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.
Leisinger CA, Medina V, Markle ML, Paccamonti DL, Pinto CRF.A novel in vivo model utilizing serial administrations of PGF2α to induce aluteal cycles in the mare was used to evaluate the effects of progesterone-deprivation on the morphology of in vivo preimplantation embryos. We hypothesized that equine embryos produced during induced aluteal cycles (AL) would be developmentally affected, characterized by earlier embryo stage at collection, smaller embryo diameter, and lower quality grade, compared with those collected on the same day post-ovulation from control cycles during diestrus (high progesterone; > 4 ng/mL). Seven cyclic mares with a median ...
Ortiz-Escribano N, Bogado Pascottini O, Woelders H, Vandenberghe L, De Schauwer C, Govaere J, Van den Abbeel E, Vullers T, Ververs C, Roels K....The success rate for vitrification of immature equine oocytes is low. Although vitrified-warmed oocytes are able to mature, further embryonic development appears to be compromised. Objective: The aim of this study was to compare two vitrification protocols, and to examine the effect of the number of layers of cumulus cells surrounding the oocyte during vitrification of immature equine oocytes. Methods: Experimental in vitro and in vivo trials. Methods: Immature equine oocytes were vitrified after a short exposure to high concentrations of cryoprotective agents (CPAs), or a long exposure to l...
Takagi M, Uno S, Kokushi E, Sato F, Wijayagunawardane M, Fink-Gremmels J.Mycotoxins may affect animal health, including reproduction. Little is known about the clinical relevance of exposure of horses to contaminated feed. This study aimed at (i) monitoring the levels of the mycotoxins zearalenone (ZEN), with its metabolites α- and β-zearalenol (α- and β-ZOL), and sterigmatocystin (STC) in urine samples from thoroughbred mares in Japan and (ii) relating these findings to the potential effects on reproductive efficacy of breeding mares. Sixty-three urine samples of breeding mares from 59 breeding farms were used. Urine samples and reproductive records were colle...
Ferrer MS, Palomares R.The potential for life-threatening complications of metritis requires prompt initiation of antimicrobial treatment, often before microbiological test results are reported. However, published studies to guide first-line antibiotic selection are scarce. Objective: To report the most frequent bacterial species, antimicrobial susceptibility and prevalence of multidrug resistance (MDR) in cases of equine metritis. Methods: Retrospective analysis of uterine bacterial culture and antimicrobial susceptibility test (AST) results from mares with metritis. Methods: Data from uterine culture and AST from ...
Ishak GM, Bashir ST, Gastal MO, Gastal EL.Color Doppler ultrasonography was used to study the temporal relationships between pre-ovulatory follicle (POF) and corpus luteum (CL) diameter and blood flow, with systemic progesterone (P4) concentration during two transitional ovulatory seasons in mares. Variables of POF and CL/P4 were evaluated for 6days before and 17days after ovulation, respectively. Evaluations were performed during two consecutive estrous cycles in spring and fall seasons, and during the last estrous cycle of the season. There were significant correlations among POF and CL variables, and P4 concentration that ranged fr...
Leahy ER, Holcombe SJ, Hackett ES, Scoggin CF, Embertson RM.Limited data exist describing broodmare longevity and reproductive efficiency after surgical correction of ≥360 degree large colon volvulus (° LCV). Objective: Compare career duration and foals delivered for broodmares before and after ≥360° LCV surgery. Methods: Retrospective case series. Methods: Broodmares registered with The Jockey Club that had surgical correction of ≥360° LCV and survived to hospital discharge at Rood and Riddle Equine Hospital from 1 January 2000 to 31 December 2015 were included. Information was collected from the hospital's medical data base and The Jockey Cl...
Krakowski L, Bartoszek P, Krakowska I, Olcha P, Piech T, Stachurska A, Brodzki P.The aim of the study was to evaluate physiological changes in hematological and biochemical parameters in mares in perinatal period. Blood samples were collected from 24 pregnant Polish Konik breed mares which were divided into two groups. The first group (Group - I, n=12) comprised mares living in the wild, in the reserve. The second group (Group - II, n=12) consisted of mares kept in stables. The blood was collected 2 weeks prior to the parturition, then 24 hours after the delivery, and then at the 7th and 21st day after foaling. When comparing the two groups before the parturition, no signi...
Cuervo-Arango J, Claes AN, Ruijter-Villani M, Stout TA.Previous surveys reported a positive association between the length of the follicular phase and subsequent fertility in embryo transfer donor and Thoroughbred mares. However, it is unclear whether a longer oestrus positively influences fertilisation and oviductal development (oocyte quality, oviductal environment), or uterine receptivity and survival of the embryo in the uterus. Objective: To determine the effect of length of oestrus (characterised by duration of endometrial oedema) on likelihood of pregnancy and early embryo loss (EEL) in recipient mares after embryo transfer (ET). Methods: R...
Barua S, Macedo A, Kolb DS, Wynne-Edwards KE, Klein C.Milk-fat globule epidermal growth factor (EGF) 8 protein (MFGE8), also known as lactadherin, promotes cell adhesion in an Arg-Gly-Asp (RGD)-dependent modus via integrins. In the present study, the expression of MFGE8 was examined in equine endometrium during oestrus and at Days 12 and 16 after ovulation in pregnant and non-pregnant mares and in mares during the 5th month of gestation. Results demonstrated that MFGE8 is expressed at the embryo- and fetal-maternal interface in equine pregnancy. In non-pregnant endometrium its expression was upregulated by oestrogen, a finding that was confirmed ...
Marth CD, Firestone SM, Hanlon D, Glenton LY, Browning GF, Young ND, Krekeler N.Persistent mating-induced endometritis (PMIE) severely decreases fertility in horses. The aim of the present study was to evaluate differences between horses susceptible to PMIE and a control group in terms of the expression of selected immune response and effector genes, and the effects of oestrous cycle stage on this expression. Endometrial biopsies from 18 uterine samples of mares in the control group (eight in dioestrus, 10 in oestrus) and 16 PMIE-susceptible mares (four in dioestrus, 12 in oestrus) were analysed by quantitative real-time reverse transcription-polymerase chain reaction. Ge...
Christoffersen M, Troedsson M.A transient uterine inflammation post-breeding is a normal physiological reaction in the mare, and it is believed that the inflammatory response is necessary to eliminate bacteria and excess spermatozoa introduced into the uterine lumen. A tight balance between multiple pro- and anti-inflammatory factors is required for resolving the breeding-induced inflammation within 24-36 hr in the reproductively healthy mare, whereas a subpopulation of mares is susceptible to development of a persistent infection that can interfere with fertility. The aetiology of persistent endometritis can be either ba...
Sinclair CD, Webel SK, Douthit TL, Murray LW, Jager AL, Grieger DM, Kouba JM.The objective of these studies was to investigate the efficacy of an intravaginal triptorelin acetate (TA) gel as an ovulation-inducing agent in mares. In Exp. 1, 24 mares were blocked using a combination of parity and age and randomly assigned to 1 of 3 treatment groups: 5 mL TA gel (TA5), 10 mL TA gel (TA10), or 5 mL vehicle gel only (CON). Following the appearance of a follicle ≥ 25 mm, a blood sample was obtained for measurement of LH from each mare every 24 h until treatment administration. When a follicle ≥ 35 mm was observed, treatments were administered intravaginally. Following tr...
Segabinazzi LG, Friso AM, Correal SB, Crespilho AM, Dell'Aqua JA, Miró J, Papa FO, Alvarenga MA.Persistent mating-induced endometritis (PMIE) results in decreased fertility in horses, thereby causing a significant impact in the horse market. Platelet-rich plasma (PRP), a modulator of the inflammatory response, has been largely used in veterinary medicine. Here, we investigated the effects of PRP on uterine inflammation, conception rate, endometrial polymorphonuclear neutrophil (PMN) migration, and COX-2 protein levels in the endometrial tissue. Thirteen PMIE-susceptible mares were used for artificial insemination (AI). The mares were inseminated with fresh semen in three consecutive cycl...
Swegen A, Grupen CG, Gibb Z, Baker MA, de Ruijter-Villani M, Smith ND, Stout TAE, Aitken RJ.Early pregnancy in the mare is a poorly understood, high risk period during which the embryo communicates its presence to the maternal endometrium. Remarkably, the maternal recognition of pregnancy signal is unknown in the horse. This study aimed to profile the proteins secreted by equine blastocysts into their immediate environment, along with proteins contained in the blastocoel and within the acellular embryo capsule. Embryos were recovered on day 8 after ovulation and cultured for 48 hours. Secretomes of day 9 and day 10 embryos were analyzed by LC-MS/MS and supported by analysis of blast...
Grzeskowiak RM, Barrett EJ, Rodgerson DH.An 11-year-old Thoroughbred mare with colic unresponsive to medical treatment underwent exploratory laparotomy. During surgery the cecum was found entrapped within the epiploic foramen from left to right. The entrapped cecum was reduced through the foramen by gentle traction. After reduction of the cecum, rupture of the portal vein was detected. Loss of a large amount of blood prompted euthanasia during surgery. Une jument Thoroughbred âgée de 11 ans atteinte de coliques ne répondant pas au traitement médical a subi une laparatomie exploratoire. Durant la chirurgie, le cæcum a été trou...
Siemieniuch MJ, Gajos K, Kozdrowski R, Nowak M.Even if mares continue to breed up to an advanced age, in aging mares reproductive failure is quite common. Subclinical endometritis, which occurs more often in aging mares than in younger counterparts, may cause prolongation or shortening of the inter-estrus period or the corpus luteum lifespan. We hypothesized that during subclinical endometritis the secretion of selected arachidonic acid metabolites may differ in aging mares compared to younger females. To verify this thesis, ex vivo organ cultures of endometrium were established with subsequent measurements of concentrations of prostaglan...
Carranza J, Yoong WA, Mateos C, Caño Vergara B, Gómez CL, Macías V.Horse reproduction tends to be seasonal. The main adjusting factor in their original temperate ranges is photoperiod variation, although it is absent in equatorial areas where horses were introduced by European colonizers. Hence, dates of reproduction in these areas may be influenced by factors affecting mares' conditions and the success of foaling. Here we study reproductive timing in Creole horses in Ecuador reared in an extensive production system. We found that foaling peaked in August. Mares' conditions showed one peak in June-July, before the start of the breeding season, and another in ...
Garcia-Muñoz A, Valldecabres-Torres X, Newcombe JR, Cuervo-Arango J, Garcia-Rosello E.The objective of this study was to determine the effect of exogenous progesterone administration at ovulation and during the early development of the CL, on its future sensitivity to a single administration of PGF2a in mares and cows. Horse Retrospective reproductive data from an equine clinic in the UK during three breeding seasons were used. Mares were divided into: control group, cycles with single ovulations; double ovulation group cycles with asynchronous double ovulations; and PRID group: cycles with single ovulations and treatment with intravaginal progesterone device (CIDR) immediately...
Onogi A, Shirai K, Amano T.Because native breeds can serve as genetic resources for adapting to environment changes, their conservation is important for future agroecosystems. Using pedigree analysis, we investigated genetic diversity and inbreeding in Japanese Hokkaido native horses, which have adapted to a cold climate and roughage diet. Genetic diversity was measured as the number of founders and the effective number of founders, ancestors and genomes. All metrics imply a decrease in genetic diversity. A comparison of these metrics suggested that pedigree bottlenecks contributed more than did random gene losses to th...
Haywood L, Spike-Pierce DL, Barr B, Mathys D, Mollenkopf D.Incomplete ossification of the cuboidal bones of the carpus and tarsus in foals has the potential for significant consequences including chronic lameness and decreased athletic ability. Objective: To determine if the degree of ossification of the cuboidal bones is associated with gestational length and if the diagnosis of incomplete ossification is a predictor of performance in Thoroughbred racehorses. Methods: Retrospective cohort study. Methods: The medical records of Thoroughbred foals less than 90 days of age from 1994 to 2011 were examined and records containing tarsal radiographs identif...
Zutz C, Wagener K, Yankova D, Eder S, Möstl E, Drillich M, Rychli K, Wagner M, Strauss J.Estrogenic active compounds are present in a variety of sources and may alter biological functions in vertebrates. Therefore, it is crucial to develop innovative analytical systems that allow us to screen a broad spectrum of matrices and deliver fast and reliable results. We present the adaptation and validation of a fungal biosensor for the detection of estrogen activity in cow derived samples and tested the clinical applicability for pregnancy diagnosis in 140 mares and 120 cows. As biosensor we used a previously engineered genetically modified strain of the filamentous fungus Aspergillus ni...
Campbell MLH, Hampshire D, Hamstead LE, Rose BV, Smith KC, de Mestre AM.Intrauterine infusion of peanut oil at Day 10 post-ovulation has been reported to prolong dioestrus in mares. However, the effects of peanut oil treatment on the endometrium and whether the technique is painful have not been assessed. The objectives of this study were, (i) to determine the effect of intrauterine infusion of peanut oil on endometrial health, (ii) to determine whether use of intrauterine peanut oil is painful and (iii) to confirm that peanut oil causes prolonged dioestrus. Six mares aged 3-12 years old were used in a cross-over design with each mare administered both 1 ml of in...
Gibson C, de Ruijter-Villani M, Stout TAE.Placental imprinted genes appear to be sensitive indicators of an inappropriate pre-implantation environment. This study examined the effects of negative uterine asynchrony after embryo transfer (ET) on early horse embryo development, and yolk-sac membrane expression of DNA methyltransferases (DNMTs) and equine specific placental imprinted genes. Methods: Day 8 embryos were transferred to recipient mares on day 8 (synchronous) or day 3 (asynchronous) after ovulation, and conceptuses were recovered 6 or 11 days later (day 14 or 19 of development). Results: Day 14 conceptuses recovered from an a...
Killisch R, Böttcher D, Theuß T, Edzards H, Martinsson G, Einspanier A, Gottschalk J, Schoon HA.The deep anoestrous phase in winter is part of the anovulatory season in mares and is bordered by the autumn and spring transitional periods (ATP/STP). To define an annual time span for effective prognostic biopsy sampling, the aim of this study was to provide a morphofunctional characterization of the endometrium during ATP and STP. To outline both transitional periods, endometrial specimens were taken in September, October and November (n = 76) as well as February, March and April (n = 184) with the requirement of a detailed clinical documentation. Tissue samples were examined histologic...
Janes JG, Kennedy LA, Garrett KS, Engiles JB.Equine catastrophic skeletal breakdown injury is a serious issue within the racing industry, given the impact on equine and human health. The metacarpo- and metatarso-phalangeal (fetlock) joints are common sites of catastrophic injury. However, lesions involving articular cartilage, subchondral bone, and synovium are commonly identified within the fetlock of the contralateral limb; hence, it is imperative that lesions in both limbs are evaluated and characterized during postmortem examination. Bone and articular cartilage changes typically occur in specific locations, related to cyclic fetlock...
Murase H, Miyazawa M, Harada T, Ozawa M, Sato F, Hada T.The degree of fetal growth restriction has been unclear in equine reproduction. In this study, 2,195 fetuses from 2,137 abortions during 11 seasons were examined to determine the causes of abortion, and fetal size dimensions (crown rump length and body weight) were measured. In total, 900 cases (42.1%) of abortion were identified as caused by viral infection (215, 10.1%), bacterial infection (156, 7.3%), fungal infection (25, 1.2%), circulation failure (406, 19.0%), multiple causes (66, 3.1%), deformity (13, 0.6%), placental abnormality (12, 0.6%), and other causes (7, 0.3%). All viral infecti...
Beythien E, Wulf M, Ille N, Aurich J, Aurich C.In pregnant mares, peripheral insulin antagonism channels glucose preferentially to the foetus. On the other hand, horses reduce their metabolic activity in winter. Taking these aspects of equine pregnancy and metabolism together, we hypothesized that glucose clearance from blood and the insulin response to glucose do not only change throughout gestation but also with season. To test this hypothesis, the glucose and insulin response to an oral glucose test and relative insulin release were analysed in pregnant mares (n=12) and in geldings (n=10) as controls. Animals were tested in June, Septem...
Paulini F, Chaves SB, Rôlo JLJP, Azevedo RB, Lucci CM.Visualization and clear understanding of the ovarian structures are important in determining the stage of oestrus, helping to diagnose several pathologies and supporting advances in reproductive technologies. In this research, computerized microtomography (microCT) was used to explore and characterize the ovarian structure of seven mammalian species. Ovaries of rats, female dog, queens, cows, mares, sows and a female donkey were used. After microCT scanning, the same samples were prepared for histologic evaluation, used here as a validation criterion. It was possible to distinguish regions of ...
Agnew ME, Slack J, Stefanovski D, Linton JK, Sertich PL.Variable gestation length in the mare poses a challenge for determination of fetal readiness for birth. The objectives of this study were to describe sonographic characteristics of the fetal GI tract in the late gestation mare and identify changes that occur with progressing fetal maturity. Based on these characteristics, a grading scale modeled after the existing human and canine scoring system was developed. Weekly sonographic examination of the fetus by one observer beginning 2-3 weeks prior to a calculated due date of 330 days was performed. Fetal assessment included; presence of stomach r...
Onogi A, Shirai K, Amano T.Because native breeds can serve as genetic resources for adapting to environment changes, their conservation is important for future agroecosystems. Using pedigree analysis, we investigated genetic diversity and inbreeding in Japanese Hokkaido native horses, which have adapted to a cold climate and roughage diet. Genetic diversity was measured as the number of founders and the effective number of founders, ancestors and genomes. All metrics imply a decrease in genetic diversity. A comparison of these metrics suggested that pedigree bottlenecks contributed more than did random gene losses to th...
Brown MP, Gronwall R, Castro L.Six healthy adult mares were each given a single IV injection of trimethoprim (TMP)-sulfamethoxazole (SMZ) at a dosage of 2.5 mg of TMP/kg of body weight and 12.5 mg of SMZ/kg. Serum concentrations of each drug were measured serially over a 24-hour period. For TMP, the mean overall elimination rate constant (K) was 0.43/hr and the elimination half-life (t1/2) was 1.9 hours. The apparent volume of distribution (at steady state) was 1.62 L/kg and TMP clearance was 886 ml/hr/kg. For SMZ, K was 0.22/hr and t1/2 was 3.53 hours. The apparent volume of distribution at steady state was 0.33 L/kg and S...
Korosue K, Murase H, Sato F, Ishimaru M, Endo Y, Nambo Y.The purpose of this study was to observe the changes in body temperature before parturition using a wireless temperature monitoring device (WTMD) and to evaluate the usefulness of body temperature measurements using a digital rectal thermometer (DRT) and a microchip transponder thermometry device (MTTD) for predicting parturition in mares. The body temperatures using a WTMD at 0 hr and -1 hr were significantly different from those at the same time on Days 1-5 (P<0.01). The temperature differences between the morning of Day 0 and at -3 hr, -2 hr, -1 hr and 0 hr using the DRT and MTTD showed ...
Pollard CL, Gibb Z, Clulow J, Ruiz A, Sheridan A, Bahrami M, Swegen A, Grupen CG.A deficiency in NAD has previously been linked with increased occurrences of congenital abnormalities and embryonic death in humans and mice. Early embryonic death is a major factor involved in pregnancy loss in mares, and very little is known regarding the NAD requirements for optimum reproductive function in horses. The aim of this study was to determine the effect of supplementing the diet of mares with nicotinic acid (NA) on the composition of NAD metabolites in the blood and follicular fluid. Vehicle alone or NA (3 g per os) were administered to seven mares over a minimum of 3 consecutive...
Persistent post-breeding induced endometritis (PPBIE) is considered a major cause of subfertility in mares. It consists of persistent or delayed uterine inflammation in susceptible mares. There are many options for the treatment of PPBIE, but in this study, a novel approach aimed at preventing the onset of PPBIE was investigated. Stallion semen was supplemented with extracellular vesicles derived from amniotic mesenchymal stromal cells (AMSC-EVs) at the time of insemination to prevent or limit the development of PPBIE. Before use in mares, a dose-response curve was produced to evaluate the eff...
Beelitz P, Göbel E, Gothe R.In this epidemiological study 37 foals and mares were included, which have been coproscopically examined in regular intervals over a period lasting up to 13 months. The animals derived from nine breeding farms. In three of these farms no anthelmintics were used before this investigation, whereas in six farms at least three years before regular prophylactic treatments with anthelmintics have been carried out. This investigation revealed no differences in the species spectrum of endoparasites as well as in the incidence of infections as regards to the breeding farms with and without anthelmintic...
Quinn BA, Hayes MA, Waelchli RO, Kennedy MW, Betteridge KJ.During the third week of pregnancy, the equine conceptus is enclosed within a capsule, the glycan composition of which changes at around day 16 (ovulation = day 0) when the conceptus becomes immobilized (fixed) in the uterine lumen. Our objective was to characterize the process of fixation by identifying changes in major capsule-associated proteins. Individual equine conceptuses (n = 55) were collected transcervically by uterine lavage between days 13.5 and 26.5. Major proteins extracted from capsules were compared with those in fluids from the uterus and yolk sac by SDS-PAGE. Until day 14, a ...
Squires EL, McCue PM.Embryo recovery from single ovulating mares is approximately 50 per cent per estrous cycle. Superovulation could be used to increase embryo recovery and provide extra embryos for embryo freezing. This review addresses some historical approaches to superovulation, as well as examines factors that affect the response of mares to equine FSH. eCG, GnRH and inhibin vaccines have been of limited success in stimulating multiple ovulation. Numerous studies have shown that injection of equine pituitary extract (EPE) will result in three to four ovulations per estrous cycle and two embryos. A purified, ...
Friso AM, Segabinazzi LGTM, Cyrino M, Correal SB, Freitas-Dell'Aqua CP, Teoro do Carmo M, Dell'Aqua JA, Miró J, Papa FO, Alvarenga MA.Non-steroidal anti-inflammatory drugs (NSAIDs) are a therapeutic option for the treatment of inflammation. However, negative effects of non-selective NSAIDs for treatment of mares with endometritis have been described, including delayed uterine clearance and impairment of ovulations. Firocoxib is a specific cyclooxygenase-2 (COX-2) inhibitor and has the ability to act in the uterus of mares. We investigated the effects of firocoxib on ovulation rate, numbers of polymorphonuclear neutrophils (PMNs), and COX-2 protein levels in the endometrial tissue of susceptible mares after insemination. Two ...
Ginther OJ, Gastal MO, Gastal EL, Jacob JC, Beg MA.An ovulatory follicular wave was induced by ablation of follicles > or =6mm and treatment with prostaglandin F2alpha (PGF) on Day 10 (ovulation=Day 0). Follicle and hormone dynamics of the induced waves were compared among three age groups: young (5-6 y, n=14 waves), intermediate (10-14 y, n=16), and old (> or =18, n=15). During the common-growth phase of the induced wave (Days 12-17), diameter of the future ovulatory follicle was not different among ages, but the young group had more (P or =10mm. The number was correlated (r=+0.7; P<0.0001) within mares between consecutive interovula...
Daels PF, Stabenfeldt GH, Hughes JP, Odensvik K, Kindahl H.The role of prostaglandin F2 alpha (PGF2 alpha) in embryonic loss following induced endotoxemia was studied in mares that were 21 to 44 days pregnant. Thirteen pregnant mares were treated with a nonsteroidal anti-inflammatory drug, flunixin meglumine, to inhibit the synthesis of PGF2 alpha caused by Salmonella typhimurium endotoxin given IV. Flunixin meglumine was administered either before injection of the endotoxin (group 1, -10 min; n = 7), or after endotoxin injection into the mares (group 2, 1 hour, n = 3; group 3, 2 hours, n = 3); 12 pregnant mares (group 4) were given only S typhimurium...
Rota A, Sabatini C, Przybył A, Ciaramelli A, Panzani D, Camillo F.To increase sperm motility, several molecules have been tested in mammals. Methylxanthines have shown effects on sperm motility, capacitation, and on in vitro fertilization processes. The aim of the study was to evaluate if the post-thaw addition of caffeine and/or pentoxifylline changes motility parameters of cryopreserved stallion and donkey spermatozoa. Straws derived from 14 horses and 7 donkeys were thawed and diluted in a milk-based extender to obtain the following final concentrations: CTR (control, no additives), CAF 5 (5 mM caffeine), CAF 10 (10 mM caffeine), PTX 5 (5 mM pentoxify...
Watson ED, Barbacini S, Berrocal B, Sheerin O, Marchi V, Zavaglia G, Necchi D.Ninety five mares were inseminated with frozen semen either within 12 h before ovulation or within 8 h after ovulation. The effect of preovulatory versus postovulatory insemination (AI) on the subsequent detection of uterine fluid was studied. The overall pregnancy rate was 43% and this was not significantly influenced by preovulatory or postovulatory insemination. When mares were first examined 12 h after AI, 18 of 52 mares (35%) had accumulated uterine fluid. However, when mares were first examined 18 to 24 h after AI, only 6 of 43 mares (14%) had uterine fluid. Presence of intrauterine flui...
Ginther OJ.Heifers have two or three major follicular waves per interovulatory interval (IOI). In mares and women, the ovulatory wave is the only major wave in most (75%) IOI. The beginning of diameter deviation during follicle selection of the future dominant follicle (DF) is followed by continued growth of DF and decreasing growth of the future subordinate follicles. Diameter deviation in Bos taurus heifers, mares, and women begins when the future DF is a mean of 8.5, 22.5, and 10.5 mm, respectively. Selection of the ovulatory follicle occurs more frequently from right ovary (RO) in heifers and women...
Scarlet D, Malama E, Fischer S, Knutti B, Bollwein H.Persistent breeding-induced endometritis (PBIE) is a major cause of subfertility in horses and the susceptibility is increased by several factors. The aim of this study was to determine the effects of clinical uterine findings and PBIE therapies, respectively, on pregnancy rate in mares. The analysis included records from 220 mares (390 cycles) inseminated at an artificial insemination (AI) center in Switzerland. Gynecological examinations were performed repeatedly before and after AI to determine cervical tone, uterine edema, and intrauterine fluid accumulation. Pregnancy rate was lower (p < ...
McCoy DJ.Both ovaries in a 10-year-old American Saddle Horse mare were determined to be larger than normal. The mare had problems with infertility during the preceding 3 years. Clinical evaluation revealed that the mare was polyuric, polydypsic, hyperinsulinemic, and hyperglycemic, and had reduced tolerance to exogenous glucose. Bilateral granulosa cell tumors were identified on histologic examination of the ovaries. The precise mechanism for the secondary diabetes mellitus was not determined; however, the cause was suspected to be a result of the synthesis and release of a hormonal substance by the tu...
Roberto Da Costa RP, Carvalho H, Agrícola R, Alpoim-Moreira J, Martins C, Ferreira-Dias G.The purpose of this study was to evaluate different parameters of the immune status in the mare, during the follicular and the luteal phases of the oestrous cycle, in two consecutive years. Functional competence of peripheral blood neutrophils, such as chemotaxis, phagocytosis and oxidative burst was assessed under physiological cyclic conditions (Exp. I). In the second year of this study (Exp. II), besides peripheral blood neutrophil phagocytosis and oxidative burst analysis, circulating lymphocyte subsets were also characterized. The reproductive status in a total of 17 adult cycling mares w...
Raisi A, Davoodi F.The purpose of this review is to provide a comprehensive comparison of spermatic cord torsion in domestic animals. Spermatic cord torsion leads to occlusion of testicular blood flow resulting in ischemia and tissue hypoxia. Spermatic cord torsion has been reported in all domestic mammals but dogs and horses are overrepresented. Abdominal pain (colic), anorexia, vomiting, lameness, and stiff gait are the most common clinical signs reported. The condition may be asymptomatic in cases of a low degree of spermatic cord torsion. In dogs, spermatic cord torsion is most commonly reported in undescend...
Velez IC, Arnold C, Jacobson CC, Norris JD, Choi YH, Edwards JF, Hayden SS, Hinrichs K.Transvaginal ultrasound-guided follicle aspiration (TVA) is performed clinically but there is little information available on complications associated with this procedure. Objective: It is possible that TVA is associated with damage to the ovary and may induce peritonitis or peritoneal adhesions. This study was conducted to determine the effect of repeated TVA on mare health and ovarian status. Methods: Thirty-two mares were used for oocyte recovery via repeated TVA over a 3 year period; different mares were used each year. In Year 1, ovarian status was monitored in 11 mares by transrectal pal...
Warnakulasooriya DN, Marth CD, McLeod JA, Hanlon DW, Krekeler N.Retained fetal membranes (RFM) is a common post-partum problem in mares for which the treatment is highly variable. The aim of this study was (i) to investigate the different treatments used by equine practitioners for RFM and (ii) to determine if there is a difference between treatments used by reproductive specialists and general equine practitioners. Information regarding treatment of RFM was sought from veterinary practitioners via a survey and this was compared to recommendations in the current literature. The survey was sent out to equine veterinarians and mixed practitioners with a high...
Zoller D, Lüttgenau J, Steffen S, Bollwein H.Poor uterine perfusion has been proposed as a cause of infertility in mares. The objective of this study was to investigate the effect of isosorbide dinitrate (ISDN), a nitric oxide donor, on uterine and ovarian blood flow resistance during diestrus and early pregnancy in mares. Six Trotter mares, aged 7 to 14 years, were examined daily during the first 11 days of three diestrous periods, and five of those mares were also examined during the first 11 days of two pregnancies. Six mares randomly received a placebo, a low dose (30 mg, ISDN30), or a high dose of ISDN (60 mg, ISDN60) through t...
Gibson C, de Ruijter-Villani M, Stout TAE.Placental imprinted genes appear to be sensitive indicators of an inappropriate pre-implantation environment. This study examined the effects of negative uterine asynchrony after embryo transfer (ET) on early horse embryo development, and yolk-sac membrane expression of DNA methyltransferases (DNMTs) and equine specific placental imprinted genes. Methods: Day 8 embryos were transferred to recipient mares on day 8 (synchronous) or day 3 (asynchronous) after ovulation, and conceptuses were recovered 6 or 11 days later (day 14 or 19 of development). Results: Day 14 conceptuses recovered from an a...
Crandell RA, Mock RE, Lock TF.Bovine herpesvirus 1247 (one dose) was given subcutaneously to five pregnant pony mares between 227 and 319 days of their gestations. There were no adverse clinical reactions, and the virus was not recovered from nasal swabs collected during a 2-week period after vaccination. Four ponies foaled full-term, live, healthy foals. The foal of the fifth mare (No. 1) was found dead, but on the basis of the pathologic and virologic examinations, the virus was not considered to be the cause of the death. At 3 weeks after vaccination, the pregnant pony mares had a 13- to 250-fold increase in serum antib...
Bailey MT, Troedsson MH, Wheato JE.The hormone-producing equine granulosa cell tumor (GCT) may secrete high levels of inhibin. Measurement of inhibin concentrations may be useful in the diagnosis and conformation of mares with GCT. Inhibin may be measured using RIA, which recognizes dimeric alphabetaA-inhibin as well as the monomeric (free) inhibin alpha-subunit, or using a two-site immunoradiometric assay (IRMA) specific for alphabetaA-inhibin. The objective of this study was to examine concurrent relationships among alpha-inhibin (as measured using RIA), alphabetaA-inhibin (as measured using IRMA), and other hormones (testost...
Fedorka CE, Ball BA, Walker OF, Conley AJ, Corbin CJ, Lu KG, Hanneman JM, Troedsson MHT, Adams AA.Progestins are immunomodulatory in a variety of species. In the horse, the most commonly administered synthetic progestin is altrenogest (ALT), but its effect on the immune system of the non-pregnant mare is unknown. Peripheral blood mononuclear cells (PBMCs) from diestrous mares were incubated with varying concentrations of progesterone (P4) or ALT to assess intracellular production of IFNγ and the expression of select cytokines. Additionally, ten mares received either ALT or VEH daily utilizing a switchback design beginning on the day of ovulation and continuing for 7 days. Circulating PBM...
Schulman ML, Becker A, van der Merwe BD, Guthrie AJ, Stout TA.Equine herpesvirus 1 (EHV-1) is one of the most common causes of infectious abortion in mares. Analysing the demography of outbreaks and detailing subsequent reproductive performance of affected mares will assist in the management of future (threatened) epizootics. Objective: To examine the epidemiology and reproductive outcomes of 2 EHV-1 abortion epizootics with very different patterns of morbidity. Methods: Epidemiological and reproductive data were analysed retrospectively following abortion epizootics associated with EHV-1, but initiated via different routes, among unvaccinated mares on 2...
El-Sheikh Ali H, Scoggin K, Linhares Boakari Y, Dini P, Loux S, Fedorka C, Esteller-Vico A, Ball B.Placenta-specific 8 (PLAC8) is one of the placenta-regulatory genes which is highly conserved among eutherian mammals. However, little is known about its expression in equine placenta (chorioallantois; CA and endometrium; EN) during normal and abnormal pregnancy. Therefore, the current study was designed to 1) elucidate the expression of PLAC8 in equine embryonic membranes during the preimplantation period, 2) characterize the expression profile of PLAC8 in equine CA (45d, 4mo, 6mo, 10 mo, 11 mo and postpartum) and EN (14d, 4mo, 6mo, 10 mo, and 11 mo) obtained from pregnant mares (n = 4/...
Marinone AI, Losinno L, Fumuso E, Rodríguez EM, Redolatti C, Cantatore S, Cuervo-Arango J.Advanced maternal age is an important predisposing factor on the reduction of reproductive efficiency. The aim of this study was to evaluate the effect of donor's age on several reproductive parameters in a commercial equine embryo transfer program. Donors were classified into 3 age groups: Group 1=fillies (3 and 4 years old), Group 2=middle age mares (aged 5-10) and Group 3=old mares (aged 13-25). Embryo recovery, multiple ovulation and pregnancy rates and interovulatory intervals were compared amongst age groups. Group 1 (171/244, 70.1%) and Group 2 (774/1081, 71.6%) had a higher (P<0.005) e...
Hedberg Y, Dalin AM, Forsberg M, Lundeheim N, Hoffmann B, Ludwig C, Kindahl H.Ovariectomized mares and mares with inactive ovaries may show signs of estrus. The reason behind this phenomenon is not clear; however, steroid hormones of adrenal origin have been suggested. Moreover, aberrant adrenal hormone production has been implied as a reason why some intact mares may change behavior. In the present study, the effect of ACTH on plasma levels of cortisol, progesterone, androstenedione and testosterone was investigated in intact mares with normal estrous behavior ('controls', n=5) and intact mares that according to their owners showed deviant estrous behavior ('problem' m...
