Mares and horses are integral components of equine studies, focusing on the reproductive and behavioral aspects of equine biology. Mares, or adult female horses, play a significant role in breeding programs and are often studied for their reproductive physiology, gestation, and maternal behaviors. Horses, as a broader category, encompass both sexes and all age groups, providing a comprehensive view of equine anatomy, physiology, and behavior. Research in this area often investigates the differences and similarities between mares and other horses in terms of hormonal cycles, reproductive health, and social interactions. This page compiles peer-reviewed studies and scholarly articles that explore the biological and behavioral characteristics of mares and horses, offering insights into their roles in equine science and management.
Canisso IF, Ball BA, Erol E, Claes A, Scoggin KE, McDowell KJ, Williams NM, Dorton AR, Wolfsdorf KE, Squires EL, Troedsson MH.Nocardioform placentitis in horses is poorly understood, and the development of an experimental model would be of help in understanding the pathogenesis of the disease. Objective: To investigate whether (1) intrauterine inoculation of Crossiela equi during the periovulatory period or (2) i.v., oral or intranasopharyngeal inoculation of C. equi during midgestation would result in nocardioform placentitis, and (3) before and after mating endometrial swabs present evidence of nocardioform placentitis-associated organisms (C. equi or Amycolatopsis spp.). Methods: In Study I, mares (n = 20) rec...
Murphy BA, Wagner AL, McGlynn OF, Kharazyan F, Browne JA, Elliott JA.Circadian rhythms are endogenously generated 24-h oscillations that coordinate numerous aspects of mammalian physiology, metabolism and behaviour. The existence of a molecular circadian clock in equine skeletal muscle has previously been demonstrated. This study investigates how the circadian 24-h expression of exercise-relevant genes in skeletal muscle is influenced by a regular exercise regime. Mid-gluteal, percutaneous muscle biopsies were obtained over a 24-h period from six Thoroughbred mares before and after an 8-week exercise programme. Real-time qPCR assays were used to assess the expr...
Alonso A, Baca Castex C, Ferrante A, Pinto M, Castañeira C, Trasorras V, Gambarotta MC, Losinno L, Miragaya M.The aim of this work was to evaluate the use of air-dried spermatozoa for in vitro production of equine embryos and verify if sperm extract activation and in vivo culture improve in vitro embryo production. Cooled spermatozoa (control) and air-dried spermatozoa stored for 2, 14 or 28 days were used for ICSI sperm extract, or ionomycin was used for oocyte activation, and embryos were in vitro or in vivo (in mare's oviduct) cultured for 7 days. With in vitro culture, cleavage rate was higher when activating with sperm extract (P 0.05). Blastocysts were obtained with cooled spermatozoa, and ...
Abreu RA, Weiss RR, Thomaz-Soccol V, Locatelli-Dittrich R, Laskoski LM, Bertol MA, Koch MO, Alban SM, Green KT.Sera from 112 mares from 5 horse-breeding farms was examined for the presence of antibodies to Neospora caninum and Toxoplasma gondii by an indirect fluorescent antibody test (IFAT), as well as from dogs and cattle present on these properties for the presence of antibodies to N. caninum. Among the 112 mares, 35 had a history of reproductive problems in the last breeding season and 77 had no reproductive problems. The rates of seroprevalence of N. caninum in mares with and without a history of reproductive problems were 25.71% and 6.49% and from T. gondii 2.85% and 1.29%, respectively. In dogs ...
Nagel C, Erber R, Ille N, von Lewinski M, Aurich J, Möstl E, Aurich C.External and internal stressors prolong parturition in different species. At parturition, sympathoadrenal activation should be avoided because an increased sympathetic tone may cause uterine atonia via β2-receptors. We hypothesized that at physiological parturition, horses are under parasympathetic dominance, and stress-response mechanisms are not activated during delivery of the foal. To evaluate stress responses, heart rate, heart rate variability, catecholamines, and cortisol were analyzed in mares (n = 17) throughout foaling. Heart rate decreased from 2 hours before (51 ± 1 beats/minute)...
Murase H, Endo Y, Tsuchiya T, Kotoyori Y, Shikichi M, Ito K, Sato F, Nambo Y.It has not been common to perform regular ultrasound examination of the fetus in equine practice, due to the increasing volume of the uterus caused by fetal development. The convex three-dimensional transducer is bulb-shaped and is able to observe wide areas. In addition, its operation is simple, making it easy to create appropriate angles for various indices using a transrectal approach. The aim of this study was to measure Thoroughbred fetal growth indices throughout gestation using a convex transducer and to clarify the detectable period of some indices for clinical use. We demonstrated cha...
Lyle SK.Placentitis is reported to be the cause of 9.8-33.5% of abortions, stillbirths and perinatal losses in horses. Bacterial infections are responsible for 53% of placentitis cases with Streptococcus equi ssp. zooepidemicus being isolated in 28% of these cases. Clinically, mares may have a vaginal discharge, show udder development, lactate prenatally and deliver a premature or dead foal. Major aspects of the pathogenesis of infectious preterm delivery that may require more effective therapeutic targeting are myometrial contraction, immunological aspects of preterm delivery, and the effects of proi...
Allombert J, Vianney A, Laugier C, Petry S, Hébert L.Taylorella equigenitalis is the causative agent of contagious equine metritis, a sexually-transmitted infection of Equidae characterised in infected mares by abundant mucopurulent vaginal discharge and a variable degree of vaginitis, cervicitis or endometritis, usually resulting in temporary infertility. The second species of the Taylorella genus, Taylorella asinigenitalis, is considered non-pathogenic, although mares experimentally infected with this bacterium can develop clinical signs of endometritis. To date, little is understood about the basic molecular virulence and persistence mechanis...
Flores-Flores G, Velázquez-Cantón E, Boeta M, Zarco L.The effects of repeated cloprostenol administration were compared in mares impregnated by horses and mares impregnated by donkeys in order to assess the role of eCG on the development of pregnancy-associated resistance to the luteolytic and abortifacient effects of PGF2α. Eleven mares impregnated by donkey (mule pregnancy) and 9 mares impregnated by horse (horse pregnancy) were used. Six mares with mule pregnancy and four with horse pregnancy were injected with cloprostenol (0.25 mg) when they were between day 65 and day 75 of pregnancy, and the treatment was repeated 48, 72 and 96 h latter...
Stefanetti V, Marenzoni ML, Lepri E, Coletti M, Casagrande Proietti P, Agnetti F, Crotti S, Pitzurra L, Del Sero A, Passamonti F.Ascending infections of equine uterus frequently result in placentitis and abortions; most of these infections are bacterial and are less commonly due to fungi. This report describes an abortion case in an Arab mare due to Candida guilliermondii that was diagnosed via cytological, histological, cultural and biomolecular assays. The histological lesions found were severe necrotizing placentitis associated with fetal pneumonia. To our knowledge this is the first case of C. guilliermondii abortion reported in equine species.
Ferris RA, Frisbie DD, McCue PM.Current treatments for Persistent mating-induced endometritis such as uterine lavage and oxytocin therapy focus on aiding the uterus in removal of inflammatory products, but these treatments do not modulate the inciting inflammatory response. Biological treatments, such as autologous conditioned serum (ACS) and mesenchymal stem cells (MSCs), have been used in human and veterinary medicine for immunomodulation for over 10 years. The objectives of this project were to evaluate the ability of ACS or MSCs to modulate the inflammatory response to spermatozoa after breeding. Two experiments were pe...
Winfield LS, Brooks MB.A 23-year-old Thoroughbred mare was evaluated because of a coagulopathy causing hemoperitoneum, hematomas, and signs of blood loss-induced anemia. Results: The mare had tachycardia, pallor, hypoperfusion, and a large mass in the right flank. The mass was further characterized ultrasonographically as an extensive hematoma in the body wall with associated hemoabdomen. Coagulation testing revealed persistent, specific prolongation of the activated partial thromboplastin time (> 100 seconds; reference interval, 24 to 44 seconds) attributable to severe factor VIII deficiency (12%; reference inte...
Raś A, Rapacz-Leonard A, Raś-Noryńska M, Barański W.Although fetotomy is recommended for all mares when the fetus is dead and difficult to extract, little has been written about fetotomy and heavy draft mares. This lack includes indications for fetotomy in heavy draft mares, differences in treatment and prognosis of heavy mares kept by farmers of low socioeconomic status, and how this procedure affects the mare's further fertility. The literature on mares, in general, also differs on the survival rate of mares that undergo fetotomy, the prevalence of postpartum complications, and further fertility. To answer these questions, we reviewed the me...
Pirrone A, Antonelli C, Mariella J, Castagnetti C.The aim of this study was to verify if changes in blood glucose, creatinine, urea, and fibrinogen concentrations evaluated at birth reflect gross placenta abnormalities, and are useful to identify foals that suffered from placental dysfunction. A total of 92 mares were included in the present study: 68 delivered healthy foals and they were included in group 1; 24 delivered sick foals and they were included in group 2. In group 2, foals' clinical diagnoses included perinatal asphyxia syndrome (PAS; n = 20) and prematurity and/or dysmaturity (n = 4). The proportion of sick foals was greater when...
Decourt C, Caraty A, Briant C, Guillaume D, Lomet D, Chesneau D, Lardic L, Duchamp G, Reigner F, Monget P, Dufourny L, Beltramo M, Dardente H.Kisspeptin has emerged as the most potent gonadotropin-releasing hormone (GnRH) secretagogue and appears to represent the penultimate step in the central control of reproduction. In the sheep, we showed that kisspeptin could be used to manipulate gonadotropin secretion and control ovulation. Prompted by these results, we decided to investigate whether kisspeptin could be used as an ovulation-inducing agent in another photoperiodic domestic mammal, the horse. Equine kisspeptin-10 (eKp10) was administered intravenously as bolus injections or short- to long-term perfusions to Welsh pony mares, ei...
Tuppits U, Orro T, Einarsson S, Kask K, Kavak A.The aim of this study was to investigate the clinical relevance of measuring blood concentrations of serum amyloid A (SAA), haptoglobin (Hp) and fibrinogen (Fib) in horse reproductive management, and changes in response to artificial insemination (AI) with frozen-thawed semen. Standardbred mares (n=18) with different reproductive status (eight healthy mares in first postpartum oestrus, five healthy barren mares and five mares with endometritis) were inseminated with frozen-thawed semen. Endometritis was evaluated during oestrus by bacteriological culture, cytology and presence of ultrasonicall...
Scholtz EL, Krishnan S, Ball BA, Corbin CJ, Moeller BC, Stanley SD, McDowell KJ, Hughes AL, McDonnell DP, Conley AJ.One of the most widely accepted axioms of mammalian reproductive biology is that pregnancy requires the (sole) support of progesterone, acting in large measure through nuclear progesterone receptors (PRs) in uterine and cervical tissues, without which pregnancy cannot be established or maintained. However, mares lack detectable progesterone in the latter half of pregnancy. Instead of progesterone, several (mainly 5α-reduced) pregnanes are elevated and have long been speculated to provide progestational support in lieu of progesterone itself. To the authors' knowledge, evidence for the bioacti...
Thorson JF, Prezotto LD, Cardoso RC, Sharpton SM, Edwards JF, Welsh TH, Riggs PK, Caraty A, Amstalden M, Williams GL.RFamide-related peptide 3 (RFRP3), the mammalian homologue of avian gonadotropin-inhibitory hormone, has been shown to negatively regulate the secretion of LH and may contribute to reproductive seasonality in some species. Herein, we examined the presence and potential role of the RFRP3-signaling system in regulating LH secretion in the mare during the breeding and nonbreeding seasons. Hypothalamic NPVF mRNA (the precursor mRNA for RFRP3) was detected at the level of the dorsomedial nucleus and paraventricular nucleus, but expression did not change with season. A greater number of RFRP3-expres...
Sessions-Bresnahan DR, Carnevale EM.Obesity in many species is associated with reduced fertility and increased risk of metabolic disorders and cardiovascular dysfunction in offspring. Equine metabolic syndrome (EMS) is associated with obesity and characterized by insulin resistance, decreased adiponectin, and elevated insulin, leptin, and pro-inflammatory cytokines. These alterations can potentially disrupt follicular development and impair fertility. We hypothesized that mares with EMS have an altered follicular environment when compared to their normal counterparts, affecting gene regulation for follicle and oocyte maturation....
Fradinho MJ, Correia MJ, Grácio V, Bliebernicht M, Farrim A, Mateus L, Martin-Rosset W, Bessa RJ, Caldeira RM, Ferreira-Dias G.The aim of this study was to investigate the effects of body condition (BC), BC changes, and plasma leptin concentrations on the reproductive performance of Lusitano broodmares on extensive systems. Data from 119 mares (ranging from 4 to 22 years of age) were collected over a period of four consecutive breeding seasons. Each case was considered as one foaled mare bred in 1 year. Body condition changes at conception (ΔBCScon) showed a strong effect on fertility at the first two postpartum estrous cycles and a significant interaction with body condition score at conception (BCScon) was observed...
Kozai K, Hojo T, Tokuyama S, Szóstek AZ, Takahashi M, Sakatani M, Nambo Y, Skarzynski DJ, Okuda K.Regression of the corpus luteum (CL) is characterized by a decay in progesterone (P4) production (functional luteolysis) and disappearance of luteal tissues (structural luteolysis). In mares, structural luteolysis is thought to be caused by apoptosis of luteal cells, but functional luteolysis is poorly understood. 20α-hydroxysteroid dehydrogenase (20α-HSD) catabolizes P4 into its biologically inactive form, 20α-hydroxyprogesterone (20α-OHP). In mares, aldo-keto reductase (AKR) 1C23, which is a member of the AKR superfamily, has 20α-HSD activity. To clarify whether AKR1C23 is associated wi...
Ponthier J, Franck T, Parrilla-Hernandez S, Niesten A, de la Rebiere G, Serteyn D, Deleuze S.Myeloperoxidase (MPO) is a pro-oxidant enzyme associated with decreased motility in thawed equine semen. This study aimed to describe MPO concentration, activity and subunits in raw and thawed semen and to correlate these data with motilities in raw and thawed semen. Semen samples from five stallions were collected four times. Motilities were assessed in raw and thawed semen. MPO assays were performed in raw seminal plasma, raw sperm-rich pellet and thawed semen. Total and active MPO concentrations were, respectively, assayed by enzyme-linked immunosorbent assay and specific immunological extr...
Seabaugh KA, Schumacher J.Many urogenital procedures of the mare are commonly performed with the mare standing. Ovariectomy via colpotomy was described as early as 1903, and the Caslick vulvoplasty was first described in 1937. As knowledge expands and instruments become more specialized, techniques will improve. With the introduction of laparoscopy, clinicians have not only been able to improve the previously described urogenital procedures but also to devise new procedures. This article describes multiple surgeries of the female urogenital tract, all of which can be performed with the mare standing, and describes a va...
Rambags BP, van Boxtel DC, Tharasanit T, Lenstra JA, Colenbrander B, Stout TA.In many mammalian species, reproductive success decreases with maternal age. One proposed contributor to this age-related decrease in fertility is a reduction in the quantity or functionality of mitochondria in oocytes. This study examined whether maternal age or (in vitro maturation). IVM affect the quantity of mitochondria in equine oocytes. Oocytes were collected from the ovaries of slaughtered mares categorized as young (<12 years) or aged (≥12 years) and either denuded and prepared for analysis immediately (not-IVM) or matured in vitro for 30 hours before preparation (IVM). The m...
Parrilla-Hernandez S, Ponthier J, Franck TY, Serteyn DD, Deleuze SC.Intraluminal fluid and excessive abnormal hyperedema are regularly used for the diagnosis of endometritis in the mare, which is routinely confirmed by the presence of neutrophils on endometrial smears. Studies show a relation between neutrophils and myeloperoxidase (MPO), an enzyme contained in and released by neutrophils during degranulation or after cell lysis. This enzyme has been found in many fluids and tissues, and associated with different inflammatory pathologies in the horse. The aims of this study were to assess the presence and concentration of MPO in the equine uterus, and to inves...
Sabbagh M, Danvy S, Ricard A.Genetic parameters and environmental factors were estimated for foaling ease (FE) and stillbirths (SBs) in four breeds of draft horses based on 11 229, 38 877, 35 764 and 13 274 FE and SB scores recorded between 1998 and 2010 for Ardennais (A), Breton (B), Comtois (C) and Percheron (P), respectively. Incidences for the three FE categories were: easy or without help 91.0% (A) to 95.4% (B), difficult 3.4% (B) to 7.1% (A) and intervention of a veterinarian 1.1% (B) to 1.9% (A). The frequency of SB ranged between 5.4% (B) and 9.4% (A). A multiple-trait threshold animal model was used that included...
Schulman M, Becker A, Ganswindt S, Guthrie A, Stout T, Ganswindt A.Validation of a method for the minimally-invasive measurement of physiological stress will help understanding of risk factors that may contribute to stress-associated events including recrudescence of Equid herpesvirus (EHV), which is anecdotally associated with sales consignment of pregnant Thoroughbred mares. In this study we compared two similar groups of late-gestation Thoroughbred broodmares on the same farm: a consigned Sales group (N = 8) and a non-consigned Control group (N = 6). The Sales mares were separated from their paddock companions and grouped prior to their preparation...
Todhunter KH, Cawdell-Smith AJ, Bryden WL, Perkins NR, Begg AP.Pregnant mares were experimentally exposed to whole caterpillar or exoskeleton of the Processionary caterpillar (Ochrogaster lunifer) via gavage. Tissues were collected from resulting abortions and near or full-term pregnancies consisting of 13 aborted fetuses, 3 fetuses from treated euthanized mares, membranes of 5 foals, and organs from 3 foals. Three control membranes and 1 control fetus and membranes were examined. Caterpillar setal fragments were present in the allantochorion of the 3 fetuses from the euthanized mares and 11 of 12 aborted fetuses (92%) embedded in the chorion (villi or st...
Resende HL, Carmo MT, Ramires Neto C, Alvarenga MA.The identification of fetal sex in horses by location of the genital tubercle between 55 and 70 days of pregnancy is hampered by the large amount of allantoic fluid, extensive fetal movements and the extremely long umbilical cord; however, reliable results have been achieved by ultrasonographic evaluation of the fetal gonads at 110-150 days of pregnancy. Objective: The aim of this study was to diagnose the sex of equine fetuses using B-mode and/or colour Doppler transrectal ultrasonography in fetuses of different ages. Methods: Cross-sectional study comparing 2 methods of determining fetal sex...
Kahler A, McGonnell IM, Smart H, Kowalski AA, Smith KC, Wathes DC, de Mestre AM.Early pregnancy loss (EPL) occurs in approximately 8% of equine pregnancies, although the aetiology is mostly unknown and embryonic/fetal morphological abnormalities associated with EPL are not defined. Objective: To compare the morphology of EPL to clinically normal embryos/fetuses and previously described embryonic/fetal developmental milestones. To identify morphological abnormalities associated with equine EPL. Methods: Observational case-control study. Methods: Embryos/fetuses were obtained from clinically normal Thoroughbred and pony pregnancies (n = 11) and following EPL from Thorough...
Panarace M, Pellegrini RO, Basualdo MO, Belé M, Ursino DA, Cisterna R, Desimone G, Rodríguez E, Medina MJ.Flow cytometry sex-sorting technology was developed in 1989. However, it is only the bovine species in which offspring of the desired sex are obtained at a commercial level. The aim of the present work was to evaluate efficiency parameters when using fresh sexed semen in a large-scale equine commercial embryo transfer program. During the 2009, 2010 and 2011 breeding seasons, 938 synchronized cycles were artificially inseminated. One hundred (10.6%) mares failed to ovulate, and for the remaining 838 useable cycles, 887 doses of sexed semen were used, representing 1.06 doses per cycle. In genera...
Scheurer L, Bachofen C, Herteman N, Hilbe M, Wolfer N, Schoster A.This case series describes three cases of equine multinodular pulmonary fibrosis (EMPF) diagnosed at the Clinic for Equine Internal Medicine at the University of Zurich between 2012 and 2017. Current information on etiology and treatment options are presented. Two horses showed mild signs of chronic lower respiratory tract disease and one horse was presented with acute signs of disease including recurrent fever spikes and tachypnea. Diagnosis was achieved by physical examination, radiographic findings, and PCR testing for equine herpesviruses (EHV) of bronchoalveolar lavage (BAL) fluid or lung...
Honnens A, Weisser S, Welter H, Einspanier R, Bollwein H.The objective of this study was to investigate the relationships between uterine perfusion and estrogen, progesterone and the uterine nitric oxide synthase (NOS) system in five trotter mares during the estrous cycle. Color Doppler sonography for measurement of uterine blood flow and collection of blood for determination of plasma estrogen and progesterone concentrations were performed on days 0 (= ovulation), 1, 5, 11 and 15 and daily during estrus (days -1 to -4) of one estrous cycle; endometrial biopsy collection for mRNA expression analysis of NOS and estrogen receptors was performed on day...
Meyers SA, Overstreet JW, Liu IK, Drobnis EZ.Mammalian sperm that have completed capacitation are capable of undergoing the acrosome reaction in response to a number of biological and chemical stimuli. In the present report, we have investigated the ability of progesterone to stimulate acrosome reactions of stallion sperm capacitated in vitro. Motile sperm were selected by a two-layer Percoll gradient centrifugation and were incubated in TALP medium modified by the 1:1 (v/v) addition of TEST-yolk medium for 5 hours at 39 degrees C, under 5% CO2 in humidified air. Sperm incubated in vitro in TALP-TEST medium had a higher percentage of acr...
Klein C, Bruce P, Hammermueller J, Hayes T, Lillie B, Betteridge K.The current study used RNA sequencing to determine transcriptional profiles of equine endometrium collected 14, 22, and 28 days after ovulation from pregnant mares. In addition, the transcriptomes of endometrial samples obtained 20 days after ovulation from pregnant mares, and from non-pregnant mares which displayed and failed to display extended luteal function following the administration of oxytocin, were determined and compared in order to delineate genes whose expressions depend on the presence of the conceptus as opposed to elevated progesterone alone. A mere fifty-five transcripts were ...
Nagaoka K, Nambo Y, Nagamine N, Nagata SI, Tanaka Y, Shinbo H, Tsunoda N, Taniyama H, Watanabe G, Groome NP, Taya K.The relationship between a selective increase in circulating immunoreactive (ir)-inhibin and the time of ovulation was investigated in mares. Concentrations of plasma ir-inhibin were measured every 4 h during the periovulatory period. Inhibin pro-alphaC, a precursor protein of the inhibin alpha-subunit, was also measured. The changes in ir-inhibin and inhibin pro-alphaC in circulation were parallel. Concentrations of both ir-inhibin and inhibin pro-alphaC in the plasma increased at the same time when ovulatory follicles ruptured, and the peak levels of circulating ir-inhibin and inhibin pro-al...
Cawdell-Smith AJ, Todhunter KH, Perkins NR, Bryden WL.Equine amnionitis and fetal loss (EAFL) is an unusual form of abortion in mid- to late-gestation mares, first identified in Australia in 2004. It has been shown that both whole processionary caterpillars (Ochrogaster lunifer) and their shed exoskeletons can induce abortion in mares during midgestation. These abortions exhibited gross pathology and bacteriology results consistent with field cases of EAFL. Objective: To determine whether exposure of mares to the shed exoskeletons of processionary caterpillars can induce abortion in the preplacentation (<35 days' gestation) and early plac...
Kalashnikov VV, Zajcev AM, Atroshchenko MM, Miroshnikov SA, Zavyalov OA, Frolov AN, Skalny AV.The objective of the present study was assessment of gender differences in hair trace element content in English Thoroughbred horses (North Caucasus, Russia) using ICP-DRC-MS and calculation of the reference values. Trace element content in mane hair of 190 stallions and 94 mares (3-7 years old) bred in North Caucasus (Russia) was assessed using inductively coupled plasma mass spectrometry. Mane hair Co, Cr, Mn, Li, Si, and Sr levels in mares exceeded those in stallions by 77%, 63%, 64%, 42%, 39%, and 64%, respectively. Hair Fe and Si content was nearly twofold higher in female horses as comp...
Zavy MT, Vernon MW, Sharp DC, Bazer FW.Comparisons of estrone, 17 beta-estradiol, and plasma progestin concentrations were made in uterine fluid and peripheral blood of nonpregnant and pregnant pony mares. Concentrations of these steroids were also measured within yolk sac fluid from blastocysts on days 12, 14, 16, and 18 of pregnancy to obtain more complete analyses of the uterine environment (uterine fluid plus yolk sac fluid) of early pregnancy. Thirty mares were randomly assigned to six treatment groups (n = 5/group), and uterine fluid and peripheral blood samples were obtained on days 8, 12, 14, 16, 18, and 20 postovulation. A...
Carnevale EM, Metcalf ES.Intracytoplasmic sperm injection (ICSI) is used to produce equine embryos invitro. The speed of embryo development invitro is roughly equivalent to what has been described for embryos produced invivo. Morphological evaluations of ICSI-produced embryos are complicated by the presence of debris and the dark nature of equine embryo cytoplasm. Morulas and early blastocysts produced invitro appear similar to those produced invivo. However, with expansion of the blastocyst, distinct differences are observed compared with uterine embryos. In culture, embryos do not undergo full expansion and thinning...
Smith JE, Barnes AL, Maloney SK.Body temperature can be a useful measure of how well the horse responds to thermal challenges of exercise and environment. Currently there is little information available about how body temperature changes throughout an endurance ride, and no nonsurgical methods to evaluate internal temperature of exercising horses during prolonged periods and during long distances. Objective: To develop and test a nonsurgical method, using temperature loggers, of continuously recording internal temperature during exercise and over an extended period. Methods: Loggers were inserted transcervically into the ute...
Murray MJ, Mahaffey EA.Specimens of grossly normal gastric stratified squamous epithelial mucosa adjacent to the margo plicatus on the right side and along the greater curvature were obtained from 7 foetuses, 10 term foals and 12 foals 2-35 days old. Gastric squamous epithelium from the foetuses changed markedly during gestation. At 150-270 days, the epithelium was 8-10 cells thick, with a single layer of basal cells. Epithelial cells were polyhedral and had abundant clear or slightly stained cytoplasm. In the 300-day foetus the basal layer was thicker, epithelial cells were polyhedral, and there was a flattened 1 c...
Sedrish SA, McClure JR, Pinto C, Oliver J, Burba DJ.A 12-year-old Morgan mare was examined because of stallion-like behavior of 45 days' duration. Palpation per rectum and transrectal ultrasonographic examination revealed a large left ovary with multiple cystic areas and crepitus. A granulosa-theca cell tumor was suspected. During hospitalization for further evaluation of the affected ovary, the mare developed signs of abdominal pain. Exploratory surgery revealed a large left ovary, which was black with a necrotic and friable surface, and a 720 degrees clock-wise torsion of the ovarian pedicle. Torsion was corrected, and oophorectomy was perfor...
Haines GR, Brown MP, Gronwall RR, Merritt KA, Baltzley LK.Pharmacokinetics and distribution of orbifloxacin into body fluids and endometrium was studied in 6 mares after intragastric (IG) administration at a single dose rate of 7.5 mg/kg body weight. Orbifloxacin concentrations were serially measured in serum, synovial fluid, peritoneal fluid, urine, cerebrospinal fluid, and endometrial tissues over 24 hours. Minimum inhibitory concentrations of orbifloxacin were determined for 120 equine pathogens over an 11-month period. The mean peak serum concentration (Cmax) was 2.41+/-0.30 microg/mL at 1.5 hours after administration and decreased to 0.17+/-0.01...
Abraham M, Bauquier J.The peripartum period is critical in equine medicine for maintaining healthy mares, and ensuring the delivery of healthy neonatal foals. The field of perinatal mortality in horses is continuously evolving, with several advances being recently made in causes of perinatal fetal and foal loss. This review details the main causes of perinatal loss in horses, through late pregnancy, parturition and the neonatal period. Recent advances in identification of infectious organisms and indicators of survival in neonatal foals will be discussed. Continued advances in reproductive and neonatal medicine wil...
Welsch U, Schumacher U, Buchheim W, Schinko I, Jenness P, Patton S.A specific secretory product of the lactating mammary gland are triglyceride fat globules which are enveloped by a very complex membrane, the milk fat globule membrane (MFGM). In different mammalian species (man, rhesus monkey, horse, goat, sheep, cow, grey seal, camel, alpaka) the glycoproteins of this membrane have been analyzed by gel electrophoresis, Western blotting and lectin histochemistry. A remarkable intra- and interspecific variability of these glycoproteins has been detected pointing to so far unknown physiological adaptions, which may play a role in the intestine of the new born. ...
Faur YC, Weisburd MH, Wilson ME.NYC medium supplemented with cow blood (NYC-C) and sheep blood (NYC-S) were tested for the growth of N. gonorrhoeae and urogenital mycoplasma in comparison with standard NYC medium which contains horse blood. In situations where horse blood is not available, cow blood could be substituted in NYC standard medium, whereas the use of sheep blood was found unsuitable.
Spicer LJ, Santiago CA, Davidson TR, Bridges TS, Chamberlain CS.The objective of the present study was to evaluate changes in concentrations of free insulin-like growth factor (IGF)-I in follicular fluid (FFL) during follicle development in the mare. Mares (n = 14) were classified as either in the follicular phase (n = 8) or luteal phase (n = 6). Follicles (n = 92) were categorized as small (6-15 mm; n = 54), medium (16-25 mm; n = 23) or large (>25 mm; n = 15) and FFL was collected. Free IGF-I levels in FFL in large follicles of follicular phase mares were greater (P < 0.05) than in large follicles of luteal phase mares and small or medium follicles ...
Watson ED, Thomson SR.The density and distribution of MHC Class II positive cells and subpopulations of lymphocytes were studied in the endometrium of genitally normal mares and mares susceptible to endometritis. In genitally normal mares, more MHC Class II positive cells were present in the epithelium and stratum compactum during oestrus than dioestrus. Significantly more CD4+ and CD8+ lymphocytes were present in the stratum compactum than in the stratum spongiosum. CD4+ lymphocytes were present in greater numbers than CD8+ lymphocytes in the stratum compactum but approximately equal numbers were present in the st...
Donovan CE, Hazzard T, Schmidt A, LeMieux J, Hathaway F, Kutzler MA.We investigated the effect of immunization against gonadotropin releasing hormone (GnRH) using a commercial canine GnRH vaccine on estrus suppression and unwanted estrous behavior in mares. In experiment 1, mares were immunized (n = 6) twice with vaccine (5 mL) given intramuscularly 4 weeks apart or received a control diluent (n = 5). Transrectal ultrasonographic examination of the reproductive tracts was performed three days a week for 40 weeks after initial vaccination. Blood samples were collected weekly for GnRH antibody titer and progesterone concentration determination. In experiment 2, ...
Teixeira-Soares CM, Viana AGA, Ribeiro IM, Silva KDP, Sancler-Silva YFR, Machado-Neves M.Endometritis is a relevant cause of subfertility in mares. However, the accurate diagnosis, essential for effective treatment, can be difficult due to the variability of results and interpretations resulting from different examination methods and sample collection techniques. The present work compared gynecological evaluation methods and sample collection techniques to diagnose endometritis in subfertile mares. Forty animals with a history of subfertility were selected for gynecological evaluation using clinical methodologies, such as perineal conformation, transrectal palpation and ultrasonog...
Stewart F, Charleston B, Crossett B, Barker PJ, Allen WR.An apparently unique protein produced in large quantities by the endometrium of the mare which adheres to, or is incorporated into, the acellular capsule that surrounds the equine conceptus in early pregnancy, has been characterized and partially sequenced. It has a molecular mass of approximately 18 kDa on SDS-PAGE gels and is nonglycosylated as assessed by a sensitive carbohydrate detection kit. Comparison of its first 24 amino-terminal amino acids with all entries in the databases failed to show any significant identity with any other protein sequence. Secretion of the protein appears to be...
Guillaume D, Palmer E.Two experiments tested the hypothesis that exogenous melatonin (12 mg) given 4 h before dusk (evening melatonin), or near dawn (morning melatonin), would mimic a prolongation of the night and suppress stimulation of the ovaries induced by long days. Experiment 1 consisted of a non-stimulated control group, a control group stimulated by 14.5 h of light, a treated group stimulated with 14.5 h of light plus evening melatonin, a control group given 17.5 h of light and a treatment group given 17.5 h of light plus morning melatonin. The mean (+/- s.e.m.) intervals from the start of treatment to the ...
Jeffcott LB, Rossdale PD.The position, posture and presentation of the fetus were studied by serial radiography of the abdomen in 18 crossbred Pony mares near term and during first- and second-stage labour. In 3 mares the fetal position was assessed before and after induction of parturition with the synthetic prostaglandin, fluprostenol. In late gestation and up to the time of first-stage labour the fetus lay in ventral position with the forelimbs and poll flexed or partly flexed. At this time fetal movements were confined to flexion and extension of neck and forelimbs, but at parturition the head and limbs gradually ...
Wynn MAA, Ball BA, May J, Esteller-Vico A, Canisso I, Squires E, Troedsson M.The objectives of this study were to compare via liquid chromatography-tandem mass spectrometry (LC-MS/MS) progesterone (P4), 5α-dihydroprogesterone (DHP), allopregnanolone, 3β-hydroxy-5α-pregnan-20-one (3β5P), 20α-hydroxy-5α-pregnan-3-one (20α5P), 5α-pregnan-3β,20α-diol (βα-diol), and 5α-pregnan-3β,20β-diol (ββ-diol) concentrations in plasma of mares with experimentally-induced, ascending placentitis compared to gestationally age-matched control mares. Placentitis was induced via intracervical inoculation of Streptococcus equi spp. zooepidemicus between 260 and 280 days of ge...
Neild DM, Chaves MG, Flores M, Miragaya MH, Gonzalez E, Agüero A.The hypo-osmotic test has been used successfully on equine semen and was considered to be a simple and accessible method which could be a useful addition to routine equine semen analysis. It was therefore of interest to determine whether the hypo-osmotic test is significantly correlated to proposed criteria of fertility. The stallions were divided into two groups on the basis of threshold levels of fertility. A significant difference (P<0.05) was found between the two groups for the following parameters: progressive motility, morphologically normal spermatozoa, percentage of swelling with t...
Hanlon DW, Stevenson M, Evans MJ, Firth EC.To describe the reproductive performance of a population of Thoroughbred mares on stud farms in the Waikato region of New Zealand. Methods: A prospective cohort study was performed involving five stud farms in the Waikato region of New Zealand during three consecutive breeding seasons (2006-2008). A total of 1,482 individual mares contributed 2007 mare years and 3,402 oestrous cycles over the three breeding seasons. Mares were served by 87 individual stallions. Results: The mean first-cycle pregnancy rate (FCPR) was 53.6%, the end-of-season pregnancy rate (SPR) was 85.3% and the foaling rate w...
Tongu EAO, Segabinazzi LGTM, Alvarenga ML, Monteiro A, Papa FO, Alvarenga MA.This study aimed to evaluate the effects of mesenchymal stem cell-conditioned medium (MSC-CM) on sperm parameters, intrauterine polymorphonuclear neutrophils (PMN), intrauterine fluid accumulation (IUF), and fertility in mares. In experiment 1, two ejaculates from ten stallions were extended to 50 million sperm/mL using a milk-based extender. Thereafter, 20 mL of extended semen was added of MSC-CM as follows: 0, 5, 10, 15, and 20 mL. Sperm kinetics and plasma membrane integrity were evaluated immediately after dilution (T0) and 2 h post-incubation at 37 °C (T2). In experiment 2, mares cha...
Pinna A, Martins G, Hamond C, Medeiros MA, de Souza GN, Lilenbaum W.The objective was to investigate potential differences between two Leptospira serovars, host-adapted (Bratislava) and incidental (Copenhageni), in causing reproductive disorders in mares. From August 2009 to March 2011, 608 adult recipient mares from eight studs located in the state of Rio de Janeiro, Brazil, were screened for leptospirosis. These mares were 3-8 years of age, of various breeds, and were managed in a semiextensive system (embryo transfer centres). According to the reproductive history of these mares, the studs were categorised as Group A (357 mares: high prevalence of reprodu...
