuded of cumulus (MAT CR-) were vitrified using the Cryotech® method. Warming medium was equilibrated either in 5% CO2 or Air. IMM oocytes underwent in vitro maturation after warming. Recovery, survival, and maturation rates, and cleavage and blastocyst rates after ICSI, were evaluated. Recovery was higher for oocytes warmed in CO2- than Air-equilibrated...
Nieto-Olmedo P, Martín-Cano FE, Gaitskell-Phillips G, Ortiz-Rodríguez JM, Peña FJ, Ortega-Ferrusola C.In order to determine whether differences in uterine blood flow between pregnant and non-pregnant mares can be used to predict the presence of the equine embryo prior to flushing in an embryo transfer program, power Doppler ultrasonography was used on a total of 52 mares on days 7 or 8 post-ovulation. Computer analysis of Doppler images was subsequently performed using ImageJ v1.48 software. Vascular perfusion of the endometrium was analyzed using spot meter techniques, measuring mean pixel intensity and area of blood flow. Mares with positive flushings presented a higher uterine blood flow ar...
Smits K, Gansemans Y, Tilleman L, Van Nieuwerburgh F, Van De Velde M, Gerits I, Ververs C, Roels K, Govaere J, Peelman L, Deforce D, Van Soom A.The signal for maternal recognition of pregnancy (MRP) has still not been identified in the horse. High-throughput molecular biology at the embryo-maternal interface has substantially contributed to the knowledge on pathways affected during MRP, but an integrated study in which proteomics, transcriptomics and miRNA expression can be linked directly is currently lacking. The aim of this study was to provide such analysis. Endometrial biopsies, uterine fluid, embryonic tissues, and yolk sac fluid were collected 13 days after ovulation during pregnant and control cycles from the same mares. Micro...
Immonen I, Cuervo-Arango J.The reproductive management of mares for frozen semen artificial insemination (AI) can be costly and labor intensive. Predicting the exact time of ovulation can be challenging even when ovulation-inducing drugs are used. The main objective of this retrospective study was to determine whether there was an effect of interval between examinations to detect ovulation on likelihood of pregnancy and early embryonic loss in mares after postovulatory breeding with a single straw of frozen/thawed semen. The second objective was to determine the efficacy of two different drugs (human chorionic gonadotro...
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...
Dini P, El-Sheikh Ali H, Carossino M, C Loux S, Esteller-Vico A, E Scoggin K, Daels P, A Ball B.Equine chromosome 24 microRNA cluster (C24MC), the ortholog of human C14MC, is a pregnancy-related miRNA cluster. This cluster is believed to be implicated in embryonic, fetal, and placental development. The current study aimed to characterize the expression profile of this cluster in maternal circulation throughout equine gestation. The expression profile of miRNAs belonging to this cluster was analyzed in the serum of non-pregnant (diestrus), pregnant (25 d, 45 d, 4 mo, 6 mo, 10 mo), and postpartum mares. Among the miRNAs examined, 11 miRNAs were differentially expressed across the analyzed ...
Hannan MA, Murata K, Takeuchi S, Haneda S, Cheong SH, Nambo Y.The objectives of this study were to determine the plasma profile of equine chorionic gonadotropin (eCG) and its association with the formation of supplementary corpus luteum (CL) and plasma progesterone concentrations in embryo transfer Hokkaido native pony recipient mares. Blood samples and transrectal ultrasound examination of the reproductive tract were carried out weekly from the day of ovulation until week 32 of gestation (n = 4). Plasma concentrations of eCG and progesterone were measured by enzyme immunoassays. The eCG concentration was first detectable at week 5 for 2 mares and at wee...
Dordas-Perpinyà M, Pintart C, Terris H, Normandin L, Bruyas JF.Two cloned mares, produced from the same sample of skin fibroblasts, were bred during four breeding seasons from their second year of age, as embryo donors, in exactly the same conditions, using the same stallions for both cloned mares. The aim of this study was to test the embryo donor potential of cloned mares and to compare the results obtained from two cloned mares of the same mare with other embryo donor mares (n = 31-39 per breeding season) at the same stud. For both cloned mares, 19 embryos were recovered by 43 collection attempts (44%) (7/22 for one; 12/21 for the other), 16 (84%) pr...
Denys M, Thomas-Cancian A, Tortereau A, Josson-Schramme A, Buff S.Premature udder development constitutes an alarm signal in pregnant mares. The objective of this clinical case report is to highlight the importance of transabdominal ultrasound examination of the fetus in these cases and to report a unique case of prenatal diagnosis of obstructive uropathy based on the observation of severe fetal hydronephrosis and megacystitis in utero. A 4-year-old French chaser primiparous mare was referred for evaluation of premature udder development during the ninth month of pregnancy. The mare had clinical signs within normal limits, a developed and sensitive udder wit...
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...
Podico G, Canisso IF, Roady PJ, Austin SM, Carossino M, Balasuriya U, Ellerbrock RE, Lima FS, Ferreira-Dias G, Douglas RH.Pregnancy loss during the normal lifespan of endometrial cups (∼37-120-150 days of gestation) may affect a mare's ability to conceive again in the same breeding season, as equine chorionic gonadotropin (eCG) secretion by retained endometrial cups can lead to abnormal ovulations and follicular growth. While intrauterine kerosene infusion has anecdotally been proposed as a treatment for endometrial cup retention, there are no controlled studies evaluating kerosene's ability to enhance endometrial cup regression following abortion. The objectives of this study were to assess uterine response, s...
Jinglong X, Xiaobin L, Fang Z, Chenchen W, Kailun Y.The aim of this research was to isolate bacteria capable of biotransforming daidzein from fresh feces from pregnant horses. A Hungate anaerobic roller tube was used for anaerobic culture. Single colonies were picked at random and incubated with daidzein. High performance liquid chromatography was used to detect whether the isolated bacteria were able to biotransform the substrate. A strain capable of reducing daidzein was selected and characterized using sequence analysis of 16S rDNA, and a phylogenetic tree was constructed. The morphological physiological and biochemical characteristics of th...
Krakowski L, Brodzki P, Krakowska I, Opielak G, Marczuk J, Piech T.The aim of the study was to determine the level of prolactin (PRL), serum amyloid A (SAA), and selected biochemical markers (T-Chol, AST, TP, Mg, P, and Ca) in the blood of mares during the perinatal period. The study involved 14 mares of the Polish Coldblood Horse breed, which were in the third trimester of pregnancy. Blood was collected for testing 2 weeks before parturition and then 24 hours after delivery and in the foal heat (9 days) and 9 days after ovulation and breeding. The research revealed significant differences in the level of PRL and SAA before and after delivery. The highest...
Loux SC, Dini P, El-Sheikh Ali H, Kalbfleisch T, Ball BA.The placenta is a dynamic organ which undergoes extensive remodeling throughout pregnancy to support, protect and nourish the developing fetus. Despite the importance of the placenta, very little is known about its gene expression beyond very early pregnancy and post-partum. Therefore, we utilized RNA-sequencing to characterize the transcriptome from the fetal (chorioallantois) and maternal (endometrium) components of the placenta from mares throughout gestation (4, 6, 10, 11 m). Within the endometrium, 47% of genes changed throughout pregnancy, while in the chorioallantois, 29% of genes under...
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...
Kammerer R, Ballesteros A, Bonsor D, Warren J, Williams JM, Moore T, Dveksler G.In early equine pregnancy, a highly invasive trophoblast cell subpopulation, the chorionic girdle cells, invade the endometrium and form endometrial cups (EC). These cells express classical MHC molecules, thereby stimulating a humoral and cellular immune response, resulting in a massive accumulation of maternal CD4+ and CD8+ T cells around the EC. Nevertheless, no immediate destruction of endometrial cups by maternal lymphoid cells occurs, presumably due to immune tolerance. Although the environment of EC is rich in TGFB and in FOXP3+, CD4+ T cells, the mechanisms leading to tolerance have not...
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...
Cole JR, Hall RF, Gosser HS, Hendricks JB, Pursell AR, Senne DA, Pearson JE, Gipson CA.A group of 14 pregnant mares was exposed via contact to 4 mares bred to stallions infected with equine viral arteritis virus. There was a demonstrable febrile response in each donor mare and in 12 of the pregnant mares. All 18 mares became seropositive after exposure. Equine viral arteritis virus was isolated from the nasopharynx of 5 pregnant mares, but not from the donor mares. Ten of the pregnant mares aborted, and virus was isolated from fetal specimens or placenta of 8.
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 ...
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 ...
Watson TD, Burns L, Packard CJ, Shepherd J.The incidence of hyperlipaemia in ponies is highest in mares in late gestation and then early in lactation. Plasma lipid and lipoprotein concentrations were measured to establish the metabolic basis for this and the lipoprotein composition of six healthy Shetland ponies was analysed before pregnancy, in the last six weeks of gestation and one month after foaling. In the pregnant ponies, the concentrations of cholesterol and triglyceride were significantly increased (both P < 0.05) because of increased concentrations of high density lipoproteins (HDL) and very low density lipoproteins (VLDL)...
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...
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 ...
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...
Donaldson WL, Oriol JG, Plavin A, Antczak DF.Between days 36-38 of pregnancy equine trophoblastic cells of the chorionic girdle migrate and form endometrial cups. Just prior to invasion, the chorionic girdle cells express high levels of polymorphic, paternally inherited, major histocompatibility complex (MHC) class I antigens. Their descendents, the mature, invasive trophoblast cells of the endometrial cups, however, express low or undetectable levels of MHC class I antigens by day 44 of pregnancy. Experiments with MHC compatible pregnancies, the study of residual chorionic girdle cells that had failed to invade the endometrium and remai...
Bondo T, Jensen SK.This study assessed the effect of a vitamin E supplement given to pregnant mares on immunoglobulins (Ig) levels in foals. In addition, the fatty acid (FA) content and composition of the mares' milk was assessed. Milk α-tocopherol concentrations were compared between pregnant Danish Warmblood mares (n = 17) given a daily oral supplement of 2500 international units (IU) RRR-α-tocopherol in the last 4 weeks of pregnancy and a group of unsupplemented mares (n = 17) receiving 170-320 IU vitamin E daily originating from the feed. Milk α-tocopherol was higher in supplemented mares (36.7, 12.4 and ...
Loux SC, Scoggin KE, Bruemmer JE, Canisso IF, Troedsson MH, Squires EL, Ball BA.MicroRNAs (miRNAs) are small, non-coding RNAs which are produced throughout the body. Individual tissues tend to have a specific expression profile and excrete many of these miRNAs into circulation. These circulating miRNAs may be diagnostically valuable biomarkers for assessing the presence of disease while minimizing invasive testing. In women, numerous circulating miRNAs have been identified which change significantly during pregnancy-related complications (e.g. chorioamnionitis, eclampsia, recurrent pregnancy loss); however, no prior work has been done in this area in the horse. To identif...
Gibson C, de Ruijter-Villani M, Rietveld J, Stout TAE.Glucose is the primary energy substrate for early conceptus development and, for the first 40 days of gestation, the equine conceptus depends solely on glucose available in the histotroph; thereafter, histotrophic glucose provision continues to support transport across the definitive placenta. To investigate glucose provision routes during early equine pregnancy we examined expression of glucose transporters in conceptus membranes and endometrium recovered on days 7, 14, 21 and 28 after ovulation. To further differentiate the contributions of maternal progesterone priming and conceptus-endomet...
Cortez JV, Hardwicke K, Cuervo-Arango J, Grupen CG.The cloning of horses is a commercial reality, yet the availability of oocytes for cloned embryo production remains a major limitation. Immature oocytes collected from abattoir-sourced ovaries or from live mares by ovum pick-up (OPU) have both been used to generate cloned foals. However, the reported cloning efficiencies are difficult to compare due to the different somatic cell nuclear transfer (SCNT) techniques and conditions used. The objective of this retrospective study was to compare the in vitro and in vivo development of equine SCNT embryos produced using oocytes recovered from abatt...
Galli C, Lagutina I, Duchi R, Colleoni S, Lazzari G.The cloning of equids was achieved in 2003, several years after the birth of Dolly the sheep and also after the cloning of numerous other laboratory and farm animal species. The delay was because of the limited development in the horse of more classical-assisted reproductive techniques required for successful cloning, such as oocyte maturation and in vitro embryo production. When these technologies were developed, the application of cloning also became possible and cloned horse offspring were obtained. This review summarizes the main technical procedures that are required for cloning equids an...
Woods J, Bergfelt DR, Ginther OJ.The effects of pre-ovulatory and post ovulatory insemination on pregnancy rate and embryonic-loss rate were studied in 268 mares in two experiments. Within each experiment mares were randomised within replicates as follows: to be inseminated on the day the pre-ovulatory follicle reached 35 mm (pre-ovulatory group), to be inseminated on the day of ovulation (Day 0 group), and to be inseminated on the day after ovulation (Day 1 group). Ultrasonic pregnancy diagnoses were performed on Days 11, 12, 13 and 14 (Experiment 1) and Days 11, 12, 13, 14, 15, 20 and 40 (Experiment 2). Combined for the two...
Woods GL, Baker CB, Baldwin JL, Ball BA, Bilinski J, Cooper WL, Ley WB, Mank EC, Erb HN.During 1985, linear-array ultrasonography was used to study early pregnancy loss in commercial brood mares: 600/1115 (54%) of the cycles resulted in detected pregnancy at Week 2 after ovulation and 80 (13%) of these pregnancies resulted in early pregnancy loss. The pregnancy loss rate was significantly higher (P less than 0.05) for twin pregnancies (10/41) than for singleton pregnancies (70/559). The pregnancy loss rate was significantly higher (P less than 0.05) at 2-4 weeks (29/60) than at 6-8 weeks (12/60). The pregnancy rate was significantly less (P less than 0.05) for post-partum mares i...
Peugnet P, Robles M, Wimel L, Tarrade A, Chavatte-Palmer P.The study of early developmental conditioning of health and disease in adulthood is particularly relevant in the horse, which is bred mainly to perform in demanding sport challenges. On the basis of this concept, the management of the broodmare could be considered an effective means to produce animals with the desired features. Knowledge on the Developmental Origins of Health and Disease in the equine species remains relatively scarce, with some experimental studies and one single epidemiologic study. Data highlight the determinant role of the maternal environment for postnatal body conformati...
Esteller-Vico A, Ball BA, Troedsson MHT, Squires EL.Equine pregnancy is characterized by very high circulating concentrations of estrogens. The physiological roles of estrogens during equine gestation are largely unknown, although some studies suggest a role in the regulation of uterine artery hemodynamics and a relationship between low circulating estrogen concentrations and late pregnancy loss. The objectives of this experiment were to evaluate the effects of estrogen suppression on uterine artery hemodynamics and on pregnancy outcome. Estrogen synthesis was suppressed using letrozole, a potent aromatase inhibitor. Twelve pregnant mares were ...
Ganjam VK, Evans TJ.Endometrial periglandular fibrosis (EPF) contributes to embryonic and fetal loss in mares. Equine EPF correlates inversely with conception and successful gestation. In the modified Kenney endometrial biopsy classification system, EPF categories I, IIA, IIB, and III correspond to minimal, mild, moderate, and severe fibrosis (+/-inflammation), respectively. Paraffin sections of biopsy specimens were stained with H&E, and picrosirius red (specific for fibrillar collagens types I and III), to determine %EPCVF. Endometrial ACE-binding activity, TGF-beta1 and 11beta-HSD2 activities were also measure...
