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.
Wilsher S, Allen WR.Eight day 10 horse embryos were transferred non-surgically to recipient mares that had ovulated 7 days after the donors. The embryonic vesicle was seen ultrasonographically in all eight recipients, and three out of eight (38%) of the vesicles developed an embryo proper with a beating heart. Conceptus expansion was initially slower than that in control mares but continued until day 22 (recipient day 15). Time of fixation of the vesicle was related to its diameter, rather than uterine stage. Although the embryo proper first appeared ultrasonographically on day 22, as normal, it grew more slowly ...
Cochet M, Vaiman D, Lefèvre F.Interferons (IFNs) are cytokines of vertebrates with many biological effects including antiviral, immunoregulatory and antiproliferative activities. Among them, mammalian type I IFNs represents a large family of related proteins, mainly virus-inducible, divided in 10 distinct subfamilies named alpha, beta, omega, delta, epsilon, alphaomega, nu, tau, kappa and zeta (or Limitin). Some type I IFN subfamilies are physiologically expressed by the conceptus during early pregnancy in ungulates. This is the case in ruminants with IFN-tau (which triggers the maintenance of the maternal corpus luteum du...
Manso Filho HC, McKeever KH, Gordon ME, Costa HE, Lagakos WS, Watford M.Glutamine is the most abundant free alpha-AA in the mammalian body, and large amounts of glutamine are extracted by both the fetus during pregnancy and the mammary gland during lactation. The work presented here addressed the hypothesis that there would be major changes in glutamine metabolism in the mare during the transition period, the time between late gestation, parturition, and early lactation. Eight foals were born to Standardbred mares provided with energy and protein at 10% above NRC recommendations, and foals remained with mares for 6 mo. During lactation, lean body mass decreased by...
Govaere J, Hoogewijs M, De Schauwer C, Van Zeveren A, Smits K, Cornillie P, de Kruif A.Naturally occurring monozygotic twins are extremely rare in the horse. This paper describes an abortion in a mare after 260 days of pregnancy with monozygotic twins, one a fresh foal and the other a mummified foal.
Raz T, Gray A, Hunter B, Card C.Superovulatory treatment may potentially increase the embryo recovery rate and the per-cycle pregnancy rate in normal or subfertile mares that are managed properly. However, some studies suggest a possible negative effect of superovulatory treatment on ovarian follicular maturation and embryo viability. Objectives of the present study were to investigate the early effects of eFSH treatment in reproductively normal mares in terms of: folliculogenesis, pregnancy rate, early embryonic development, reproductive tract parameters (tone and edema), and serum estradiol-17beta and progesterone concentr...
Coffman EA, Abd-Eldaim M, Craig LE.A pregnant 18-year-old Quarterhorse mare presented with fever, anorexia, tachycardia, tachypnea, and gastrointestinal hypermotility at day 68 of gestation. Potomac horse fever was diagnosed based on polymerase chain reaction (PCR) analysis of whole blood and a high antibody titer to Neorickettsia risticii. The mare made a rapid clinical recovery following antibiotic therapy, but aborted 98 days later. Necropsy on the aborted fetus revealed lymphohistiocytic colitis, lymphadenitis, myocarditis, and hepatitis. The placenta was grossly and histologically normal. Formalin-fixed lymph node, thymus,...
Elliott C, Morton J, Chopin J.Foaling data from 348 Thoroughbred foals born on a commercial stud were analysed to investigate interrelationships among mare age, parity, gestation length, foal sex, placental weight, and foal birth weight. Placental weight was positively correlated with foal birth weight up to a threshold of 6.5 kg; above this, placental weight was not significantly associated with foal birth weight. Placental weight was assessed, including the amniotic membranes and umbilical cord as well as the allantochorion. Using path analysis, parity was positively associated with foal birth weight both directly and th...
Carstanjen B, Schönert S, Heblinski N, Gruber AD.Fibroleiomyomas of the ovary are rare. This smooth muscle tumour may develop and increase in size during pregnancy. Diagnosis is based on histological and immunohistochemical analyses. Histologically, the ovarian fibroleiomyoma consists of non-invasive bundles of smooth muscle cells that synthesize collagen-like extracellular matrix. This case report describes an ovarian fibroleiomyoma in a pregnant multiparous broodmare with a history of intermittent signs of colic.
de Mestre AM, Miller D, Roberson MS, Liford J, Chizmar LC, McLaughlin KE, Antczak DF.The objective of this study was to identify transcription factors associated with differentiation of the chorionic girdle, the invasive form of equine trophoblast. The expression patterns of five transcription factors were determined on a panel of conceptus tissues from early horse pregnancy. Tissues from Days 15 through 46 were tested. Eomesodermin (EOMES), glial cells missing homologue 1 (GCM1), heart and neural crest derivatives expressed transcript 1 (HAND1), caudal type homeobox 2 (CDX2), and distal-less homeobox 3 (DLX3) were detected in horse trophoblast, but the expression patterns for...
Lezica FP, Filip R, Gorzalczany S, Ferraro G, de Erausquin GA, Rivas C, Ladaga GJ.In the present study, we determined the incidence and effects of season and weather on clinical manifestations of endophyte-infected ryegrass toxicity, performed chemical detection and pharmacological bioassays on ryegrass extracts, and conducted trials on: (i) effects of domperidone or metochlopramide on ovarian inactivity induced by endophyte-infected ryegrass; (ii) efficacy of buspirone or dihydrochloro phenyl piperazine (m-CPP) for preventing suppressed milk production induced by endophyte-infected ryegrass; and (iii) efficacy of domperidone to induce ovulation during winter anestrus. Mare...
Blanco ID, Devito LG, Ferreira HN, Araujo GH, Fernandes CB, Alvarenga MA, Landim-Alvarenga FC.This study examined the effect of treating mares with equine pituitary extract (EPE) alone or in combination with hCG on the recovery rate of immature follicles by transvaginal follicular aspiration (ovum pick-up; OPU). Ten normally cycling crossbred mares aged 3-15 years and weighing 350-400 kg were subjected to each of three treatments in a random sequence with each exposure to a new treatment separated by a rest cycle during which a spontaneous ovulation occurred. The treatments were (1) superovulated with 25mg EPE and treated with 2500 IU hCG, (2) superovulation with 25mg EPE, and (3) cont...
Campos-Chillòn LF, Suh TK, Barcelo-Fimbres M, Seidel GE, Carnevale EM.The objectives of this study were to: (1) determine an optimal method and stage of development for vitrification of bovine zygotes or early embryos; and (2) use the optimal procedure for bovine embryos to establish equine pregnancies after vitrification and warming of early embryos. Initially, bovine embryos produced by in-vitro fertilization (IVF) were frozen and vitrified in 0.25mL straws with minimal success. A subsequent experiment was done using two vitrification methods and super open pulled straws (OPS) with 1- or 8-cell bovine embryos. In Method 1 (EG-O), embryos were exposed to 1.5M e...
Abd-Elnaeim MM, Derar IR, Wilsher S, Allen WR, Leiser R, Schuler G.The functions of placental oestrogens during equine pregnancy are still unclear. Yet, they may act predominantly as local regulators of growth and differentiation in the microplacentomes. Thus, expression patterns of oestrogen receptors (ERs) alpha and beta were investigated in the microcotyledonary placenta from pregnant mares at 110, 121, 179, 199 and 309 days of gestation by immunohistochemistry. In microplacentomes, both the ER isoforms were detected in trophoblast (T) cells, chorionic villous stroma (FS), microcaruncular epithelium (ME) and microcaruncular stroma (MS). Proportions of posi...
Bemis DA, Bryant MJ, Kania SA, Newman SJ.Based on the scarcity of reports in veterinary medicine literature, it appears that Arcanobacterium spp. are rarely isolated from horses. Recently, a single isolate from vaginal discharge in a mare was characterized as a new species, Arcanobacterium hippocoleae. The present report describes a case of necrosuppurative placentitis and stillbirth in an American Quarterhorse mare. Numerous colonies of irregular, Gram-positive, rod-shaped bacteria were observed by histological examination within fibrin lattice associated with placental lesions. Arcanobacterium hippocoleae was isolated in large numb...
Carter AM.Recently a fossil of one of the earliest jawed fishes was found with a fetal skeleton and the remains of a cord. It was from the Devonian period and takes the history of vertebrate placentation back to 380 million years ago. This and later fossil evidence for viviparity in marine reptiles and early mammals is reviewed. Of particular interest are the fossils of horses as they document that a reproductive strategy with a single precocial newborn was evolved early on. In one instance there is sufficient representation of soft tissue to imply that early horses had a diffuse placenta, much as had b...
Manso Filho HC, Costa HE, Wu G, McKeever KH, Watford M.In most mammalian species the developing fetus utilizes large amounts of glutamine derived both from the maternal circulation and synthesized de novo in the placenta. The present study was designed to determine the role of the placenta in glutamine synthesis in the horse. The placentae from eight Standardbred mares were sampled immediately after parturition together with additional tissues obtained at necropsy from three Standbred mares during diestrous. Glutamine synthetase protein was detectable in the non-pregnant horn of the placenta in amounts similar to those seen in gluteus muscle, but ...
Fowden AL, Forhead AJ, Ousey JC.Delivery of viable young requires co-ordination of fetal maturation with the onset of labour at term. In turn, this depends on a cascade of fetal and maternal endocrine events. The sequence of these events is broadly similar in most mammals but there are differences in placental hormone synthesis and in the timing and magnitude of key prepartum endocrine changes between species. In most farm animals, maternal progesterone (P4) levels decline and oestrogen levels increase in the last 5 - 10 days before delivery in response to activation of the fetal hypothalamicpituitary-adrenal (HPA) axis and ...
Kruger K, Saulez MN, Neser JA, Solberg K.Lead (Pb) intoxication in horses is usually a chronic phenomenon with clinical signs associated with central nervous dysfunction. This report gives details of a case of acute Pb intoxication in a 9-year-old American Saddlebred mare with severe, progressive and ultimately fatal neurological deterioration. During the 4 days of hospitalisation, clinical signs progressed from intermittent headshaking and depression to severe, continuous, uncontrollable manic behaviour. At autopsy, three grey-coloured, hard metal particles were present in the gastrointestinal tract and subsequently found to contain...
Janowski T, Skolimowska A, Zdunczyk S, Baranski W.Total of 30 pregnant mares were used in this study: 17 Thoroughbred and 13 Primitive Polish Horse. The concentration of total unconjugated oestrogens was determined by radioimmunoassay in faecal samples obtained every second week after mating until delivery or interruption of pregnancy. Concentration of oestrogens in pregnant healthy mares ranged from 40 to 200 ng/g and showed typical profiles for pregnancy. In 5 of 30 mares (16.6%) of either breed abortions and cases of embryonic death occurred. Abortions were preceded by sharp or gradual decrease in oestrogen concentration, whereas prior to ...
Annandale CH, Schulman ML, Kirkpatrick RD.Twelve pony mares were randomly assigned to either a control or a treatment group and inseminated with fresh, raw semen from a single stallion of known fertility in a cross-over trial design. Pregnancy was diagnosed by transrectal ultrasound 12-14 days post-ovulation and then terminated by administration of a luteolytic dose of cloprostenol. Treatment mares received a uterine instillation of 100 ml of electrochemically activated (ECA) saline 4-12 hours post-insemination. Control mares received no treatment post-insemination. Per cycle pregnancy rate was 58.3 % in the control group and 50 % in ...
Szeredi L, Jánosi S, Tenk M.Klebsiella (K.) oxytoca infection induced the abortion of a female equine fetus in the 10th month of pregnancy. Bacteria were cultured from the liver, lung and stomach content. They were labelled with an anti-Mycobacterium bovis antibody in the thymus, liver and lungs and were stained with Giemsa and Brown-Brenn staining in the thymus and lung. The diffusely consolidated lungs contained numerous grey-whitish foci 2-4 mm in diameter, which corresponded to severe pyogranulomatous pneumonia characterised by numerous intraalveolar neutrophils and macrophages and multinucleated Langhans' giant cell...
Araujo GH, Rocha Filho AN, Lopes EP, Moya CF, Alvarenga MA.The effects of a low dose of equine purified FSH (eFSH) on incidence of multiple ovulations and embryo recovery rate in mares were studied. During the physiological breeding season in Brazil (19 degrees 45'45'S), 14 Mangalarga Marchador donor mares were used in a crossover study and another 25 mares of the same breed, between 3 years and 12 years of age were used as recipients for the embryo transfers. Donors were monitored during two consecutive oestrus cycles, an untreated control cycle followed by a treated cycle, when eFSH was administered. In both cycles, after an embryo collection attemp...
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...
Hayes MA, Quinn BA, Keirstead ND, Katavolos P, Waelchli RO, Betteridge KJ.A critical period of early gestation in the mare involves the immobilization (fixation) of the encapsulated conceptus at around days 16-17. We compared the major proteins in the normal equine embryonic capsule and endometrial secretions around the period of fixation with those from pregnancies in the process of termination induced by administration of an analogue of prostaglandin F(2 alpha) (PGF(2 alpha)). Uterocalin and beta(2)-microglobulin (beta(2)M) associated with the embryonic capsule were proteolytically converted to smaller forms during the fixation period. These conversions were simil...
Donadeu FX, Pedersen HG.The mare provides a unique experimental model for studying follicle development in monovular species. Development of antral follicles in horses is characterized by the periodic growth of follicular waves which often involve the selection of a single dominant follicle. If properly stimulated, the dominant follicle will complete development and eventually ovulate a fertile oocyte. Regulation of follicular wave emergence and follicle selection involves an interplay between circulating gonadotropins and follicular factors that ensures that individual follicles are properly stimulated to grow (or t...
Bucca S, Carli A, Buckley T, Dolci G, Fogarty U.The present study describes the effect of a single dose of dexamethasone administered to mares at time of breeding. In an initial experiment, the authors investigated safety of treatment. In a second experiment the effect of treatment on the uterine environment, fetal development and pregnancy outcome was examined. In the final part of the study, mares susceptible to persistent mating induced endometritis were identified, by means of a risk factor score system and the effect of treatment evaluated. Results indicated that dexamethasone administered at breeding time did not negatively impact on ...
Jung C, Hospes R, Bostedt H, Litzke LF.To report on the outcome of surgical treatment of uterine torsion in preterm mares. Methods: Retrospective case series of pregnant mares with uterine torsion presented to the Clinic for Obstetrics, Gynaecology and Andrology of Large and Small Animals. Methods: Hospital records of all pregnant mares that underwent ventral midline laparotomy for uterine torsion between 1998 and 2004 were reviewed. The signalment, history, clinical signs, results of diagnostic procedures, direction and degree of the uterine twist, treatment and outcome were retrieved from each case record. Results: This study com...
Miller CD.This manuscript is a review of current protocols, advantages, and disadvantages of breeding mares with frozen-thawed equine semen. Issues affecting pregnancy rates are discussed, including proper mare selection, induction of ovulation, insemination dose, timing of insemination (single-dose versus multiple-dose insemination), methods of insemination (transrectal-guided deep-horn versus hysteroscopic insemination), and post-insemination mare management procedures. In a retrospective analysis of breeding records, a single-dose of frozen-thawed semen was inseminated within 6h post-ovulation; the p...
Ellenberger C, Wilsher S, Allen WR, Hoffmann C, Kölling M, Bazer FW, Klug J, Schoon D, Schoon HA.Previous studies have shown that the equine uterus produces many progesterone-dependent proteins throughout gestation. In particular, uterocalin and uteroferrin are detectable using electrophoresis or blot analyses but information regarding the immunohistochemical placental distribution of these two proteins is rare and information regarding uteroglobin is still lacking. The aim of the present study was to co-immunolocalise these three secretory proteins in the mare's uterus throughout gestation in an effort to understand their functional role in the maintenance of pregnancy. Therefore, endome...
Ferreira JC, Canesin HS, Ignácio FS, Rocha NS, Pinto CR, Meira C.The present experiment was divided into three studies to investigate the effect of age and endometrial degeneration on uterine blood flow of mares. In study 1, the influence of semen infusion and conception was evaluated using noninseminated (non-AI), inseminated nonpregnant (AI-NP), and inseminated pregnant (AI-P) mares (n = 7 mares/group). In study 2, the effect of age was investigated using young (≤6 years), adult (from 8 to 12 years), and old (≥15 years) pregnant mares (n = 7 mares/group). In study 3, uterine blood flow was also characterized in pregnant mares (n = 7 mares/group) with ...
Silver M, Barnes RJ, Comline RS, Fowden AL, Clover L, Mitchell MD.The concentrations of the primary prostaglandins (PG) F-2alpha and E-2 and the metabolite 13,14-dihydro-15-oxo-prostaglandin (PGFM) in maternal and fetal plasma and in allantoic fluid were measured in chronically catheterized mares and fetuses. A gradual rise in all 3 PGs occurred with increasing gestational age. PGE-2 and PGF-2 alpha levels were highest in the allantoic fluid and lowest in the maternal plasma, whereas PGFM concentrations were greatest in maternal plasma. Significant venous-arterial plasma differences in PGFM concentration were detected across the uterine circulation between 1...
Ousey JC, Dudan F, Rossdale PD.The status of the mare and foetus in relation to readiness for birth was assessed by measurement of the electrolytes sodium, potassium and calcium in mammary secretions pre-partum. Sixteen Thoroughbred mares were allowed to foal spontaneously and the ionic status of their mammary secretions was measured over three to five weeks pre-partum. From these measurements, a scoring system was developed where an ionic score of 35 points or more suggested that the mare was within 24 h of foaling. On the basis of this ionic score, 10 pony mares were induced with either oxytocin or fluprostenol and assess...
Holcombe SJ, Embertson RM, Kurtz KA, Roessner HA, Wismer SE, Geor RJ, Kaneene JB.Increased serum nonesterified fatty acids (NEFA) and decreased serum electrolytes are linked to abdomasal displacements in post partum dairy cattle. Post partum colic in mares may be associated with metabolic changes specific to pregnancy and the periparturient period. Objective: To determine if fluctuations in serum NEFA, ionised calcium (iCa) and magnesium (iMg) occurred in periparturient mares and if these alterations were associated with post partum colic. Methods: Longitudinal observational study. Methods: Mares from 3 farms in central Kentucky were enrolled. Blood samples were collected ...
Winsco KN, Coverdale JA, Wickersham TA, Lucia JL, Hammer CJ.Thirty pregnant mares (538 to 695 kg BW; 4 to 19 yr of age) were used to evaluate the effects of plane of nutrition on DMI of hay and mare performance (BW, BCS, and rump fat) during the last third of pregnancy. Mares were divided into 4 blocks by their expected foaling date and randomly assigned within block to either a hay or concentrate plus hay diet (concentrate fed at 0.75% BW, as-fed basis) with 15 mares per treatment. Treatments began 110 d before expected foaling date (230 d of gestation) and terminated at parturition. Mares were housed by block and allowed ad libitum access to coastal ...
Bartoš L, Bartošová J, Pluháček J.In a previous study, we suggested that the common practice of transporting a mare for mating and then bringing her back to an environment that also contains males that did not sire the fetus may be a major cause of high percentages of pregnancy disruption in domestic horses. In this study, we tested whether disruption of pregnancies induced by AI occurs as frequently as after mating with a strange stallion away from home and is affected by the same factors in the home social environment. Based on 77 records, the probability of pregnancy disruption after AI depended on the social environment in...
Kelly CM, Hoyer PB, Wise ME.Dispersed horse luteal cells were used to evaluate the ability of horse LH, hCG and PMSG to stimulate progesterone secretion in vitro. Morphological characterization of these cells before gonadotrophin stimulation indicated the presence of two populations of cells based on cell diameters. In luteal cells incubated as suspended cells, horse LH and hCG stimulated (P less than or equal to 0.05) progesterone production at all levels of treatment. Stimulation of progesterone secretion by hCG was greater (P less than or equal to 0.05) than by horse LH over the range of concentrations utilized. When ...
Hollinshead FK, Mehegan MK, Gunn A, Nett T, Bruemmer JE, Hanlon DW.The aim of this project was to test the hypothesis that progesterone concentration 5 days after ovulation did not differ between pregnant and nonpregnant Thoroughbred mares on stud farms located in the Waikato region of New Zealand. A prospective cohort study was performed involving five stud farms in the Waikato region of New Zealand during the 2018 breeding season. A total of 275 mares were enrolled in the study. Mares were served by 34 individual stallions. Blood samples were taken from each mare 5 days after ovulation (D0) and measured for progesterone concentration. Early pregnancy was co...
Bigler NA, Gross JJ, Baumrucker CR, Bruckmaier RM.This review discusses endocrine and functional changes during the transition from late gestation to lactation that are related to the production of colostrum in different mammalian species. Species covered in this article include ungulate species (cattle, sheep, goats, pigs, horses), rodents (rat, mouse), rabbits, and carnivores (cats, dogs), as well as humans. An immediate availability of high quality colostrum for the newborn after birth is crucial in species where a transfer of immunoglobulins (Ig) does not or only partially occur via the placenta during pregnancy. Declining activity of ges...
Bartošová J, Komárková M, Dubcová J, Bartoš L, Pluháček J.Lactation is the most energy demanding part of parental care in mammals, so parent-offspring conflict arises over milk provided by the mother. In some species females commonly become pregnant shortly after parturition of previous young. This further intensifies mother-offspring conflict due to concurrent pregnancy and lactation. In equids it has been well established that pregnant females wean their foals earlier than non-pregnant ones. Intensified mother-offspring conflict was presumed to associate with pregnancy also during the period of intensive lactation, i.e., before the weaning process ...
Smith S, Marr CM, Dunnett C, Menzies-Gow NJ.Birthweight of Thoroughbred foals has increased in recent years. It is unknown whether this is associated with increased broodmare obesity or endocrine dysfunction. Objective: To determine insulin, leptin and triglyceride concentrations in Thoroughbred mares throughout gestation and investigate their association with obesity and foal birthweight. Methods: Cohort study. Methods: A total of 66 mares were included from 40 days post-breeding. Body condition score (BCS), weight and blood samples were obtained every 60 days throughout gestation. Serum/plasma insulin, leptin and triglyceride concentr...
Ferreira CSC, Morais RCL, de Andrade ABP, Balaro MFA, Ribas JAS, Gomes GM, Pinna AE.The aim of this study was to evaluate whether the RI and PI values would help in choosing the best embryo recipient, and observe whether CL vascularization would influence P4 production. During the breeding season 2018/2019, the study was conducted using 35 mares, which is used for reference to collect data for the project on the day of embryo transfer. The utilized mares were divided into five groups followed by the day after ovulation, with D0 being the day of ovulation. Therefore, the five groups are as follows: D4-mares that were on the 4th post-ovulation day; D5-mares that were on the 5th...
Donaldson WL, Crump AL, Zhang CH, Kornbluth J, Kamoun M, Davis W, Antczak DF.Six monoclonal antibodies and ten alloantisera were used to precipitate cell surface molecules of approximately 44 kDa (class I MHC antigens) from radiolabelled equine peripheral blood lymphocytes. All ten antisera were raised against antigens of a single donor horse (horse 0834, ELA-A2,-A2). Four methods of producing antisera were compared: one or two pregnancies, skin allografting, and skin grafting followed by pregnancy. Immunization by pregnancy appeared to produce antibodies against class I products only, while skin grafting raised antibodies to class II antigens as well. Nine of the anti...
Bailey CS, Sper RB, Schewmaker JL, Buchanan CN, Beachler TM, Pozor MA, Whitacre MD.The objective of this study was to use Doppler ultrasound technology to determine whether pentoxifylline administration increased uterine blood flow in normal pregnant pony mares. Thirteen pregnant pony mares between 18 and 190 d of gestation (mean ± SEM, 101 ± 55) were utilized for the study during two trial periods. In each trial, pentoxifylline (17 mg/kg by mouth every 12h, diluted in syrup) was administered to half of the mares for 3 d, while the other mares were treated with syrup only. Doppler measurements were obtained from the right and left uterine arteries from each mare for 2 d pr...
Michel TH, Rossdale PD, Cash RS.Plasma progesterone levels were measured daily to determine the accuracy of diagnosing ovulation by rectal palpation carried out every other day; 81.5 per cent mares injected with human chorionic gonadotrophin showed increases of progesterone more than 1 ng/ml by 72 h after injection compared with 65 per cent of mares injected with gonadotrophin releasing hormone (GnRH) or saline. Mating at ovulation achieved a 74 per cent pregnancy rate in mares given hCG compared with 50 per cent given GnRH and 45 per cent controls. Diagnosis of ovulation per rectum on the basis of a pit in the ovarian surfa...
Meyers-Brown GA, Loud MC, Hyland JC, Roser JF.The most common equine breeding practice to decrease the time to the first ovulation of the year is to use artificial lights starting December 1 in the Northern Hemisphere. It can take 60-90 d for this lighting regimen to induce a fertile ovulation. The success rate for pharmaceutical compounds to carry out the same process has been variable. One compound that did induce an early ovulation was recombinant equine follicle stimulating hormone (reFSH), but neither pregnancy nor cyclicity was established in that study. Starting on December 1, 20 deep-anestrous mares of light horse breeds (4-15 y...
Fedorka CE, Ball BA, Walker OF, McCormick ME, Scoggin KE, Kennedy LA, Squires EL, Troedsson MHT.Equine abortions are attributed to both infectious and noninfectious causes. Clinical extrapolations are often made from the experimental model for ascending placentitis towards other causes of fetal compromise, including various markers of inflammation, including the cytokines IL-2, 5, IL-6, IL-10, IFNγ, and TNF. It is unknown if these cytokine changes are noted under field conditions, or if they increase preceding other pregnancy related complications. To assess this, Thoroughbred mares (n = 702) had weekly blood obtained beginning in December 2013 and continuing until parturition. Fet...
Lefranc A-, Allen WR.The diffuse noninvasive epitheliochorial equine placenta develops an intimate and complex interdigitation with the maternal endometrium throughout gestation to maximise surface contact and, consequently, optimise nutritional and gaseous maternofetal exchanges. A significant reduction occurs in the surface density of microcotyledons on the placentae of Welsh Pony vs. Thoroughbred mares that may relate to a difference in either the number or density of endometrial glands between these breeds. Objective: To examine this hypothesis and to determine the influence of the oestrous cycle upon the deve...
Ryan PL, Christiansen DL, Hopper RM, Bagnell CA, Vaala WE, Leblanc MM.Placental insufficiency is regarded as the primary factor contributing to late-term abortion and perinatal death of foals. Often when problems associated with late-term pregnancy in the horse are manifest the condition is well-advanced and therapeutic intervention may not be effective in rescuing the pregnancy. If a compromised pregnancy due to placental insufficiency could be identified early, the pregnancy might be sustained through medical intervention. Because the placenta is the sole source of circulating relaxin in the mare, we hypothesized that systemic relaxin may serve as a biomarker ...
Nagel C, Aurich C.Based on the marked variability in physiological equine gestation length, induction of foaling in mares often results in the birth of dysmature foals. Precise prediction of preparedness of the mare for foaling is thus essential. Treatment with glucocorticoids mimics the fetal signal that initiates birth. Repeated daily dexamethasone treatment in late gestation results in birth of mature foals but the time from initiation of treatment to foaling is highly variable and complications such as dystocia have been reported. Contrary to most expectations, treatment of prepartum mares with progestogens...
Palm FM, Schenk I, Neuhauser S, Schubert D, Machnik M, Schänzer W, Aurich C.Treatment with the progestin altrenogest is widely used in pregnant mares. The fact that foals born from healthy mares treated with altrenogest until term suffered from neonatal problems raises the question of direct effects of altrenogest on vital functions in the neonate. We have therefore investigated altrenogest concentrations in maternal and neonatal blood plasma and in fetal fluids. Pregnant mares were treated with altrenogest orally once daily (0,088 mg/kg bodyweight, n = 7) or left untreated (n = 8) from 280 d of gestation until foaling. Altrenogest concentration was determined in plas...
Capobianco G, Cherchi PL, Ambrosini G, Cosmi E, Andrisani A, Dessole S.Alobar holoprosencephaly is a rare and severe brain malformation due to early arrest in brain cleavage and rotation. Methods: We report a congenital anomalous fetus with alobar holoprosencephaly, prenatally diagnosed by two-dimensional (2D) sonography at the 40 weeks of gestation. The mother was affected by gestational diabetes mellitus and was obese (BMI > 30 kg/m(2)). 2D Ultrasound depicted the cerebral malformation, cyclopy, proboscis, cardiac defects (atrial septal defect, hypoplastic left heart, anomalous communication between right ventricle and aorta) and extremities defects. The new...
Jaworska J, Jaworski Z, McDonnell SM, Górecka-Bruzda A.Infanticide, related to a stallion's aggression toward a foal sired by another stallion, and feticide related to a new stallion's aggression and/or pheromonal influence (the Bruce effect) inducing loss of a fetus sired by another stallion, a female's counteraction to infanticide, have been proposed for domestic horses (Equus caballus) in human-managed conditions. The aim of the present study was, in conditions close to natural, to investigate the influence of the natural succession of a harem stallion on the mares' subsequent reproductive performance. In a population of semi-feral Konik polski...
Budik S, Palm F, Walter I, Helmreich M, Aurich C.Oxytocin (OT) and arginine vasopressin (AVP) have been detected in the yolk sac of the pre-attachment equine conceptus. Therefore, we have assessed the presence of OT and AVP receptors in equine conceptuses between Days 10 and 16 of pregnancy by qualitative PCR, quantitative PCR and immunohistochemistry. Expression of OT receptor and of the AVP receptors V1aR and V2R could be verified after sequencing the RT-PCR products of the expected length. The size of conceptuses used for quantitative PCR significantly increased with day of pregnancy (P<0.01) as did their quantitative expression of OTR...
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 ...
Vandeplassche M.The author reviews 40 years of clinical experience including more than 1000 cases of dystocia in mares of different breeds. The high incidence of stillbirth and perinatal mortality of the foal, severe lesions of the genital tract developing during foaling and in the early post partum period are discussed and suggestions made for their prevention and treatment. The advantages of partial embryotomy to avoid unnecessary caesarean sections are emphasised. Special attention is given to the causes of and approach to cases of prolonged gestation; to dystocia caused by retroversion of preparturient to...
Aitken RJ, Lambourne S, Medica AJ.A capacity to predict the likelihood of pregnancy following natural matings would be of considerable benefit to the Thoroughbred horse breeding industry. In this article, we describe a strategy for achieving this outcome through the analysis of dismount samples, that achieved an overall accuracy of 94.6%. The purpose of this study was to determine whether the analysis of dismount semen samples from Thoroughbred stallions could be used to predict whether a given mating would result in a pregnancy. The analysis was based on 143 matings of 141 mares by a cohort of 7 Thoroughbred stallions over a ...
Kastelic JP, Adams GP, Ginther OJ.Luteal progesterone was removed by an injection of prostaglandin F2alpha or bilateral ovariectomy on Day 12 of pregnancy in pony mares. The embryonic vesicle remained mobile in the uterus until loss occurred on Days 13, 13, 15, or 19 in four prostaglandin-treated mares and Days 15, 17, 19, or 26 in four ovariectomized mares. Exogenous progesterone given daily, starting on Day 12, maintained pregnancy until Day 40 in five of five prostaglandin-treated and three of four ovariectomized mares. During two-hour mobility trials on Day 14, embryonic vesicles in mares without luteal or exogenous proges...
Hemberg E, Lundeheim N, Einarsson S.To minimize the number of matings/inseminations, controlled ovulation has been practised since a long time ago. A potent short-term implant, releasing the GnRH analogue deslorelin (Ovuplant((R))) has been used in Australia and North America for several years for hastening the ovulation time in mares, but the product is not registered on the European market. This study was aimed to investigate: (1) ovulation time in mares implanted with Ovuplant when the largest follicle was 42 mm or more in size, (2) repeatability of ovulation time in successive oestruses when treated with Ovuplant, (3) pregna...
De Coster T, Van Poucke M, Bogado Pascottini O, Angel-Velez D, Van den Branden E, Peere S, Papas M, Gerits I, Govaere J, Peelman L, Vermeesch JR....In addition to fulfilling many breeders' curiosity, equine embryonic sex determination can have a profound commercial impact. However, the application of currently described assays for equine embryonic sexing has rendered variable diagnosis and validation rates, with sensitivity being the main problem. In addition, while pregnancy results of in vivo-flushed equine embryos following a needle aspiration biopsy equal those of non-biopsied embryos, the effect on in vitro-produced embryos is unknown. Here, we aimed to develop a highly sensitive and specific assay for equine sex determination that c...
