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.
Klein C, Scoggin KE, Troedsson MH.Establishment of pregnancy is critically dependent upon a precisely orchestrated embryo-maternal interaction leading to a receptive uterine environment. The up-regulation of the interferon-stimulated protein 15 kDa (ISG15) during pregnancy has been described in various species and has been hypothesized to be part of the molecular repertoire that makes the uterus receptive to conceptus development. In the current study, the expression of ISG15 and enzymes involved in ISG15ylation was examined at the mRNA and protein level in equine endometrium at Day 14 of the luteal phase and at Day 14 and 50 ...
Krakowski L, Krawczyk CH, Kostro K, Stefaniak T, Novotny F, Obara J.The study involved 46 healthy purebred Arabian mares exhibiting regular oestrous cycles that underwent artificial insemination (AI). Pregnancy was detected ultrasonographically (US) in 40 mares. In 15 mares in foal, early embryonic death (EED) was observed during the pregnancy days 14-21. Blood for determinations of serum acute phase proteins (SAA and Hp) and progesterone (P4) was sampled 12-24 h before ovulation and the first insemination, at 12, 24, 72, 96 h and on day 7, 10, 14, 21, 35 and 55 after ovulation. The results revealed that in 25 mares without EED, the serum levels of P4, SAA and...
Oddsdóttir C, Riley SC, Leask R, Shaw DJ, Aurich C, Palm F, Fowden AL, Ricketts SW, Watson ED.During late gestation in the mare, rapid fetal growth is accompanied by considerable placental growth and further invasion of the endometrium by microvilli. This growth requires extensive remodeling of the extracellular matrix (ECM). In early pregnancy, we know that matrix metalloproteinase (MMP)-9 and -2 are involved in the endometrial invasion during endometrial cup formation. The present study investigated whether MMPs are found in fetal fluids later in gestation and during parturition, and if there was a difference in their activities between normal and preterm delivery. Amniotic fluids we...
Satué K, Domingo R.During pregnancy, the coordinated interaction of the components of the renin-angiotensin-aldosterone system (RAAS) plays a vital role in accommodating the cardiovascular, haemodynamic and haematological needs imposed by foetal development and the placenta. This significantly influences the birth weight of the neonate and foetal viability. Although the evolution of each of the components of this system has been widely described in various species, it has not yet been clarified in the mare. Thus, the objectives of the present research were: 1) to establish reference values for renin (REN), angio...
Smits K, Goossens K, Van Soom A, Govaere J, Hoogewijs M, Peelman LJ.In vitro-produced (IVP) equine blastocysts can give rise to successful pregnancies, but their morphology and developmental rate differ from those of in vivo-derived equine blastocysts. The aim of the present study was to evaluate this difference at the genetic level. Suppression subtractive hybridisation (SSH) was used to construct a cDNA library enriched for transcripts preferentially expressed in in vivo-derived equine blastocysts compared with IVP blastocysts. Of the 62 different genes identified in this way, six genes involved in embryonic development (BEX2, FABP3, HSP90AA1, MOBKL3, MCM7 a...
Klein C, Troedsson MH.Establishment and maintenance of pregnancy are critically dependent on embryo-maternal communication during the preimplantation period. The horse is one of the few domestic species in which the conceptus-derived pregnancy recognition signal has not been identified. To gain new insights into the factors released by the equine conceptus, transcriptional profiling analyses of conceptuses retrieved 8, 10, 12, and 14 days after ovulation were performed using a whole-genome microarray. Selected array data were confirmed using quantitative PCR, and the expression of proteins of interest was confirmed...
Heckenbichler S, Deichsel K, Peters P, Aurich C.Stallion semen processing is far from standardized and differs substantially between AI centers. Suboptimal pregnancy rates in equine AI may primarily result from breeding with low quality semen not adequately processed for shipment. It was the aim of the study to evaluate quality and fertility of cooled-shipped equine semen provided for breeding of client mares by commercial semen collection centers in Europe. Cooled shipped semen (n = 201 doses) from 67 stallions and 36 different EU-approved semen collection centers was evaluated. At arrival, semen temperature was 9.8 ± 0.2 °C, mean sperm ...
Wilsher S, Allen WR.The maternal recognition of pregnancy (MRP) signal in the mare has not been determined, although oestrogens have been proposed as a potential candidate. Objective: To determine effects of intrauterine administration of oestrogen and various oils on cyclic luteolysis in the mare. Objective: Intrauterine oestradiol or fatty acids may suppress luteolysis in the cycling mare when administered during late dioestrus. Methods: A single 1 ml dose of slow-release oestradiol (10 mg/ml) in fractionated coconut oil was infused into the uterine lumen of cycling mares on Days 6, 8, 10, 12 or 14 post ovulati...
Willmann C, Schuler G, Hoffmann B, Parvizi N, Aurich C.The treatment of early pregnant mares with a history of repeated early embryonic loss with the progestin altrenogest has become routine; however no controlled studies on the efficiency of altrenogest to prevent embryonic losses are available so far. In the present study, we have investigated effects of altrenogest treatment in mares on conceptus development and the secretion of LH, progesterone, and eCG until day 100 of pregnancy. In addition, differences related to age of mares were assessed. Mares were treated with altrenogest (0.044 mg/kg per os once daily) or sunflower oil (10 ml per os on...
Kikuchi M, Nakano Y, Nambo Y, Haneda S, Matsui M, Miyake Y, Macleod JN, Nagaoka K, Imakawa K.A factor responsible for progression to pregnancy establishment in the mare has not been definitively characterized. To identify factors possibly involved in the establishment of equine pregnancy, the endometrium was collected from day 13 (day 0=day of ovulation) cyclic and day 13, 19 and 25 pregnant animals. From initial subtractive hybridization studies, a calcium regulating factor, Stanniocalcin-1 (STC1) mRNA, was found as a candidate molecule expressed uniquely in the pregnant endometrium. Endometrial expression of STC1 mRNA was noted on day 19 and was markedly increased in the day 25 grav...
Newcombe JR, Cuervo-Arango J.One hundred and fifty-four mares were inseminated with fresh semen either during the pre- or post-ovulatory periods at different intervals relative to ovulation: 36-24 h (n = 17) and 24-0 h (n = 30) before ovulation; 0-8 h (n = 21), 8-16 h (n = 24), 16-24 h (n = 48) and 24-32 h (n = 14) h after ovulation. All mares received the same routine post-mating treatment consisting of an intrauterine infusion with 1 litre of saline and antibiotics followed 8 h later by an intravenous administration of oxytocin. Artificial inseminations (AI) from 36 h before ovulation up to 16 h post-ovulation were perf...
Morrell JM, Mari G, Kútvölgyi G, Meurling S, Mislei B, Iacono E, Rodriguez-Martinez H.Some stallions produce ejaculates of low quality and/or low fertility when used for artificial insemination (AI). The purpose of these five case studies was to use Single Layer Centrifugation (SLC) to select the best spermatozoa from 'problem' ejaculates for subsequent use in AI. Sperm quality, in terms of motility, morphology and chromatin integrity, was improved in the SLC-selected samples compared to the corresponding uncentrifuged samples, with the exception of one stallion thought to have ampullary stasis. In this stallion, neither the incidence of spermatozoa with detached heads nor the ...
Newcombe JR, Paccamonti D, Cuervo-Arango J.Data were analysed retrospectively from fourteen breeding seasons at an Equine Fertility Clinic for the effect of interval between pre- and postovulatory examinations for immediate postovulatory insemination on pregnancy rate (PR) and embryo loss rate (ELR). Mares of various breeds and ages were examined at intervals which varied from 0.5 to 15h between the pre- and postovulatory period over 867 cycles. When ovulation was detected they were inseminated with a single dose of commercial frozen-thawed semen. All mares were treated in the post-insemination period with intrauterine antibiotics and ...
Panzani D, Zicchino I, Taras A, Marmorini P, Crisci A, Rota A, Camillo F.Artificial photoperiod treatment is currently the best method to hasten the first ovulation of the breeding season in winter anoestrus mares. However, this is not easy to apply in large herds of mares and, to be effective, has to be planned in the northern hemisphere in December at the latest. Pharmacological treatments have been proposed as alternatives: GnRH agonists, progesterone or its synthetic agonist Altrenogest, and dopamino-antagonists, as pherphenazine, domperidone or sulpiride. Dopamino-antagonists protocols, beginning at a given day of the year, gave controversial results in terms ...
Choi YH, Gustafson-Seabury A, Velez IC, Hartman DL, Bliss S, Riera FL, Roldán JE, Chowdhary B, Hinrichs K.The equine embryo possesses a capsule that is considered essential for its survival. We assessed viability after breaching the capsule of early (Day 6) and expanded (Day 7 and 8) equine blastocysts by micromanipulation. The capsule was penetrated using a Piezo drill, and trophoblast biopsy samples were obtained for genetic analysis. Pregnancy rates for Day-6 embryos, which had intact zonae pellucidae at the time of recovery, were 3/3 for those biopsied immediately after recovery and 2/3 for those biopsied after being shipped overnight under warm (∼28 °C) conditions. The pregnancy rates for ...
Atayde L, Rocha A.It is important to get mares pregnant as early as possible after vernal transition and thus, identification signs of impending 1st ovulation of the year are warranted. To identify clinical indicators of an approaching first ovulation of the year, mares were teased with a stallion for oestrous detection starting January 3 and subjected to ultrasonographic examination. Day of first appearance of uterus oedema, follicular wall invagination, intrafollicular echogenicity, double contour of the follicle wall, increase in granulosa thickness, follicular wall hyperechogenicity and appearance of pear-s...
Bondo T, Jensen SK.This study assessed the effect of a vitamin E supplement given to pregnant mares on immunoglobulins (Ig) levels in foals. In addition, the fatty acid (FA) content and composition of the mares' milk was assessed. Milk α-tocopherol concentrations were compared between pregnant Danish Warmblood mares (n = 17) given a daily oral supplement of 2500 international units (IU) RRR-α-tocopherol in the last 4 weeks of pregnancy and a group of unsupplemented mares (n = 17) receiving 170-320 IU vitamin E daily originating from the feed. Milk α-tocopherol was higher in supplemented mares (36.7, 12.4 and ...
Satué K, Muñoz A, Blanco O.In order to investigate the effect of pregnancy on equine hematological profile, venous blood samples were taken from 44 Carthusian broodmares every two weeks during pregnancy, divided into three periods: I (conception to 110 days), II (111-220 days) and III (222 days to delivery). Routine hematological analysis was performed. Packed cell volume (PCV) increased in period II probably as a consequence of the climatic conditions or as a result of physical stress of lactation during period I. After that, a reduction in PCV was found but this was not matched with a similar decrease in total serum p...
Atli MO, Kurar E, Kayis SA, Aslan S, Semacan A, Celik S, Guzeloglu A.The aim was to evaluate expression of genes involved in the biosynthesis of prostaglandins (PTG), Prostaglandin H Synthase-1 (PTGS1) and PTGS2, PGF synthase (PTGFS), and PGE synthase (PTGES), PGF receptor (PTGFR), PGE receptors (PTGER2 and PTGER4), prostaglandin transporter (SLCO2A1) and hydroxyprostaglandin dehydrogenase-15 (HPGD). Endometrial biopsies were obtained from mares on day of ovulation (d0, n=4), late diestrus (LD, n=4), early luteolysis (EL, n=4) and after luteolysis (AL, n=4) during the cycle. Stages of the cycle were confirmed by plasma progesterone concentrations measured daily...
Aurich C, König N, Budik S.In mares, repeated embryo collection in successive oestrous cycles is necessary if a greater number of foals should be produced. We investigated effects of repeated embryo collection in fertile donor mares on embryo recovery rates. In addition, an influence of the individual mare and season on embryo recovery rates was studied. In nine mares, a total of 153 embryo collections were performed during 30 months (17 ± 2.2 embryo collections per mare). The overall embryo recovery rate was 64% and did not differ among mares. Between successive embryo collection procedures, recovery rate varied signi...
LeBlanc MM.Ascending placentitis is a common cause of premature birth, abortion and delivery of compromised, ill foals. Recent experimental models have investigated diagnostic procedures and treatment strategies in an attempt to improve live foal rate. Diagnostics such as transrectal and transabdominal ultrasonography are used to evaluate foetal well-being and placental separation, while measurement of plasma progestins or oestrogen identifies a stressed or hypoxic foetus. Treatment is directed at stopping spread of infection, maintaining uterine quiescence and blocking production of pro-inflammatory cyt...
Hinrichs K.In vitro embryo production is possible in the horse both clinically and for research applications. Oocytes may be collected from excised ovaries post-mortem, or from either immature follicles or stimulated pre-ovulatory follicles in the live mare. In vitro maturation of immature oocytes typically yields approximately 60% mature oocytes. As standard in vitro fertilization is not yet repeatable in the horse, fertilization is performed by intracytoplasmic sperm injection. Embryo culture requires medium with high glucose, at least during blastocyst development, and rates of blastocyst development ...
Ababneh M, Ababneh H, Shidaifat F.Phospholipase A2 (PLA2) is a key enzyme for biosynthesis of PGF2α. Real-time RT-PCR and immunohistochemistry were used to determine transcription and cellular distribution of cytosolic PLA2 (cPLA2) in the equine endometrium during the oestrous cycle and early pregnancy. Endometrial biopsy and blood samples were collected from cycling mares on days (d) 8, 11, 15 and 18 (oestrus) (Day 0 = Day of ovulation; n = 5 for each day) and from pregnant mares (n = 4) on d15. Except for mares on d18 and some cyclic mares (n = 2) on d15 with low progesterone (P₄) concentrations (< 3.18 nm), P₄ conce...
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...
Noronha LE, Antczak DF.The horse has proven to be a distinctively informative species in the study of pregnancy immunology for several reasons. First, unique aspects of the anatomy and physiology of the equine conceptus facilitate approaches that are not possible in other model organisms, such as non-surgical recovery of early stage embryos and conceptuses and isolation of pure trophoblast cell populations. Second, pregnant mares make strong cytotoxic antibody responses to paternal major histocompatibility complex class I antigens expressed by the chorionic girdle cells, permitting detailed evaluation of the antigen...
Novak S, Smith TA, Paradis F, Burwash L, Dyck MK, Foxcroft GR, Dixon WT.The global proteome of sperm and seminal plasma of fertile stallions was investigated to determine whether associations with relative in vivo fertility exist. Seven stallions at stud in a commercial breeding station were collected throughout the breeding season and bred to a total of 164 mares to determine conception rates. On three occasions during the breeding season, raw semen was obtained from a regular collection for proteomic analysis using two-dimensional electrophoresis and also assessed for routine semen quality end points. First cycle conception rate was negatively related to ejacula...
Lopes Ede P, Siqueira JB, Pinho RO, Guimarães JD, Rocha AN, de Carvalho GR, Torres CA.The objective of this study is to evaluate the reproductive efficiency in donors and recipient Mangalarga Marchador mares in commercial programmes of embryo transfer (ET) and the effects of some reproductive characteristics and ET methodology on conception rates in the recipient mares. A total of 1140 flushing procedures were performed and 830 embryos (72.8%) were recovered. There were no differences between the rates of embryonic recovery in the different breeding seasons (p > 0.05) and 92.8% of the recovered embryos were 8-9 days old. There was no difference in the embryonic recovery regardi...
Martinez M, Modric S.In veterinary medicine, the characterization of a drug's pharmacokinetic (PK) properties is generally based upon data that are derived from studies that employ small groups of young healthy animals, often of a single breed. These are also the data from which population predictions are often generated to forecast drug exposure characteristics in the target population under clinical conditions of use. In veterinary medicine, it is rare to find information on the covariates that can influence drug exposure characteristics. Therefore, it is important to recognize some of the factors that can alter...
Jalim SL, McKinnon AO.To evaluate the fertility of mares bred at various intervals relative to surgical management of rectovaginal fistula (RVF). Methods: Surgical repair of RVF was performed in 28 mares at variable times relative to foaling (30 days to 24 months) and also relative to rebreeding (same cycle or delayed). Postoperative fertility was then evaluated. Results: Two mares were already pregnant at the time of surgery and 20 of 23 mares (87%) that were bred immediately prior to or following surgery conceived from their first service. When mares were bred in the same cycle as surgery, the next cycle followin...
Maziero RRD, Guaitolini CRF, Guasti PN, Monteiro GA, Martin I, Silva JPMD, Crespilho AM, Papa FO.Studies involving different methods and techniques of cryopreservation and its interactions with the conception rates in artificial insemination (AI) programs are reported in the literature. This study evaluated the sperm kinetics, plasma membrane integrity, and fertility rates of mares inseminated with cryopreserved stallion semen subjected to different freezing methods. For this, four ejaculates from five stallions were collected and frozen in conventional (Styrofoam box) or automated system in Mini-Digitcool ZH 400. Seminal samples were evaluated after thawing for sperm motion parameters by...
Hoffman RM, Kronfeld DS, Cooper WL, Harris PA.The glucose tolerance test in the horse may be used to determine metabolic responses to diet, disease, or physiologic state. The objective of this study was to determine the effect of reproductive stage (gestation and lactation) and supplemental dietary energy source (sugar and starch [SS] or fiber and fat [FF]) on glucose metabolism in grazing mares using an oral glucose tolerance test. Twelve mares, six on each supplement, were examined on three occasions: one in the third trimester of pregnancy, the second in early lactation, and the third in late lactation. During each test, venous samples...
Jones CJP, Allen WRT, Wilsher S.In this study, we compare glycosylation at the fetomaternal interface in 3 equine species: horse, donkey and zebra, all of which can interbreed to produce hybrids, to assess their glycan similarities and differences. Methods: Sections cut from 3 specimens of horse (Equus caballus) placenta (50, 200 and 280 days gestation), one donkey (Equus asinus) placenta (65 cm crown-rump length) and 5 specimens of zebra (Equus quagga) placentae (81-239 days gestation) were stained with a panel of 24 biotinylated lectins using an avidin-peroxidase revealing system. Results: There were only slight quantitat...
Ousey JC, Kölling M, Newton R, Wright M, Allen WR.Aged mares with endometrosis suffer higher rates of pregnancy loss than young mares, due to poor placental development. Reduced uterine blood supply may be one contributory factor. Objective: To measure uterine artery (UA) blood flow and other Doppler indices throughout pregnancy and compare placental and foal development in young mares and aged mares. Methods: Thoroughbred mares were grouped according to age and endometrial biopsy score: 1) 6 young mares (mean age 7.3 years, Category ); 2) 6 aged mares (mean age 18.3 years, Category II). Vascular pathology was nil or mild except in one aged m...
Keith L, Ball BA, Scoggin K, Esteller-Vico A, Woodward EM, Troedsson MH, Squires EL.The objectives were to: (1) evaluate the efficacy of varying intervals of oxytocin administration in preventing luteolysis in mares; (2) examine PGF(2α) release in mares experiencing prolonged diestrus secondary to oxytocin treatment; and (3) evaluate the endometrial expression of oxytocin receptor, estrogen receptor α, and prostaglandin synthesis enzymes after oxytocin administration. In experiment I, mares received oxytocin (60 IU, im) daily on Days 8 to 10, 8 to 12, or 8 to 14 postovulation, and control mares received sterile saline. Prolongation of diestrus was defined by elevation of se...
Sirois J, Betteridge KJ, Goff AK.The outcome of 23 collections and reinsertions of conceptuses on Days 10.5-13.5, 4 transfers of Day-10.5, and 13 transfers of Day-6.5 embryos (ovulation = Day 0) was monitored in 30 mares. Blood samples were taken before and after each procedure to measure plasma 15-keto-13,14-dihydroprostaglandin F-2 alpha (PGFM), and then daily for progesterone determinations. Mares were also subjected to daily teasing for detection of oestrus, and to uterine ultrasonography for tracing the development of the conceptus. After the reinsertions, 12/23 conceptuses were detectable immediately after the procedure...
Macpherson ML, Chaffin MK, Carroll GL, Jorgensen J, Arrott C, Varner DD, Blanchard TL.To compare effects of 3 oxytocin-based induction techniques on fetal and neonatal foals. Methods: Prospective randomized controlled trial. Methods: 16 pregnant mares. Methods: Parturition was induced in mares by use of 3 treatments: group 1, 75 U of oxytocin, IM; group 2, 15 U of oxytocin, IM, q 15 minutes, for a maximum of 75 U; group 3, 75 U of oxytocin in 1 L of 0.9% NaCl solution IV (1 U/min), for a maximum of 75 U. Blood gas values and indices of vitality were measured in foals, and variables describing parturition were measured in mares. Results: Group-3 mares had a shorter interval from...
Boening KJ, Leendertse IP.The medical records of pregnant mares over a 3-year period were reviewed. In all cases persistent pain or progressive abdominal distension were the main reason for referral. The overall survival rate for the 115 mares treated for colic was 73.9% (85 cases). The abortion rate was 20.5% in surgical patients (34 cases), 40% (5 cases) for mares with uterine torsions and 10.8% (46 cases) after medical treatment. The total abortion rate was 16.4%. Clinical evidence of endotoxaemia was, except for 1 mare, present in all the aborting mares after colic treatment. Anaesthesia did not appear to be a prob...
Hicks GR, Fraser NS, Bertin FR.Although there are many hormonal changes associated with reproduction, the effects of ovulation and early pregnancy on adrenocorticotropic hormone (ACTH) and insulin concentrations are poorly described. We hypothesise that both ovulation and early pregnancy will alter ACTH and insulin concentrations in healthy mares. Eighteen mares showing no clinical signs suggestive of, or laboratory findings consistent with, pituitary pars intermedia dysfunction PPID and insulin dysregulation (ID) are enrolled. ACTH, cortisol, insulin and glucose concentrations are measured over their peri-ovulatory period,...
Ing NH, Konganti K, Ghaffari N, Johnson CD, Forrest DW, Love CC, Varner DD.It is not unusual for stallions to have fertility problems. For many, artificial insemination with more dense spermatozoa (isolated by density gradient centrifugation) results in greater pregnancy rates compared with the rates when using unfractionated spermatozoa. RNAs in spermatozoa delivered to the oocyte at conception are required for embryo development. Novel molecular assays of spermatozoa that reflect function are needed to predict the fertility of stallions. To describe and compare the RNA populations in more dense and less dense spermatozoa from stallions. Spermatozoa from five stalli...
Hinrichs K, DiGiorgio LM.A technique was developed in which immature horse oocytes, obtained from slaughterhouse specimens, were transferred to the pre-ovulatory follicle of a mare in vivo, with resulting oocyte maturation, ovulation, fertilization and embryo development. Oocytes were collected from all follicles greater than 3 mm, and were classified as immature, maturing, expanded or denuded. The transfers were performed in the standing, tranquilized mare. The ovary containing the pre-ovulatory follicle was grasped per rectum. A trochar and cannula were placed through the abdominal wall in the flank area, ipsilatera...
Gastal EL, Pastorello M, Godoi DB, Gastal MO.This comparative study between postpartum lactating (PP Lactating) and non-postpartum cycling (N-PP Cycling) mares aimed to characterize reproductive patterns, types and frequencies of follicular waves, corpus luteum and endometrial echotexture dynamics, and the influence of season and body condition. Mares from each group were paired considering the day of parturition of a PP Lactating mare. The partum-ovulation interval (POI) and the postpartum interovulatory interval (PPIOI) were evaluated for PP Lactating mares, and 2 IOIs were evaluated for N-PP Cycling mares. The following observations w...
Holtan DW, Nett TM, Estergreen VL.Peripheral plasma progestagens were quantified by a competitive protein-binding assay throughout pregnancy. The level of progesterone increased significantly between Days 0 and 8 (P less than 0-05) and again between Days 28 and 44 and reached a maximum on Day 64. Subsequently, it fell slowly until about Day 300 and then rose again during the last 30 days before reaching a minimum on the day after foaling. Very low concentrations of 17alpha-hydroxyprogesterone were found except between Days 40 and 120 and during the last 30 days before birth. Two unidentified compounds, one eluting slightly bef...
Evans TJ.During equine gestation, ergopeptine alkaloid exposure is not uncommon, and pregnant mares are particularly sensitive to the endocrine disruptive effects of these compounds on lactogenesis and steroidogenesis. Agalactia, prolonged gestation, abortion, dystocia, and placental and fetal abnormalities are all clinical manifestations of changes in the endocrine milieu induced by the ingestion of ergopeptine alkaloid-contaminated feedstuffs by mares during late gestation. An understanding of the endocrine disruptive effects of gestational exposure to ergopeptine alkaloids is necessary for the diagn...
Lea KM, Smith SR.Central Kentucky horse pastures contain significant populations of tall fescue (Schedonorus arundinacea (Schreb.) Dumort) infected with an endophyte (Epichloë coenophialum (Morgan-Jones and Gams) Bacon and Schardl) known to produce several ergot alkaloids, with ergovaline in the highest concentration. While most classes of horses are not adversely affected by average levels of ergovaline in pastures, late term pregnant mares have a low tolerance to ergovaline and the related ergot alkaloids. Endophyte-infected tall fescue has been known to cause prolonged gestation, thickened placenta, dystoc...
Terqui M, Palmer E.Plasma total (conjugated + unconjugated) oestrogens were measured from Day 0 to 100 of pregnancy and compared with the levels found during the oestrous cycle. From Day 0 to 35 of gestation, the concentrations were similar to those during dioestrus. An increase in total oestrogens between Days 35 and 40 was followed by a plateau of 3 ng/ml between Days 40 and 60 which was slightly higher than preovulatory concentrations. This first increase in total oestrogen level was produced by the ovaries since values were suppressed after ovariectomy; stimulation may be due indirectly to PMSG causing folli...
Lawson EF, Grupen CG, Baker MA, Aitken RJ, Swegen A, Pollard CL, Gibb Z.Lipids are dynamic biological molecules that play key roles in metabolism, inflammation, cell signalling and structure. They are biologically significant in the physiology of conception and reproduction. Many of the mechanisms surrounding equine conception and the early feto-maternal dialogue are yet to be understood at a biochemical level. Recently, lipidomic technologies have advanced considerably and analytical strategies have been enhanced and diversified. Consequently, in-depth lipidomic exploration now has the potential to reveal new lipid biomarkers and biochemical relationships that im...
Langlois B, Blouin C, Chaffaux S.The files for ultrasound diagnosis of gestating mares belonging to the French equine herd recorded for 3 consecutive years were joined with the files for foal birth of these same mares, allowing the statistical analysis of factors of pregnancy loss. For 28 872 positive diagnoses of gestation, 2898 losses were recorded, that is, a global rate of gestation interruption of 9.12%. The etiology of these interruptions is mainly extrinsic: the year and month of insemination, as well as region for climatic reasons. The intrinsic causes that are implicated are breed of the father (heavy breeds except t...
Mari G, Iacono E, Merlo B, Castagnetti C.Diagnosis and management of twin pregnancies in the mare are an ongoing challenge in equine reproduction. Early detection of twin and manual crush of one vesicle are the main steps in the management of twins. Few studies were carried out about the use of transvaginal ultrasound-guided aspiration (TUGA) for reduction of twins in the mare. In this study, the efficiency of TUGA for management of twin pregnancies was investigated. Reduction of unicornuate twins between 16 and 25 days of gestation gave a success rate of 70.0% (14 viable foals/20 twin pregnancies); when reduction was performed after...
Woods J, Rigby S, Brinsko S, Stephens R, Varner D, Blanchard T.Two trials were conducted to investigate the effects of intrauterine infusion of PGE2 and uterine horn insemination on pregnancy rates in mares achieved by breeding with a suboptimal number of normal spermatozoa. Estrus was synchronized and mares were teased daily with a stallion to detect estrus. Mares in estrus were examined by transrectal palpation and ultrasonography to monitor follicular status. On the first day a 35-mm diameter follicle was present, hCG (1500 IU, iv) was administered and the mares were bred the next day. Mares (Trial 1, n = 34; Trial 2, n = 28) were inseminated with 25 m...
Diaz F, Bondiolli K, Paccamonti D, Gentry GT.Pregnancy rates after cryopreservation of large equine blastocyst stage embryos have remained lower than other domesticated livestock species. It is generally accepted that the embryonic capsule is the primary barrier to cryoprotectant entry into the embryo proper and techniques need to be developed to circumvent this obstacle. Therefore, the objective of this study was to develop an efficient Day 8 equine embryo cryopreservation protocol through blastocyst micromanipulation and vitrification. Grade 1 and 2 embryos recovered from mares (n = 15) 8 days after ovulation were used in these experim...
Douglas RH, Ginther OJ.Several experiments indicated that prostaglandin F2alpha (PGF2alpha) has luteolytic and abortifacient properties in mares. A single subcutaneous injection of 1-25 mg PGF2alpha on Day 6 of dioestrus was as effective as 10 mg PGF2alpha in inducing luteolysis. Oestrus and ovulation appeared to be synchronized when a single injection of 1-25 mg PGF2alpha was given on Days 7, 10 or 13 after ovulation but not on Days 1 or 4 after ovulation or on Day 2 of oestrus. Intramuscular administration was as effective as subcutaneous administration and 1-25 mg PGF2alpha was the minimal effective systemic dose...
Hanlon DW, Firth EC.The objective of this study was to investigate the effects of intravaginal progesterone on the reproductive performance of transitional Thoroughbred mares on commercial stud farms. Two hundred twenty-seven (227) non-lactating transitional Thoroughbred mares aged between 4 and 18 y (mean 9.4 ± 3.2 y) located on three stud farms in the Waikato region of New Zealand were used in the study performed during four consecutive breeding seasons (2007-10). Mares were age-matched in pairs and either treated with an intravaginal progesterone releasing device (Cue-Mare, 1.72 g progesterone, 10% w/w) for u...
Lennard SN, Stewart F, Allen WR.Placentation in equids involves two types of trophoblast: a minor invasive component, the chorionic girdle, that gives rise to transient endocrine structures known as endometrial cups, and a major non-invasive component, the allantochorion, that forms the diffuse, microcotyledonary placenta. Growth factors are likely to be important in controlling these complex events at implantation and this study describes the use of in situ hybridization and northern blotting techniques to monitor expression of insulin-like growth factor II (IGF-II) in the fetus and placenta of the horse (Equus caballus), u...
Albrecht BA, Daels PF.The onset of equine chorionic gonadotrophin (eCG) secretion in pregnant mares is associated with an increase in luteal androgen and oestrogen production. The luteal cell type(s) responsible for the increased production of androgens and oestrogens has not been identified in the equine corpus luteum. In this study, we examined the pattern of expression of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), cytochrome P450 17 alpha-hydroxylase/17,20-lyase (P450(17 alpha)) and cytochrome P450 aromatase (P450arom) by immunohistochemistry in equine luteal tissue collected during dioestrus (days 7-10; ...
Blanchar TL, Brinsko SP, Rigby SL.A tendency for deslorelin implants to suppress subsequent follicular growth and delay return to estrus following induced ovulation has been documented in nonlactating mares. To investigate this phenomenon in lactating mares, 22 broodmares in southeast Texas were administered either deslorelin or hCG to induce ovulation in the first postpartum estrus during February and March 2001. Mares were teased daily and examined twice weekly (Tuesdays and Thursdays) by transrectal ultrasonography. When a follicle >35 mm diameter was detected on Tuesday, mares were treated with either 2,500 U hCG admini...
Griffin PG, Ginther OJ.Transrectal ultrasonography was used to quantitate uterine contractile activity during the estrous cycle and early pregnancy in pony mares (nonbred, n = 9; pregnant, n = 16). Continuous 1-min scans of longitudinal sections of the uterine body were videotaped, and uterine activity scores (1=minimal activity, 5=maximal activity) were assigned to each tape segment. There was a tendency (P<0.06) for a main effect of reproductive status (nonbred versus pregnant), a main effect of day (P<0.0001), and a reproductive status by day interaction (P<0.006). Uterine activity scores were higher (P&...
Fanelli D, Beltramo M, Conte G, Cerretini B, Lomet D, Rota A, Aucagne V, Camillo F, Panzani D.Kisspeptins (KPs) are the most potent stimulating neurotransmitters of GnRH release, and consequently KP administration triggers LH and/or FSH release. In small ruminants, KP or its analogs induced an LH surge followed by ovulation in both cyclic and acyclic animals, while in the mare KP only increased LH plasma levels but failed to induce ovulation. This study in jennies compares the endocrinological effects, ovulatory and pregnancy rates of the KP analog C6 and the GnRH analog buserelin acetate. The ovarian activity of nine Amiata jennies was monitored daily by transrectal ultrasound for thr...
Polasek TCM, Kozicki LE, Pedrosa VB, Weiss RR, Bertol MAF, Camargo CE, Talini R.This study aimed to correlate the inflammatory reaction (IR) caused by a progesterone-releasing intravaginal device (P4) with ovarian activity and pregnancy rate (PR) in embryo-recipient anestrus mares (to decrease the spring transitional period). 50 animals were assigned to three groups: GP4 (P4 group; n = 16), GP4OH (P4 + oxytetracycline hydrochloride and hydrocortisone sprayed onto the device; n = 14), and GNP4 (no intravaginal P4; n = 20). The administration protocol for GP4 was: Day 0, 750 mg P4 + ovarian examination by ultrasonography (US) + vaginal sample collection; Day 8, US;...
Nagel C, Melchert M, Aurich C, Aurich J.Equine fetomaternal monitoring is based on endocrine and cardiac parameters which may differ among small, medium-size, and full-size horses. Therefore, Shetland ( = 6), Haflinger ( = 8), and Warmblood pregnancies ( = 9) were studied during late gestation and at foaling. Weight of mares, foals and placenta, plasma progestin and cortisol concentration, heart rate and heart rate variability (HRV) were determined. Foal weight always approximated 10% of mare weight but relative placenta weight was highest in full-size mares ( < 0.05). Progestin ( < 0.001) and cortisol ( < 0.05) concentrati...
