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.
Barrantes Murillo DF, Camillo G, Souza Serrano B, Almeida Luciano LP, Castilho Bichara GV, Chaves Vás CA, Furlan Gouvêa FH, Brandini Nespoli PE....Facial abnormalities and brain defects in aborted equine fetuses are rarely reported, and the causes that predispose the occurrence of this condition are difficult to identify. This work reports the morphological and tomographic findings of a case of cryptophthalmia, microphthalmia, oronasal malformation, and hydrocephalus in an aborted equine fetus with umbilical cord torsion in the state of Mato Grosso, Brazil, from a primiparous Quarter Horse female, with 7 months of gestational age. The occurrence of miscarriage was associated with compromised maternal-fetal blood flow due to umbilical cor...
Çortu A, Çınar H.Rectal examination is routine in equine reproduction but may trigger acute stress affecting welfare and safety. Intraocular pressure (IOP) responds rapidly to autonomic changes and may capture short-lived stress responses. Objective: To evaluate whether rectal examination acutely affects IOP and behavioral responses in mares, and whether reactions differ by reproductive status. Methods: Twenty Rahvan mares (10 pregnant, 30-40 days' gestation; 10 non-pregnant; 4-7 years) underwent transrectal examination without sedation. IOP was measured bilaterally at six time points: 2 min pre-exam (T1), dur...
Verstraete MH, Norris JK, Loux SC, De Spiegelaere W, Carossino M, Daels P, Dini P.The placenta mediates critical interactions between mother and offspring that guide development and impact long-term health. Despite its importance, the cellular organization of the equine (Equus caballus) placenta remains poorly defined. The equine epitheliochorial placenta, characterized by the absence of trophoblast invasion and prominent endocrine activity, provides a unique comparative model for studying placental cellular composition and development. Methods: We applied single-cell RNA sequencing to chorioallantois tissue collected from first-trimester (n = 1) and term (n = 2) equine...
Equine chronic degenerative endometritis (CDE) is a progressive process characterized by endometrial fibrosis that could be responsible for alterations of uterine environment and foetal-maternal communication. Objective: The aim of this study was to try to restore this communication by intrauterine administrations of amniotic cell-derived extracellular vesicles (AMC-EVs) in a case series. Methods: Twelve mares were selected on the basis of their reproductive history of early embryonic loss or abortion and clinical suspicion of CDE subsequently verified with histopathological examination of end...
Scoggin KE, Rakha SI, Abdellatif AM, Adlan F, Helmy YA, Ruby R, Ball B, Boakari Y, Ali HE.Ascending placentitis is a significant cause of equine pregnancy loss, yet the upstream inflammatory triggers are poorly defined. Recently, we identified S100A8/S100A9 (S100A8/A9) alarmins as potential upstream regulators in a chronic equine placentitis model. The current study aimed to determine whether this upregulation is sustained in the acute model and in clinical cases, and to elucidate the expression of their downstream inflammatory mediators. Using an experimental model, we quantified mRNA expression in acute ( = 5) and chronic ( = 6) placentitis induced by ssp. . We found mRNA expre...
The research aims to study the dynamics of reproductive system pathologies in mares of Kazakh and Mugalzhar horse breeds and their impact on the reproductive traits of the breeding stock. The object of the research was horses of the Kazakh and Mugalzhar breeds. The formation of experimental groups was carried out using the pair-analog method. It was found that the frequency of detection of infertile mares is 13.8-25.0%. Subinvolution of the uterus from the total number of infertile mares is 8.3-10.7%, endometritis - 16.6-23.3%, atony and hypotonia of the uterus - 8.3-13.3%, ovarian diseases - ...
Cui B, Liu Y, Wu X, Li X.The objective of this study was to evaluate the effects of exogenous GnRH administration at the beginning of estrus synchronisation in mares during the spring transitional period. Estrus was synchronised using a progesterone releasing intravaginal device (PRID). The PRID was left in the vagina for 10 days, followed by an injection of 0.4 mg of cloprostenol at PRID removal. The GnRH group (n = 32) was subjected to intramuscular administration of 100 μg of the GnRH agonist triptorelin at PRID insertion, while the control group (n = 32) received 1 mL of sterile physiological sali...
Ramsaran LN, Byron M, Parry S, Lection J, Back B, Grenier J, Cheong SH, Diel de Amorim M.Real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR) is a technique that allows for the semi-quantification of mRNA transcripts present within a tissue of interest. Differences in the relative abundance of mRNA between samples detected by RT-qPCR require normalization with a reference gene or genes whose transcript abundance is stable within the tissue of interest independent of experimental conditions. In the field of equine reproductive studies, ACTB, GAPDH and B2M genes are the most widely used as reference genes for the normalization of RT-qPCR results. However,...
Moroni R, Fanelli D, Maltinti S, Orefice M, Rota A, Camillo F, Melanie P, Cantile C, Miragliotta V, Pirone A, Lazzarini G, Passamonti F, Marmorini P....Equine persistent breeding-induced endometritis can lead to chronic uterine inflammation and fibrosis, reducing fertility. Intrauterine ozone (O₃) has recently been proposed as a potential treatment for mares unresponsive to conventional therapies. This case series describes O₃ treatment in eleven mares barren for at least one year despite multiple inseminations attempts. During the first oestrous cycle, low-volume uterine lavage and endometrial biopsy were performed, followed by 3 consecutive days of intrauterine O₂-O₃ gas insufflation. In the subsequent cycle, both procedures were re...
Bueno VLC, Bastos HBA, Centeno LAM, Schmitt F, Larentis G, Mattos RC, Fiala-Rechsteiner S.The seminal plasma (SP), a fluid originating from the testes, epididymis, and accessory sex glands, represents 98 % of the volume of stallion ejaculate. Metabolomic analysis enables the identification of final products of metabolic pathways, providing insights into reproductive physiology. Objective: This study aimed to investigate the metabolomic profile of stallion seminal plasma and to investigate metabolic differences between stallions with high and low pregnancy rates, in order to identify potential biomarkers associated with fertility. Methods: Twenty-four Criollo stallions, were sampled...
Ledeck J, Dubrowski T, Schoumacher M, Peeters S, Le Goff C, Egyptien S, Deleuze S, Cavalier E, Ponthier J.Refined profiling of conjugated estrogens and androgens during equine pregnancy using liquid chromatography-tandem mass spectrometry (LC-MS/MS) could provide accurate fetal-sex determination. Current methods for fetal-sex prediction remain limited by timing, accuracy, and operator expertise. This study investigated sex-specific differences in maternal conjugated steroid profiles to develop a reliable, non-invasive predictive method. Samples were collected from 141 mares of various breeds starting at sixteen weeks of pregnancy. The samples were pooled according to gestational stage, divided int...
Cooper CJ, Arroyo LG, Hammermueller JD, Botts MM, Pearl DL, Wootton SK, Lillie BN.Equine herpesvirus-1 (EHV-1) is ubiquitous in the horse population, but prevalence estimates have ranged from 3 to 88% depending on the population and method of sampling. No prevalence studies have been carried out in Ontario, Canada. The objective of this study was to measure the prevalence of EHV-1 shedding in healthy broodmares in Ontario. A total of 381 mares from 42 farms in Ontario were sampled, including pregnant and barren broodmares. Samples were collected from the nose, vagina, and blood of each mare up to 6 times from December 2016 through October 2017 using a cross-sectional study ...
Eskandari G, Ahmadi Sheikhsarmast S, Ghasemi S, Mohri M.Neutrophil gelatinase-associated lipocalin (NGAL) is a glycoprotein involved in immune responses and inflammation, with established diagnostic utility in acute kidney injury (AKI) and systemic diseases. However, reference values for NGAL in healthy horses, particularly the Turkmen breed, remain poorly defined. Objective: This study aimed to establish reference values for serum NGAL concentrations in healthy Turkmen horses and to evaluate the influence of age, sex, pregnancy status and physical activity on its levels, as well as its correlations with haematological and serum biochemical variabl...
Risvanli A, Salykov R, Timurkaan N, Seker I, Ekinci E.This study was conducted to examine glandular histological changes in the uterus of Kyrgyz breed mares during the first 6 months of pregnancy. The study used 53 Kyrgyz breed mares; 43 of these were at different stages of pregnancy, while 10 were non-pregnant mares. Uterine samples obtained at the slaughterhouse were evaluated histomorphometrically; endometrial thickness, gland density, gland epithelial height and gland diameter were measured. In conclusion, it was concluded that in Kyrgyz mares, endometrial thickness, glandular epithelial height and diameter increased as pregnancy progressed...
Dantas FTDR, Canisso IF, Feijó LS, de Vasconcelos PMF, Campos ML, Ulanov AV, Li Z, Pizzi GLBL, Nogueira CEW, Curcio BR.Doxycycline is widely used in equine medicine, yet data on its pharmacokinetics and safety during late gestation are scarce. We investigated the pharmacokinetics, fetoplacental diffusion, and safety of compounded oral doxycycline in late-term pregnant mares. In the first experiment, six mares at 300 days of gestation received a single oral dose (10 mg/kg), and plasma concentrations were measured using LC-MS/MS. Pharmacokinetic analysis using non-compartmental and compartmental models showed rapid absorption, with a mean Cmax of about 6000 ng/mL reached within 0.8 h and a terminal half-life ...
Satué K, Fauci D, Fazio E, Velasco-Martínez MG, Bruschetta G, Medica P.This study investigates sequential changes in serum protein fractions during gestation in 31 pregnant Spanish Purebred mares compared to 15 non-pregnant control. Total serum proteins (TSP) were measured using the Biuret method, while albumin (ALB), total globulins (tGLOB), and their subfractions (α₁, α₂, β₁, β₂, γ-GLOB) were analyzed by agarose gel electrophoresis. Pregnant mares showed significant changes in serum protein profiles throughout gestation. TSP and tGLOB concentrations increased from mid to late pregnancy (months 6-11), while ALB concentrations declined between months...
Aiche S, Chikhaoui M, Smail F, Benamor N, Benia AR.Pregnancy causes increased oxidative stress in mares, possibly harming both the mare and the foal, whereas the effects of different exercise levels on oxidative stress and lipid metabolism during pregnancy remain unclear. Objective: For this reason, the aim of this research was to explore the impacts of different training intensities on oxidative stress and lipid metabolism during pregnancy. Methods: The study comprised 22 clinically normal Purebred Arabian mares from Algeria, which were divided into three groups according to age and exercise frequency. Blood samples were collected during both...
Tainturier D, Tainturier B, Michaud S, Briand-Amirat L, Topie E, Moreno D.A total of 147 mares of different breeds (110 were sport or race horses, often very valuable) have been monitored over 5 years from 2012 to 2016. When at or near term, the mares were monitored in order to induce foaling, by checking the mammary development by palpation, analysing the colour and consistency of the precolostrum, estimating the calcium and antibodies concentrations in the precolostrum and by measuring the plasmatic progestagens concentration every day at 6 p.m. At the end of gestation, it has been observed that the progestagens rate levelled off (the top concentration varies from...
van Heule M, Verstraete M, Norris JK, Graniczkowsa KB, Scoggin KE, Ali HE, Ball BA, De Spiegelaere W, Daels P, Weimer BC, Dini P.Nocardioform placentitis (NP) is an understudied form of equine placentitis historically attributed to nocardioform bacteria, yet it remains uncertain whether these organisms are the sole pathogens involved. Objective: To elucidate the pathophysiology of NP and the host-pathogen interaction. Methods: In vivo clinical multi-omics study. Methods: Dual RNA sequencing was performed to profile transcriptionally active microbial communities and concurrent placental transcriptome responses in samples from 31 placentas with and without NP. Untargeted metabolomics was performed to study the associated ...
McLachlan AD, Woolford L.Chlamydia psittaci was detected by real-time PCR in the lung, liver and kidney of an equine foetus that had aborted in South Australia in August 2023. The corresponding microscopic lesions included lymphocytic and histiocytic chorionitis, necrosis of placental villi associated with bacteria in the cytoplasm of trophoblastic epithelial cells, and multiple microgranulomas in the liver. Equine chlamydial abortion had not been diagnosed previously in South Australia. Eight days after examining the foetus and placenta, the veterinary pathologist developed fever and subsequently was admitted to hosp...
Miguel EL, Carneiro MFL, Griffo ALC, Baatsch Nascimento F, Dória RGS, Corrêa RR, Celeghini ECC.Vaginal varicosities in mares are rarely reported, although considered relatively common. Clinical recognition can be challenging, especially during early pregnancy, due to the intermittent nature of the bleeding. This report aims to describe the diagnostic approach, clinical evolution, and treatment of a case of vaginal varicosity in a pregnant mare, emphasizing a practical and minimally invasive method. A 9-year-old Brazilian Sport Horse mare with intermittent vaginal hemorrhage underwent clinical evaluation, showing no abnormalities. Vaginoscopy with a rigid endoscope revealed varicose vein...
Ali A, Derar DR, Alaeyeari AA, Alharbi YM.This study aimed to monitor intrauterine fetal growth, establish predictive equations for gestational age estimation, and determine the optimal period for fetal sexing in Arabian horses using ultrasonography. Unassigned: Seven Arabian mares were monitored from insemination to parturition using transrectal ultrasonography. The following fetal and embryonic parameters were measured: embryonic vesicle (EV), crown-rump length (CRL), biparietal diameter (BIP), stomach diameter (STD), chest depth (CHD), abdominal diameter (ABD), kidney length (KDL), eyeball diameter (EBD), and eye lens length (ELL)....
Feijo LS, Ledeck J, Wolfsdorf K, Ponthier J, Parry S, Felippe MJB.Associations between the immune and endocrine systems during equine pregnancy remain poorly understood. Based on the hypothesis that distinct phases of the equine healthy gestation are characterized by specific associations between circulating immunological and hormonal parameters, contributing to pregnancy maintenance, this investigation aimed to: (i) evaluate how circulating immunological and hormonal parameters change across different phases of pregnancy; (ii) investigate associations between changes in circulating immunological and hormonal parameters; and (iii) propose potential hormonal ...
Roxon CA, Deacon LJ, Abraham M, Stefanovski D, Sertich PL.Gestation length is not a reliable indicator of fetal maturity due to the variability of normal gestation length in the mare. A standard method to accurately predict equine fetal maturity is not being used clinically. The presence of continuous gastrointestinal peristalsis, as detected ultrasonographically, is an indicator that both human and canine fetuses are mature (can survive after elective cesarean section). To determine if continuous gastrointestinal peristalsis, which we termed Phase 5, was a valid indicator of fetal maturity in the horse, and whether this indicator varied in late-gest...
Boakari Y, El-Sheikh Ali H, Almeida GHDR, Scoggin KE, Fernandes CB, Marchio SP, Troedsson MHT, Carreira ACO.Equine placental dysfunction impairs fetal growth and disrupts pregnancy outcomes. Despite many advances in diagnosis, the molecular pathophysiology of equine placentitis and premature placental separation remains poorly understood. However, the hypoxia-inducible factor (HIF-α) pathway is related to placental hypoxia, and its modulation in placental diseases has been shown in other species. Therefore, we hypothesized that in conditions marked by equine placental dysfunction, oxygen deprivation in the chorioallantois membrane triggers the activation of the HIF-α pathway, which is related to m...
Khan Y, Gautier C, Aurich C, El-Shalofy A.Letrozole is a potent and highly selective third-generation aromatase inhibitor. In the present study, we aimed to investigate the effects of letrozole treatment of non-pregnant mares on estrous cycle characteristics. Cyclic, non-lactating mares (n = 9) were included. After estrus synchronization, mares were monitored to detect ovulation (d0:) of the treatment cycle. Each three mares were randomly assigned to one of three treatments: control, 0.5, and 1 mg/kg body weight letrozole in three consecutive cycles (d7 to d13 of the treatment cycle). Mares were inseminated in the estrus after trea...
de Lara NSS, Weiss RR, Oba E, Kozicki LE, Souza FA, Bergstein-Galan TG, Muehlbauer E, Silvestri M, de Lima PHL, Vaz ES.In equine reproduction, determining foetal sex is of economic and strategic importance, but currently available methods are often invasive, costly, or require specialised expertise. This study aimed to assess whether plasma progesterone concentrations could serve as a predictive tool for foetal sex determination in Criollo mares between the 4th and 8th months of gestation and to determine whether these measurements could identify foetal sex. Blood samples were collected at 30-day intervals from 17 Crioula mares between 114 days and 240 days of gestation. Maternal plasma progesterone concen...
Newcombe JR, Claes AN, Cuervo-Arango J.Early embryonic loss (EEL), particularly between Days 14 and 42 of pregnancy, remains a key concern in equine reproduction. This study investigates the incidence of spontaneous luteolysis-used here as a marker of maternal recognition of pregnancy (MRP) failure-in both pregnant Thoroughbred (TB) broodmares and recipient mares carrying either in vivo-derived (IVD) or in vitro-produced (IVP) embryos. Retrospective reproductive data from 2078 pregnancies in TB and 532 pregnancies in recipients were analysed to determine the incidence and characteristics of clinical luteolysis during pregnancy. Ove...
Samsel J, Gündemir O, Szara T, Witkowski M.Uterine torsion in mares belongs to maternal pregnancy disorders, accounting for 5-10% of complications in the last trimester of pregnancy. Two surgical techniques for repositioning uterine torsion are used: flank laparotomy in local anesthesia on a standing mare (SFL) and midline laparotomy carried out under general anesthesia (MI). The study aims to present the exact protocol used by the authors to qualify a mare with uterine torsion for surgery using one of the above-mentioned methods.A total of 19 mares were operated on, of which 13 underwent midline laparotomy under general anesthesia, an...
Galli C, Lagutina I, Crotti G, Colleoni S, Turini P, Ponderato N, Duchi R, Lazzari G.Several animal species, including sheep, mice, cattle, goats, rabbits, cats, pigs and, more recently, mules have been reproduced by somatic cell cloning, with the offspring being a genetic copy of the animal donor of the nuclear material used for transfer into an enucleated oocyte. Here we use this technology to clone an adult horse and show that it is possible to establish a viable, full-term pregnancy in which the surrogate mother is also the nuclear donor. The cloned offspring is therefore genetically identical to the mare who carried it, challenging the idea that maternal immunological rec...
Hahn S, Giaglis S, Hoesli I, Hasler P.The intention of this review is to provide an overview of the potential role of neutrophil extracellular traps (NETs) in mammalian reproduction. Neutrophil NETs appear to be involved in various stages of the reproductive cycle, starting with fertility and possibly ending with fetal loss. The first suggestion that NETs may play a role in pregnancy-related disorders was in preeclampsia, where vast numbers were detected in the intervillous space of affected placentae. The induction of NETosis involved an auto-inflammatory component, mediated by the increased release of placental micro-debris in p...
Frank N, Tadros EM.Abnormalities of insulin metabolism include hyperinsulinaemia and insulin resistance, and these problems are collectively referred to as insulin dysregulation in this review. Insulin dysregulation is a key component of equine metabolic syndrome: a collection of endocrine and metabolic abnormalities associated with the development of laminitis in horses, ponies and donkeys. Insulin dysregulation can also accompany prematurity and systemic illness in foals. Causes of insulin resistance are discussed, including pathological conditions of obesity, systemic inflammation and pituitary pars intermedi...
Katila T.This review attempts to summarize the current knowledge on uterine inflammatory response after mating in horses, pigs and cattle. Post-mating endometritis has been extensively studied in horses as it has been considered to cause infertility. The inflammation is known to occur also in cattle, but it has not been investigated to a similar extent. There are a number of publications about mechanisms of post-mating uterine inflammation in pigs, which seem to resemble those in horses. The major focus of this review is the horse, but relevant literature is presented also on swine and cattle. Spermato...
Riddle WT, LeBlanc MM, Stromberg AJ.Endometrial cytology and culture specimens (n=2123) were collected concurrently with a guarded uterine culture instrument from 970 mares (738 barren, 1230 foaling and 155 maiden mares) during three breeding seasons (2001-2004). Results were compared to the 28-d pregnancy rate for the cycle from which the samples were taken. Cytological smears were evaluated for inflammation at x100 and graded as: not inflammatory (0-2 neutrophils/field), moderate inflammation (2-5 neutrophils/field), severe inflammation (>5 neutrophils/field), or hypocellular (scant epithelial cells and no neutrophils). Ute...
Weems CW, Weems YS, Randel RD.Prostaglandins impact on ovarian, uterine, placental, and pituitary function to regulate reproduction in female livestock. They play important roles in ovulation, luteal function, maternal recognition of pregnancy, implantation, maintenance of gestation, microbial-induced abortion, parturition, postpartum uterine and ovarian infections, and resumption of postpartum ovarian cyclicity. Prostaglandins have both positive and negative effects on reproduction; they are used to synchronize oestrus, terminate pseudopregnancy in mares, induce parturition, and treat retained placenta, luteinized cysts, ...
Murphy BD, Martinuk SD.Cells from the chorionic girdle of the equine trophoblast invade the maternal endometrium at day 36 of gestation and become established as secretory elements known as the endometrial cups. These structures, which persist for 40-60 days, produce a gonadotropin which can be found in circulation until about day 130 of gestation. This glycoprotein has been identified in the horse and the donkey, with the former having received much better characterization. It consists of 2 noncovalently linked peptide chains; an alpha-subunit of 96 amino acids, which is common to that found in other horse glycopro...
Rekant SI, Lyons MA, Pacheco JM, Arzt J, Rodriguez LL.Abnormal body temperature is a major indicator of disease; infrared thermography (IRT) can assess changes in body surface temperature quickly and remotely. This technology can be applied to a myriad of diseases of various etiologies across a wide range of host species in veterinary medicine. It is used to monitor the physiologic status of individual animals, such as measuring feed efficiency or diagnosing pregnancy. Infrared thermography has applications in the assessment of animal welfare, and has been used to detect soring in horses and monitor stress responses. This review addresses the var...
Klein C, Scoggin KE, Ealy AD, Troedsson MH.Establishment and maintenance of pregnancy are critically dependent on embryo-maternal communication during the preimplantation period. To gain new insights into this complex process in the horse, transcriptional profiling of Day 13.5 pregnant and cyclic endometrial tissue samples was carried out using custom-designed microarrays. Selected array data were validated using quantitative RT-PCR, and proteins of interest were localized using immunohistochemistry. One hundred and six transcripts were up-regulated, whereas 47 transcripts showed lower expression levels in pregnant mares, that is, were...
da Silveira JC, Winger QA, Bouma GJ, Carnevale EM.Age-related decline in fertility is a consequence of low oocyte number and/or low oocyte competence resulting in pregnancy failure. Transforming growth factor (TGF)-β signalling is a well-studied pathway involved in follicular development and ovulation. Recently, small non-coding RNAs, namely microRNAs (miRNAs), have been demonstrated to regulate several members of this pathway; miRNAs are secreted inside small cell-secreted vesicles called exosomes. The overall goal of the present study was to determine whether altered exosome miRNA content in follicular fluid from old mares is associated wi...
Morris LH, Allen WR.The findings of a retrospective survey of 1393 Thoroughbred mares visiting 22 studfarms in the Newmarket region of the UK during the 1998 mating season were compared with those of a similar study undertaken in 1983. The effects of mare age and status, stallion, month of mating, application of uterine treatments and other parameters on the rates of singleton and twin conception and subsequent pregnancy losses were analysed. Mare age and status significantly affected the per cycle pregnancy rate and the incidence of pregnancy loss. Overall, the mean number of matings per oestrus was 1.12 and the...
Allsopp MT, Lewis BD, Penzhorn BL.The intra-erythrocytic parasite Theileria equi is one of two tick-transmitted causative agents of equine piroplasmosis. Piroplasms of T. equi can be transmitted across the equine placenta and once a horse is infected, it appears to remain a lifelong carrier, since anti-theilerial drugs suppress but do not eliminate the parasite. Carrier mares may transmit the organism to their offspring and this may result in abortion or neonatal piroplasmosis, but observations by some researchers suggest that foals may be born as carriers yet remain apparently healthy. Using a T. equi-specific oligonucleotide...
Nagel C, Aurich C, Aurich J.This review summarizes current knowledge on stress-like responses in parturient animals and their role for the onset and fine-tuning of parturition. The antepartum maternal cortisol increase is part of the endocrine changes that initiate parturition but a further increase in cortisol release during labor indicates a stress response. During the last minutes of delivery, sinus arrhythmias occur in 80% of foaling mares and 60% of calving cows. Expulsion of the neonate is thus characterized by parasympathetic dominance. In late-pregnant cows transported by road, cortisol concentrations increased b...
Love CC.Sperm quality has an important role in determining fertility. Although there have been numerous studies to document the relationship between sperm quality and fertility, the methods of determining this association and conclusions vary. In the present study, computer-assisted sperm analysis (CASA) was used for evaluation of sperm motility, and differential interference contrast (DIC) microscopy was used for evaluating sperm morphologic features of breeding stallions. Fertility was measured using three endpoints: seasonal pregnancy rate (PR), percent pregnant/cycle (PC), and percent pregnant/fir...
Leemans B, Gadella BM, Stout TA, De Schauwer C, Nelis H, Hoogewijs M, Van Soom A.In contrast to man and many other mammalian species, conventional in vitro fertilization (IVF) with horse gametes is not reliably successful. The apparent inability of stallion spermatozoa to penetrate the zona pellucida in vitro is most likely due to incomplete activation of spermatozoa (capacitation) because of inadequate capacitating or fertilizing media. In vivo, the oviduct and its secretions provide a microenvironment that does reliably support and regulate interaction between the gametes. This review focuses on equine sperm-oviduct interaction. Equine sperm-oviduct binding appears to be...
Pomar FJ, Teerds KJ, Kidson A, Colenbrander B, Tharasanit T, Aguilar B, Roelen BA.The occurrence of pregnancies and births after embryo transfer (ET) of in vivo produced embryos is generally more successful compared to that of embryos produced in vitro. This difference in ET success has been observed when embryos of morphological equal (high) quality were used. The incidence of apoptosis has been suggested as an additional criterion to morphological embryo evaluation in order to assess embryo quality and effectively predict embryo viability. In this study, equine, porcine, ovine, caprine and bovine in vivo and in vitro produced morphologically selected high quality (grade-I...
Merkl M, Ulbrich SE, Otzdorff C, Herbach N, Wanke R, Wolf E, Handler J, Bauersachs S.Establishment and maintenance of pregnancy in equids is only partially understood. To provide new insights into early events of this process, we performed a systematic analysis of transcriptome changes in the endometrium at Days 8 and 12 of pregnancy. Endometrial biopsy samples from pregnant and nonpregnant stages were taken from the same mares. Composition of the collected biopsy samples was analyzed using quantitative stereological techniques to determine proportions of surface and glandular epithelium and blood vessels. Microarray analysis did not reveal detectable changes in gene expressio...
Colenbrander B, Gadella BM, Stout TA.Pregnancy rates in managed horse populations depend on the innate fertility of the mares and stallions involved and on the quality of breeding management. Of course, because a single stallion usually mates many mares, stallion fertility is a critical factor in the overall success of a breeding program. Unfortunately, accurate evaluation of stallion fertility per se requires a large number of normal mares to be mated and is necessarily retrospective. Rather, the ideal is to predict fertility in advance of the stallion's breeding career, and this is currently attempted by way of a thorough physi...
Morein B, Blomqvist G, Hu K.The maintenance of pregnancy requires suppression of the maternal immune system which would naturally recognize the developing fetus as an allograft and seek to destroy it by mounting a Th1 regulated cytotoxic immune response. During pregnancy a range of soluble factors are produced by the placenta which switch maternal immune regulation towards a protective Th2 phenotype. These factors also influence the developing fetal immune system and all newborns initially have an immunological milieu skewed towards Th2 immunity. Vaccination during the neonatal period must therefore overcome the dual cha...
Edington N, Smyth B, Griffiths L.One of three mares in the last trimester of pregnancy became paraplegic 7 days after experimental infection with EHV-1 and was killed 10 days after infection (d.p.i.). The other two mares aborted foetuses at 12 and 14 d.p.i. In the first mare, virus was detected by immunofluorescence (IIF) and immunoperoxidase (IP) staining in endothelial cells of the endometrium, placenta and umbilical vein, but not in any other foetal tissues. In the experimentally aborted foetuses, and in two other independent field cases of abortions, endothelial cell infection was also detected in the foetuses, both in ma...
Choi YH, Varner DD, Love CC, Hartman DL, Hinrichs K.Work with lyophilized sperm helps delineate the factors required for successful fertilization. We investigated the use of lyophilized sperm in equine embryo production. In Experiment 1, sperm DNA fragmentation index was not affected by three freeze/thaw or lyophilization cycles. In Experiment 2, oocytes injected with lyophilized sperm or with sperm from a treatment in which lyophilized sperm were suspended in sperm cytoplasmic extract (SE) yielded blastocyst development rates of 0 and 28% respectively (P < 0.05). In Experiment 3, blastocyst development rate was 6-11% after injection of sper...
Mahé C, Zlotkowska AM, Reynaud K, Tsikis G, Mermillod P, Druart X, Schoen J, Saint-Dizier M.In vitro fertilization (IVF) gives rise to embryos in a number of mammalian species and is currently widely used for assisted reproduction in humans and for genetic purposes in cattle. However, the rate of polyspermy is generally higher in vitro than in vivo and IVF remains ineffective in some domestic species like pigs and horses, highlighting the importance of the female reproductive tract for gamete quality and fertilization. In this review, the way the female environment modulates sperm selective migration, survival, and acquisition of fertilizing ability in the oviduct is being considered...
Canisso IF, Panzani D, Miró J, Ellerbrock RE.Donkeys are nonseasonal, polyestrous, territorial, and nonharem breeders. Although there are many similarities between horses and donkeys, there are also reproductive features that differ, from the longer cervix in the jenny to spermatogenic efficiency in the jack. Mules display reproductive cyclic activity but are rarely fertile. Frozen donkey semen has high pregnancy rates in mares, but lower rates in jennies. This article reviews key aspects of donkey and mule reproductive physiology, reproductive medicine, and assisted reproductive techniques that are useful for practitioners offering assi...
Galli C, Colleoni S, Duchi R, Lagutina I, Lazzari G.Development of assisted reproductive technologies in horses has been relatively slow compared to other domestic species, namely ruminants and pigs. The scarce availability of abattoir ovaries and the lack of interest from horse breeders and breed associations have been the main reasons for this delay. Progressively though, the technology of oocyte maturation in vitro has been established followed by the application of ICSI to achieve fertilization in vitro. Embryo culture was initially performed in vivo, in the mare oviduct or in the surrogate sheep oviduct, to achieve the highest embryo devel...
Moore T, Williams JM, Becerra-Rodriguez MA, Dunne M, Kammerer R, Dveksler G.Pregnancy-specific glycoproteins (PSGs) are members of the immunoglobulin superfamily and are closely related to the predominantly membrane-bound CEACAM proteins. PSGs are produced by placental trophoblasts and secreted into the maternal bloodstream at high levels where they may regulate maternal immune and vascular functions through receptor binding and modulation of cytokine and chemokine expression and activity. PSGs may have autocrine and paracrine functions in the placental bed, and PSGs can activate soluble and extracellular matrix bound TGF-β, with potentially diverse effects on multip...
Allen WR, Brown L, Wright M, Wilsher S.Previous surveys of reproductive efficiency in British Thoroughbreds included only mares and stallions standing on studfarms in and around Newmarket. The present study was widened to compare Flatrace (FR) (Group A) and National Hunt (NH) (Group B) mares and stallions on studfarms throughout England. Objective: To assess the influences of mare type, status and age, and veterinary manipulations on reproductive efficiency parameters. To compare the inherent fertility of stallions, based on singleton and twin pregnancy rates and pregnancy loss rates, in Groups A and B Thoroughbred breeding stock. ...
Betteridge KJ, Eaglesome MD, Mitchell D, Flood PF, Beriault R.Forty nine embryos, twenty unfertilized eggs and five other fresh eggs of 'doubtful' status have been recovered from 58 pony mares in 122 flushes up to 22 days after ovulation. The fresh egg or embryo recovery rate was 78% with surgical methods (or at slaughter) and 40-60% with non-surgical methods of recovery. The fertilization rate was about 70%. It has been confirmed that horse embryos normally enter the uterus as blastocysts 5-6 days after ovulation. Three features of early embryo morphology have become clearer upon comparison with unfertilized eggs of similar ages; early embryos are often...
Galli C, Crotti G, Notari C, Turini P, Duchi R, Lazzari G.Embryo production by in vitro techniques has increased steadily over the years. For cattle where this technology is more advanced and is applied more, the number of in vitro produced embryos transferred to final recipients was over 30,000 in 1998. An increasing proportion of in vitro produced embryos are coming from oocytes collected from live donors by ultrasound-guided follicular aspiration (ovum pick up, OPU). This procedure allows the repeated production of embryos from live donors of particular value and is a serious alternative to superovulation. Ovum pick up is a very flexible technique...
Allen WR, Stewart F.A tough, elastic glycoprotein capsule envelops the equine blastocyst between Days 6 and 23 after ovulation. It maintains the spherical configuration of, and provides physical support for, the embryo as it traverses the entire uterine lumen during Days 6-17, propelled by myometrial contractions that are stimulated by pulsatile release of prostaglandin F2alpha and prostaglandin E2. The capsule also accumulates constituents of the exocrine secretions of the endometrial glands ('uterine milk') as nutrients for the mobile embryo as it releases its antiluteolytic maternal recognition-of-pregnancy si...
Smits K, Willems S, Van Steendam K, Van De Velde M, De Lange V, Ververs C, Roels K, Govaere J, Van Nieuwerburgh F, Peelman L, Deforce D, Van Soom A.During maternal recognition of pregnancy (MRP), a conceptus-derived signal leads to the persistence of the corpus luteum and the maintenance of gestation. In the horse, the nature of this signal remains to be elucidated. Several studies have focused on the changes in gene expression during MRP, but little information exists at the protein level. The aim of this study was to identify the proteins at the embryo-maternal interface around signalling of MRP in the horse (day 13) by means of mass spectrometry. A distinct influence of pregnancy was established, with 119 proteins differentially expres...
