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Topic:Pregnancy
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.
The effect of oxytocin and PGF2alpha on the uterine involution and pregnancy rates in postpartum Arabian mares. In this study, the effects of oxytocin and an analog of prostaglandin (cloprostenol) on the uterine involution and pregnancy rates were investigated. Mares received 3 ml of 0.9% NaCl in Group C (n=10), 30 IU/mare of oxytocin in Group O (n=10) and 250 microg/mare of cloprostenol in Group P (n=10) within 12h after parturition. The gravid uterine horn's cross-sectional diameter was measured by ultrasonography. The mean uterine diameters did not differ significantly between the treatment (O and P) and the control (C) groups (p>0.05). The difference between the postpartum ovulation periods (Grou...
Desialylation of core type 1 O-glycan in the equine embryonic capsule coincides with immobilization of the conceptus in the uterus. During the second and third weeks of pregnancy, the equine conceptus expands rapidly while it is enclosed within a glycan capsule. Around day 16 of gestation, the conceptus loses its mobility in the uterus by a process termed 'fixation', coinciding with various changes in the capsule. Here, we compared the structure of the carbohydrate moieties expressed by the capsule during pre- and post-fixation periods. The glycan structures were studied by chemical analyses in combination with mass spectrometry. Capsule material from conceptuses collected before fixation (days 13-16) was observed to carry...
Proliferative processes within the equine corpus luteum may depend on paracrine progesterone actions. Soon after ovulation, the corpus luteum (CL) starts secreting progesterone (P(4)), a hormone necessary for implantation. The aim of the study was to evaluate whether P(4) exerts an autocrine/paracrine action on luteal angiogenic activity and P(4), prostaglandin E(2) (PGE(2)) and NO production in the mare. Corpora hemorrhagica (CH) and mid-luteal phase CL (MCL) were cultured with (i) no hormone (Control); (ii) P(4); (iii) a P(4) precursor - pregnenolone; or (iv) a P(4) antagonist - onapristone [10(-4) M;10(-5) M; all steroids]. NO production decreased in MCL, with respect to CH, when treated wi...
Retrospective study of dystocia in mares at a referral hospital. The period between the onset of dystocia and its resolution has an important bearing on fetal outcome. There are few published data on which to base decisions regarding optimum management of cases in practice. Objective: To evaluate and compare the effects of a coordinated dystocia management protocol (CDMP) with that of a previous protocol of random management on time to resolution and outcome in both an emergency dystocia referral population of mares (referred emergency cases: EM) and in a population of mares residing in hospital due to high risk pregnancy (HRP) concerns that then experience...
Urinary excretion of 5(10)-estrene-3beta,17alpha-diol and estrone by the female horse: complementary indicators of early pregnancy screened with regard to a putative anabolic doping practice. Rules of horse racing stipulate that pregnant mares may compete under definite conditions of date, because early pregnant status may be misused for the sake of enhancing physical performance by putative anabolic steroid action. Screening for pregnancy is generally performed by plasma equine gonadotrophin (eCG) immunoassay, which covers the period between Days 40 and 120. In common screening for urinary anabolic steroids performed by gas chromatography-mass spectrometry, inclusion of two complementary criteria, i.e. the evaluation of total conjugates of 5(10)-estrene-3beta,17alpha-diol (EED) an...
Effects of coitus and the artificial insemination of different volumes of fresh semen on uterine contractions in mares. Uterine contractions may play an important role in the transportation of spermatozoa towards the site of fertilisation in the oviduct of mares. M-mode ultrasound was used to measure the number, amplitude and duration of uterine contractions in each uterine horn and the uterine body of oestrous mares for four minutes before and four minutes after either coitus, or the artificial insemination of either 80.0 ml of fresh semen or 10.0 ml of fresh semen. The direction of the uterine contractions in each uterine horn and the uterine body was measured before and after coitus. Coitus and the inseminat...
Management of postfixation twins in mares. Methods to manage twins after fixation include natural reduction,dietary reduction, transvaginal ultrasound-guided aspiration,surgical removal, craniocervical dislocation, and transabdominal ultrasound-guided injection. Of these, results have been inconsistent with regard to producing a single healthy foal, except for craniocervical dislocation. This new technique enables the twin to be reduced before complete placenta formation has occurred, allowing the remaining fetus to use the entire endometrial surface and grow to its full potential.
Diagnosis and treatment of equine placentitis. Equine placentitis is a complex disease that has devastating consequences for horse owners. Placentitis is a significant cause of foal loss annually. Prompt diagnosis and treatment of the disease are paramount for survival of the affected neonate. This article discusses current information on pathogenesis of the disease as well as diagnostic and therapeutic options.
Advanced insemination techniques in mares. Advanced artificial insemination techniques, such as deep uterine,hysteroscopic, oviductal, and intrafollicular insemination, are described in the context of the different types of spermatozoa that are now available for insemination, including fresh, chilled, frozen,sex-sorted, and epididymal spermatozoa. The implementation of these new technologies answers and poses questions about the interactions of sperm and oocytes in vivo.
Vitrification of equine embryos. Vitrification can be used successfully to cryopreserve equine embryos. Embryos for vitrification should be collected from donor mares' uteri when they are 300 mm or less in diameter, however,and at the morula or early blastocyst stage of development. No special equipment is required for vitrification; the straw containing the embryo is exposed to vapor for 1 minute before plunging it into liquid nitrogen. Warming of the straw requires no special equipment,and the embryo can be transferred directly from the straw into a recipient's uterus. Vitrification has been repeatedly successful when the p...
Hormone profiles and treatments in the late pregnant mare. Evaluation of hormone profiles in late pregnancy is one of the major determinants of fetoplacental compromise in equine clinical practice. Use of hormone therapies is subjective and reflects, to a large extent, our lack of understanding about the endocrine relations between the mare, placenta, and fetus. This article describes the normal endocrine events in late gestation, the abnormal hormone patterns associated with fetoplacental dysfunction, and the hormone interventions that are currently used or could be used to improve pregnancy outcome.
Diagnosis of the compromised equine pregnancy. Identification of a compromised pregnancy in the mare requires the exhaustive collection of a database that includes past and recent reproductive and medical histories and a variety of parameters indicating fetal distress and possibly suggesting neonatal compromise.Judicious interpretation of findings and serial recording of data throughout gestation may help in the early detection of abnormal fetomaternal exchange pathways. Some sources of compromise may be identified, and the impact on fetomaternal well-being maybe calculated. Appropriate preventive or corrective measures may then be impleme...
Transrectal ultrasonography and plasma progestin profiles identifies feto-placental compromise in mares with experimentally induced placentitis. Transrectal ultrasonography of the caudal uterus and a progestin profile were evaluated for accuracy in identifying mares with feto-placental compromise in a model of placentitis. Twenty-two pregnant ponies were divided into four groups: (1) control mares (n=5); (2) instrumented controls (n=2); (3) instrumented inoculated mares (n=11); (4) inoculated mares (n=4). Mares in Groups 3 and 4 were inoculated with Streptococcus equi subsp. zooepidemicus. Maternal plasma progestins, vulvar discharge, mammary gland development, combined thickness of the uterus and placenta (CTUP) and placental separati...
Effects of a Streptococcus equi infection–mediated nutritional insult during mid-gestation in primiparous Thoroughbred fillies. Part 1: placental and fetal development. There is a paucity of information on factors that influence placental development in the horse. Objective: Changes in nutrition, particularly around the time of proliferative placental growth, can affect development of the placenta and fetal growth. Objective: To investigate the effects of 2 planes of nutrition and an unforeseen infection-mediated nutritional insult on placental and fetal development in the mare. Methods: Twenty maiden Thoroughbred fillies, age 3 or 4 years, mated to one Thoroughbred stallion, were maintained on either High or Moderate food intake throughout pregnancy. In mid-...
Effects of reproductive status and management on cortisol secretion and fertility of oestrous horse mares. Stressful events may contribute to low reproductive efficiency due to glucocorticoid-mediated inhibition of hormone secretion in a variety of species. We therefore investigated effects of stress related to management of mares around artificial insemination on secretion of cortisol and fertility parameters. To avoid further disturbance of mares by frequent blood sampling, faecal cortisol metabolites (fCM) were determined instead (sample collection at 8-h intervals). A total of 50 mares (16 maiden, 17 barren, 12 foaling, 5 teaching mares) were included in the study. Mares were brought to the AI ...
Successful timing of ovulation using deslorelin (Ovuplant) is labour-saving in mares aimed for single ai with frozen semen. 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...
Effect of rostrocaudal mobility of the mandible on feed digestibility and fecal particle size in horses. To evaluate the effect of rostrocaudal mobility (RCM) of the mandible during extension and flexion of the atlanto-occipital joint on weight gain, feed digestibility, and fecal particle size in horses. Methods: Randomized controlled trial. Methods: 34 pregnant mares housed in 1 barn. Methods: Horses were randomized into a treatment (n = 17) or control (17) group. All horses were sedated, and the distance between the rostral portions of the upper and lower incisor arcades was determined during extension and flexion of the atlanto-occipital joint; mandibular RCM was calculated as the difference b...
Alobar holoprosencephaly, mobile proboscis and trisomy 13 in a fetus with maternal gestational diabetes mellitus: a 2D ultrasound diagnosis and review of the literature. 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...
Developmental competence of equine oocytes and embryos obtained by in vitro procedures ranging from in vitro maturation and ICSI to embryo culture, cryopreservation and somatic cell nuclear transfer. 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...
Meclofenamic acid extends donor-recipient asynchrony in equine embryo transfer. A level of synchrony between embryo and uterine environment is essential for the establishment of pregnancy when performing embryo transfer. The ability to extend the acceptable degree of asynchrony would allow more efficient use of recipient mares. Objective: To establish if administration of the prostaglandin synthetase inhibitor, meclofenamic acid, to asynchronous recipient mares could widen the acceptable window of asynchrony for embryo transfer. Objective: The prostaglandin synthetase inhibitory action of meclofenamic acid may act to suppress luteolysis and thereby allow for a greater deg...
Influence of induction of parturition on the neonatal acute phase response in foals. The objectives of the present study were to determine whether induction of parturition in mares at term with low doses of oxytocin (2.5 i.u. i.v. every 20 min) affected the incidence of peri-partum complications or inflammatory responses in the neonatal foal. Parturition was induced in 11 of 26 mares and the remainder foaled spontaneously. Serum concentrations of amyloid A (AA; an acute phase protein) were measured (with a commercial ELISA) from 0 to 72 h postpartum in 18 of the neonatal foals. The incidence of dystocia and premature placental separation was higher in induced mares (2 of 11 an...
Lactoferrin expression in the horse endometrium: relevance in persisting mating-induced endometritis. Lactoferrin (LF) is an estrogen-regulated glycoprotein with well-described antibacterial and immunomodulatory properties. The present study is the first report on LF expression in horse endometrial specimens. Mares chosen for the study were either resistant or susceptible for persisting mating-induced endometritis (PMIE) during the natural ovulatory cycle and in early pregnancy. Our investigations included immunostaining for LF protein and CD18, a leukocyte marker, as neutrophils are a possible source for LF in the endometrium. Quantification of LF mRNA was performed by use of real-time RT-PCR...
Aspiration of oocytes from transitional, cycling, and pregnant mares. The aim of this study was to compare the efficacy of three approaches for recovering equine oocytes via transvaginal ultrasound-guided follicular aspiration. Fourteen mares were used as oocyte donors during the spring transition period and physiologic breeding season, and 11 mares were bred for use as oocyte donors during early gestation. In all mares, large (>20 mm) and small (10-20 mm) follicles were aspirated in eight rounds every 10-11 days. In each of the four rounds during the transition period, half the mares received 12.5 mg eFSH once daily for 4 days prior to aspiration. For each of t...
Fertility of frozen-thawed stallion semen cannot be predicted by the currently used laboratory methods. The aim of the project was to use current simple and practical laboratory tests and compare results with the foaling rates of mares inseminated with commercially produced frozen semen. In Exp. 1, semen was tested from 27 and in Exp. 2 from 23 stallions; 19 stallions participated in both experiments. The mean number of mares per stallion in both experiments was 37 (min. 7, max. 121). Sperm morphology was assessed and bacterial culture performed once per stallion. In Exp. 1, progressive motility after 0, 1, 2, 3, and 4 h of incubation using light microscopy, motility characteristics measured wit...
Oxytocin does not contribute to the effects of cervical dilation on progesterone secretion and embryonic development in mares. The aim of the present study was, to investigate the effects of oxytocin administration on Day 7 post-ovulation on progesterone secretion, pregnancy rate and embryonic growth in mares. Endogenous stimulation of oxytocin release was compared to the administration of native oxytocin or the long-acting oxytocin analogue carbetocin. At Day 7 after ovulation, mares had to undergo four treatments in a crossover design: (a) control, (b) oxytocin (10 IU i.v.), (c) carbetocin (280 microg i.m.) and (d) cervical dilation. On Day 13, all mares (8 of 8 mares) were pregnant on groups control, oxytocin and c...
Insemination doses: how low can we go? This manuscript presents a brief historical review of investigations related to equine artificial insemination. The origin of recommended insemination doses for use fresh, cooled and frozen semen will be reviewed. Over 30 years ago, an insemination dose of 500 x 10(6) progressively motile sperm (PMS) was recommended to maximize pregnancy rates when mares were bred with fresh semen under less than ideal conditions. Since that time, 500 x 10(6) progressively motile sperm has been almost universally accepted as a standard insemination dose, regardless of a stallion's fertility or the refinements ...
Production of horse foals via direct injection of roscovitine-treated donor cells and activation by injection of sperm extract. We evaluated the effects of different donor cell treatments and activation methods on production of blastocysts after equine nuclear transfer. Nuclear transfer was performed by direct injection of donor cells, using a piezo drill, and standard activation was by injection of sperm factor followed by culture with 6-dimethylaminopurine. There was no difference in blastocyst development between embryos produced with roscovitine-treated or confluent donor cells (3.6% for either treatment). Addition of injection of roscovitine or culture with cycloheximide at the time of activation did not affect bl...
Equine frozen semen: freezability and fertility field results. The freezability of stallion semen defined as the number of selected ejaculates/total number of ejaculates frozen from 161 different stallions was analyzed. Of the stallions, 19, 30, 27 and 24% had a freezability of 0%, 0 to 33%, 33 to 66%, over 66%, respectively In 85 different stallions, the correlation of freezability between first and second year was 0.60 (P < 0.001). The relationship between fertility with fresh and frozen semen and freezability was analyzed in 40 stallions whose freezability and fertility information was recorded during 5 years. There was a strong relationship between fe...
The effects of parturition and peripartum complications on the peritoneal fluid composition of mares. Abnormalities in peritoneal fluid are diagnostically useful for managing equine colic; however, their significance in post-dystocia mares is not known. This study was to determine what changes, if any, occurred following obstetrical manipulations. Peritoneal fluid samples were collected from 2 groups of foaling mares to establish control values, and from a third group that had developed clinical abnormalities (CAb,n = 14) or had made an uneventful recovery (CN,n = 36) following fetal extraction. In Group 1 mares, samples were collected before and after induced parturitions (n = 7), and althoug...
