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.
Malschitzky E, Pimentel AM, Garbade P, Jobim M, Gregory RM, Mattos RC.The objective of this retrospective study was to evaluate the effect of management strategies aiming to improve animal well-being on pregnancy and embryonic death (ED) rates. Breeding records of a cohort of 1206 Thoroughbred mares brought to a stallion station facility, to be bred with the stallions housed there, were evaluated during ten breeding seasons. Mares were blocked according to management strategies in two groups: Stress and Relax. Strategies used to improve animal well-being (Relax group) were as follows: stopping the teasing routine, reducing or eliminating stall confinement, reduc...
Hussein HA, Loose M, Wehrend A.The aim of this study was to evaluate the frequency of puerperal diseases in breeding mares in the first 10 days after birth by analysing patient data. Methods: In a university clinic patient data of 308 breeding mares with puerperal disorders which presented within the first 10 days postpartum were evaluated over a period of 10 years. A distinction was made between diseases which were able to be diagnosed at the first examination and diseases which developed during the patient's stay in the clinic. Results: A total of 21 diseases were diagnosed, with a retained placenta, lochiometra and injur...
da Silveira JC, Winger QA, Bouma GJ, Carnevale EM.Age-related decline in fertility is a consequence of low oocyte number and/or low oocyte competence resulting in pregnancy failure. Transforming growth factor (TGF)-β signalling is a well-studied pathway involved in follicular development and ovulation. Recently, small non-coding RNAs, namely microRNAs (miRNAs), have been demonstrated to regulate several members of this pathway; miRNAs are secreted inside small cell-secreted vesicles called exosomes. The overall goal of the present study was to determine whether altered exosome miRNA content in follicular fluid from old mares is associated wi...
Lin X, Zhou S, Wen L, Davie A, Yao X, Liu W, Zhang Y.Many studies have focused on identifying the genes or single nucleotide polymorphisms associated with the athletic ability of thoroughbreds, but few have considered differences in maternal and paternal heritability of athletic ability. Herein, we report on our association study of career race performances of 675 Australian thoroughbreds with their pedigrees. Racing performance data (prize money per start) were collected from the Bloodhound database. The performance of all horses was categorised as either poor or elite athletic achievement. Then, 675 foals were divided by their parents' perform...
Klein C.Maintenance of pregnancy is dependent on the exchange of signals between the conceptus and the endometrium. The objective of this study was to use next-generation sequencing to determine transcriptome blueprints of the conceptus and endometrium 16 days after ovulation in the horse. There were 7760 and 10 182 genes expressed in the conceptus and endometrium, respectively, of which 7029 were present in both. Genes related to developmental processes were enriched among conceptus-specific transcripts, whereas many endometrium-specific genes had known roles in cell communication, cell adhesion and ...
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...
Johnson GP, Lloyd AT, O'Farrelly C, Meade KG, Fair S.?-defensins are small cationic proteins with potent immunoregulatory and antimicrobial activity. The number of genes encoding these peptides varies significantly between and within species but they have not been extensively characterised in the horse. Here, we describe a systematic search of the Equus caballus genome that identified a cluster of novel ?-defensin genes on Chromosome 22, which is homologous to a cluster on bovine Chromosome 13. Close genomic matches were found for orthologs of 13 of the bovine genes, which were named equine ?-defensins (eBD) 115, eBD116, eBD117, eBD119, eBD120, ...
Arlas TR, Wolf CA, Petrucci BP, Estanislau JF, Gregory RM, Jobim MI, Mattos RC.Corticotherapy is a common treatment in mares susceptible to endometritis. Isoflupredone improves pregnancy rates and affects the protein profile of endometrial fluid in comparison to untreated mares. Dexamethasone decreases postbreeding fluid accumulation and uterine edema; however, its effects on the protein profile of the endometrial fluid have not yet been studied. The aim of the present study was to verify the effect of dexamethasone on the protein profile of endometrial fluid, in the presence or absence of infection, from mares susceptible to persistent postbreeding endometritis. Nine su...
Lemasson A, Remeuf K, Hausberger M.Animal calls are commonly considered indicators of a sudden change in their arousal state. However, reports evidencing associated internal physiological changes are rare. By homology with human "emotional" vocal productions (e.g., laughter and crying), we predicted that animal vocal productions may result in relaxing tenseness or excitement. In this study, 15 stallions equipped with a heart rate monitor were presented a mare at some distance so as to prevent contact, thereby increasing the males' arousal. Stallions' heart rates increased just before whinnying but returned to baseline rates whi...
Rapacz-Leonard A, Raś A, Całka J, Janowski TE.Fetal membrane retention can be a life-threatening condition and its incidence exceeds 50% in heavy draught mares. Although fetal membrane retention is commonly treated with repeated injections of oxytocin, based on the suggestion that it is caused mainly by secondary atony of the uterus, this treatment sometimes fails. This led us to ask if expression of oxytocin receptors differs in mares that retain fetal membranes due to secondary uterine atony. Objective: To determine whether expression of oxytocin receptors in equine placental tissues differs when heavy draught mares expel fetal membrane...
Campbell ML, Sandøe P.Welfare problems related to the way horses are bred, whether by coitus or by the application of artificial reproduction techniques (ARTs), have been given no discrete consideration within the academic literature. This paper reviews the existing knowledge base about welfare issues in horse breeding and identifies areas in which data is lacking. We suggest that all methods of horse breeding are associated with potential welfare problems, but also that the judicious use of ARTs can sometimes help to address those problems. We discuss how negative welfare effects could be identified and limited an...
Burger D, Dolivo G, Marti E, Sieme H, Wedekind C.Odours of vertebrates often contain information about the major histocompatibility complex (MHC), and are used in kin recognition, mate choice or female investment in pregnancy. It is, however, still unclear whether MHC-linked signals can also affect male reproductive strategies. We used horses (Equus caballus) to study this question under experimental conditions. Twelve stallions were individually exposed either to an unfamiliar MHC-similar mare and then to an unfamiliar MHC-dissimilar mare, or vice versa. Each exposure lasted over a period of four weeks. Peripheral blood testosterone levels ...
de Ruijter-Villani M, Deelen C, Stout TA.Leukaemia inhibitory factor (LIF) plays a critical role in blastocyst development and implantation in several species. The present study investigated mRNA and protein expression for LIF, as well as the low-affinity LIF receptor (LIFR) and interleukin-6 signal transducer (IL6ST), in equine endometrium, trophoblast and histotroph during early pregnancy and in the endometrium during the oestrous cycle. Endometrial LIF mRNA expression was upregulated after Day 21 of pregnancy, whereas LIF immunoreactivity increased in the endometrium on Day 28. Expression of LIF mRNA in the yolk sac membrane incre...
Hendriks WK, Colleoni S, Galli C, Paris DB, Colenbrander B, Roelen BA, Stout TA.Advanced maternal age and in vitro embryo production (IVP) predispose to pregnancy loss in horses. We investigated whether mare age and IVP were associated with alterations in mitochondrial (mt) DNA copy number or function that could compromise oocyte and embryo development. Effects of mare age (<12 vs ≥12 years) on mtDNA copy number, ATP content and expression of genes involved in mitochondrial replication (mitochondrial transcription factor (TFAM), mtDNA polymerase γ subunit B (mtPOLB) and mitochondrial single-stranded DNA-binding protein (SSB)), energy production (ATP synthase-couplin...
Gajos K, Kozdrowski R, Nowak M, Siemieniuch MJ.Mares that fail to become pregnant after repeated breeding, without showing typical signs of clinical endometritis, should be suspected of subclinical endometritis (SE). Contact with infectious agents results in altered synthesis and secretion of inflammatory mediators, including cytokines and arachidonic acid metabolites, and disturbs endometrial functional balance. To address the hypothesis that SE affects the immune endocrine status of the equine endometrium, spontaneous secretion of prostaglandin E(2) (PGE(2)), prostaglandin F(2α) (PGF(2α)), 6-keto-PGF(1α )(a metabolite of prostacyclin ...
Woodward EM, Troedsson MH.Transient post breeding endometritis is a normal physiological reaction in the mare, as it is believed that an inflammatory response is necessary for the effective removal of contaminating bacteria and excess spermatozoa introduced into the uterus. While most mares can clear endometritis within a reasonable amount of time, persistent endometritis caused by either bacteria or spermatozoa can threaten the success of a pregnancy. A subpopulation of mares is susceptible to persistent endometritis, and these mares are a concern in equine reproductive medicine. Research has identified several factor...
Karrasch NM, Hubbell JA, Aarnes TK, Bednarski RM, Lerche P.This study compared cardiorespiratory variables in dorsally recumbent horses anesthetized with guaifenesin-ketamine-xylazine and spontaneously breathing 50% or maximal (> 90%) oxygen (O2) concentrations. Twelve healthy mares were randomly assigned to breathe 50% or maximal O2 concentrations. Horses were sedated with xylazine, induced to recumbency with ketamine-diazepam, and anesthesia was maintained with guaifenesin-ketamine-xylazine to effect. Heart rate, arterial blood pressures, respiratory rate, lithium dilution cardiac output (CO), inspired and expired O2 and carbon dioxide partial pr...
Galuppi R, Piva S, Castagnetti C, Iacono E, Tanel S, Pallaver F, Fioravanti ML, Zanoni RG, Tampieri MP, Caffara M.The present study aims to evaluate the prevalence, pattern of spread and risk factors for the transmission of cryptosporidiosis in foals and mares hospitalized in a University Equine Perinatology Unit, where a new subtype family of Cryptosporidium horse genotype was described by Caffara et al. (2013). Mares (36) and foals (37) hospitalized during the 2012 foaling season were included. Multiple sampling from each animal was performed (a total of 305 stool samples were collected). One hundred and eleven environmental samples (gauze swabs) were also collected before and after the breeding season....
Mask TA, Schoenecker KA, Kane AJ, Ransom JI, Bruemmer JE.Immunocontraception with porcine ZP (pZP) can be an effective means of fertility control in feral horses. Previous studies suggest that antibodies produced after pZP vaccination may both inhibit fertilization and cause follicular dysgenesis. Zonastat-H, PZP-22, and SpayVac are three pZP vaccines proposed for use in horses. Although all these vaccines contain the pZP antigen, variations in antigen preparation and vaccine formulation lead to differences in antigenic properties among them. Likewise, despite numerous efficacy and safety studies of Zonastat-H and PZP-22, the contraceptive mechanism...
Ruggeri E, DeLuca KF, Galli C, Lazzari G, DeLuca JG, Carnevale EM.Intracytoplasmic sperm injection (ICSI) is an established method to fertilise equine oocytes, but not all oocytes cleave after ICSI. The aims of the present study were to examine cytoskeleton patterns in oocytes after aging in vitro for 0, 24 or 48h (Experiment 1) and in potential zygotes that failed to cleave after ICSI of oocytes from donors of different ages (Experiment 2). Cytoplasmic multiasters were observed after oocyte aging for 48h (P<0.01). A similar increase in multiasters was observed with an increased interval after ICSI for young mares (9-13 years) but not old (20-25 years) mares...
Santos VG, Bettencourt EM, Ginther OJ.Persistent CL (PCL; n = 10) in mares was studied daily from Day 20 (Day 0 = ovulation) to the ending ovulation. In addition, the 10 days before ovulation at the end of a PCL were compared with the end of an interovulatory interval (IOI; n = 28) during the same months. Concentration of P4, cross-sectional area of CL, and percentage of CL with Doppler signals of blood flow during PCLs remained constant from 64 to about 33 days before the end of luteolysis and then decreased linearly. Concentration of LH between Day 20 and beginning of the ovulatory LH surge increased linearly. A dominant follicl...
Scoggin CF.Advancing age can adversely affect a thoroughbred brood-mare's reproductive efficiency and influence the commercial and athletic potential of her progeny. Causes for the decline in fertility include decreased oocyte and embryo quality, anatomical defects and endometrial degeneration. In addition, evidence exists that as the age of a dam increases, her foals will be at increased risk of morbidity and mortality during the neonatal period. Health issues can have lasting and deleterious effects on surviving foals, including decreased sale value and reduced athletic performance. The purpose of this...
Campos-Chillon F, Farmerie TA, Bouma GJ, Clay CM, Carnevale EM.We hypothesised that advanced mare age is associated with follicle and oocyte gene alterations. The aims of the study were to examine quantitative and temporal differences in mRNA for LH receptor (LHR), amphiregulin (AREG) and epiregulin (EREG) in granulosa cells, phosphodiesterase (PDE) 4D in cumulus cells and PDE3A, G-protein-coupled receptor 3 (GPR3), growth differentiation factor 9 (GDF9), bone morphogenetic protein 15 (BMP15) and mitochondrial (mt) DNA in oocytes. Samples were collected from dominant follicles of Young (3-12 years) and Old (≥20 years) mares at 0, 6, 9 and 12h after admi...
Ginther OJ, Wolf CA, Baldrighi JM, Greene JM.Hourly circulating concentrations of a PGF2α metabolite (PGFM), progesterone (P4), and LH were obtained from a reported project, and concentrations of nitric oxide (NO) metabolites (NOMs; nitrates and nitrites) were determined in eight mares. Unlike the reported project, hormone concentrations were normalized to the peak of the first PGFM pulse of luteolysis (early luteolysis), second PGFM pulse (late luteolysis), and a pulse after luteolysis. The duration of luteolysis was 23.1 ± 1.0 hours, and the peak of the first and second PGFM pulses occurred 6.5 ± 0.9 and 14.8 ± 0.8 hours after the ...
Sessions-Bresnahan DR, Carnevale EM.Age-related changes in follicle paracrine signalling are not defined, and follicular gene transcript abundance could predict oocyte viability. Granulosa cells from preovulatory follicles of mares considered Young (n=12; 4-14 years), Mid-aged (n=9; 15-19 years) and Old (n=14; 20-27 years) were evaluated for transcript abundance related to systemic and follicle-specific pathways. Gene transcript abundance for receptors of insulin, adiponectin and peroxisome proliferating factor-γ were higher or tended to be higher in Mid-aged or Old than Young mares. Transcript abundance for interleukin (IL)-6 ...
Hemberg E, Einarsson S, Kútvölgyi G, Lundeheim N, Bagge E, Båverud V, Jones B, Morrell JM.This study investigated the relationship of the health of the newborn foal and (1) number of polymorphonuclear leukocytes (PMNLs) in the amniotic fluid, (2) bacteria present in the amniotic fluid and the venous umbilical blood, and (3) bacteria present in the uterus of the newly foaled mare. A further aim was to investigate relationships between the bacteriologic findings in the amniotic fluid, umbilical blood, and uterus postpartum. Samples were taken from 50 Standardbred trotter foaling mares from a well-managed stud in Sweden. Parturition was spontaneous in all cases. Length of pregnancy, p...
De Lange V, Chiers K, Lefère L, Cools M, Ververs C, Govaere J.Two unilateral cryptorchid stallions were referred to the clinic because of chronic debilitating condition with emaciation. Rectal examination, and ultrasound and gross examination revealed in both animals an abdominal mass, caudally of the kidney, and multiple nodules spread over the abdomen. Histologic analysis revealed an intra-abdominal malignant seminoma with intraperitoneal and renal metastasis. Interestingly, a seminoma was also present in the descended testis of the draught horse.
Schnabel CL, Steinig P, Schuberth HJ, Koy M, Wagner B, Wittig B, Juhls C, Willenbrock S, Murua Escobar H, Jaehnig P, Feige K, Cavalleri JM.Leukocytes and their functional capacities are used extensively as biomarkers in immunological research. Commonly employed indicators concerning leukocytes are as follows: number, composition in blood, response to discrete stimuli, cytokine release, and morphometric characteristics. In order to employ leukocytes as biomarkers for disease and therapeutic monitoring, physiological variations and influencing factors on the parameters measured have to be considered. The aim of this report was to describe the ranges of selected leukocyte parameters in a sample of healthy horses and to analyse wheth...
Choi YH, Landim-Alvarenga FC, Seidel GE, Squires EL.Experiments were conducted to study effects of macromolecules on stallion sperm capacitation and fertilization as determined by penetration of bovine zona-free and equine partially zona-removed oocytes. Stallion sperm were capacitated in TYH medium (modified Krebs-Ringer bicarbonate) supplemented with either 1 mg/mL of polyvinylalcohol (PVA) or 4 mg/mL of BSA. Capacitation was induced with 8 bromoadenosine cyclic monophosphate (8BrcAMP; 0.5 mM) alone or in combination with 0.1 microM of ionomycin. Intraspecies gametes were co-incubated in TYH/PVA or TYH/BSA for 18 to 20 h. For zona-free bovine...
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 ...
Caltabilota TJ, Earl LR, Thompson DL, Clavier SE, Mitcham PB.Four experiments were conducted 1) to assess the use of glucose responses to insulin injections as a means of estimating insulin sensitivity in horses and 2) to compare the insulin sensitivities of normal horses vs. those displaying hyperleptinemia (HL). In Exp. 1, HL mares and geldings (n = 4 each) and 4 mares and geldings with normal leptin concentrations (NL) were injected intravenously with 20 and 100 mU/kg of BW of bovine insulin on 2 separate occasions in December 2008. In Exp. 2, the experimental protocol was repeated in late April 2009. In Exp. 1, the 20 mU/kg of BW dose of insulin cau...
The Journal of physiologyOctober 6, 2000
Volume 528 Pt 1, Issue Pt 1 209-219 doi: 10.1111/j.1469-7793.2000.00209.x
Fowden AL, Taylor PM, White KL, Forhead AJ.1. Using the Fick principle and tracer methodology, the metabolic rates of chronically catheterized fetal foals (n = 24) were measured at different gestational ages during the second half of gestation and in response to maternal fasting for 36 h in late gestation (n = 4, term approximately 335 days). 2. Absolute rates of umbilical blood flow, fetal glucose utilization and umbilical uptake of oxygen (O2) and glucose increased from mid-gestation to 300 days and then plateauxed until term. The absolute rate of umbilical lactate uptake was significant after, but not before, 280 days of gestation. ...
Kelley DE, Warren LK, Mortensen CJ.L-arginine is an amino acid which can alter pituitary function and increase blood flow to the reproductive tract. The objective was to determine the effect of supplementing 100g of L-arginine on plasma arginine concentrations, follicular dynamics and ovarian and uterine artery blood flow during the estrus that occurs subsequent to foaling. In Experiment 1, mares were fed 100g L-arginine for 1 day during the last 3 weeks of pregnancy and plasma samples taken for every hour for the first 4h and every other hour until 12h.L-arginine supplementation elevated plasma arginine concentrations from 1 t...
Dicken M, Gee EK, Rogers CW, Mayhew IG.To examine the gestation lengths and occurrence of daytime foaling of Standardbred mares foaling outdoors at stud farms in Southland, New Zealand (latitude 45˚S). Methods: Data were collected prospectively at two commercial Standardbred stud farms (Farms A and B), during the 2008/9 and 2009/10 breeding seasons (October to February). For each foaling, the identity of the mare, date and time of foaling, gender of foal, time the mare passed the fetal membranes, time the foal stood, and foaling problems including dystocias, were recorded. The effect of farm, season, gender of foal, month of artif...
Bowling AT, Millon L, Hughes JP.Chromosomal abnormality was detectable in 98 of 180 mares aged 3 years or over with gonadal dysgenesis. The most common abnormality was X monosomy (63,X). The second most common abnormality was a karyotype indistinguishable by G- or C-banding from that of a male horse (64,XY). Two mares demonstrated structural abnormality of one X chromosome [64,X,del(Xp)] which has not previously been reported in horses. One of these foaled a filly with the same karyotype as her dam. Blood typing confirmed parentage of the foal. This is the only example in our experience of fertility in a mare with gonadal dy...
Perkins JD, Windley Z, Dixon PM, Smith M, Barakzai SZ.To evaluate the use of sinoscopy for detection and treatment of ventral conchal sinus (VCS) and/or rostral maxillary sinus (RMS) disease in horses. Methods: Case series Methods: Horses (n=60) with suspected paranasal sinus disease. Methods: Horses were evaluated by sinoscopy through a conchofrontal sinus (CFS) portal with ventral conchal bulla (VCB) fenestration. Other endoscopic sinus approaches and adjunctive diagnostic tests; oral examination, computed tomography, radiography, scintigraphy and endoscopic examination of the upper portion of the respiratory tract were used in some horses. Res...
Hubbell JA, Aarnes TK, Lerche P, Bednarski RM.To evaluate the use of midazolam, ketamine, and xylazine for total IV anesthesia (TIVA) in horses. Methods: 6 healthy Thoroughbred mares. Methods: Horses were sedated with xylazine (1.0 mg/kg, IV). Anesthesia was induced with midazolam (0.1 mg/kg, IV) followed by ketamine (2.2 mg/kg, IV) and was maintained with an IV infusion of midazolam (0.002 mg/kg/min), ketamine (0.03 mg/kg/min), and xylazine (0.016 mg/kg/min). Horses underwent surgical manipulation and injection of the palmar digital nerves; duration of the infusion was 60 minutes. Additional ketamine (0.2 to 0.4 mg/kg, IV) was administer...
Hatzel JN, Bouma GJ, Cleys ER, Bemis LT, Ehrhart EJ, McCue PM.Early pregnancy factor has been identified as a 10-kDa extracellular homolog of heat shock protein 10 (Hsp10). Hsp10 has been detected during early pregnancy in serum of mice, sheep, pigs, horses, cows, and humans by the rosette inhibition test. Hsp10 has also been associated with several neoplastic and autoimmune diseases. The goal of the present study was to determine if Hsp10 could be detected in the early equine embryo through the use of immunohistochemistry and quantitative real-time PCR. Additionally, analysis of systemically harvested peripheral blood mononuclear cells (PBMCs) from both...
Williams GL, Thorson JF, Prezotto LD, Velez IC, Cardoso RC, Amstalden M.Reproductive seasonality in the mare is characterized by a marked decline in adenohypophyseal synthesis and secretion of LH beginning near the autumnal equinox. Thus, ovarian cycles have ceased in most mares by the time of the winter solstice. Endogenous reproductive rhythms in seasonal species are entrained or synchronized as a result of periodic environmental cues. In the horse, this cue is primarily day length. Hence, supplemental lighting schemes have been used managerially for decades to modify the annual timing of reproduction in the mare. Although a full characterization of the cellular...
Alexander SL, Irvine CH.We have developed a non-surgical technique for long-term collection of pituitary venous blood which consists of slightly diluted hypophysial portal blood into which pituitary hormones have been secreted. In these experiments jugular and pituitary venous blood samples were collected from five unmedicated, ambulatory mares at 5-min intervals for 2-6 h on 11 occasions during the 6 days surrounding the ovulatory LH peak. Jugular blood only was collected from another five periovulatory mares without pituitary cannulae. The duration of oestrus was similar in mares with and without pituitary cannulae...
Arango-Sabogal JC, Mouncey R, de Mestre AM, Verheyen K.Up-to-date figures on early losses of Thoroughbreds from the racing industry can inform strategies to improve retention and incentivise traceability of Thoroughbreds during this early life period. Methods: Data on Thoroughbred mares bred in 2013-2014 and training, racing and sales information of their live offspring were analysed. The proportions and 95% confidence intervals (95% CI) of the entire 2014-2015 United Kingdom and Ireland foal crops that entered training, raced, were imported and/or exported between birth and the end of their third year of life, as well as the racing performance of...
Ginther OJ, Gastal EL, Gastal MO, Beg MA.The effect of a single injection of prostaglandin F2alpha (PGF) during mid-diestrus on systemic concentrations of progesterone, LH, FSH, estradiol, and cortisol and on blood flow to the corpus luteum was studied in 10 controls and 10 PGF-treated mares. Blood flow was assessed by estimating the percentage of corpus luteum with color-Doppler signals of blood flow during real-time scanning of the entire structure and by the diameter of the vascular pedicle near its attachment to the ovary. Treatment was done 8 days after ovulation and 0 h was immediately before the treatment. Examinations and col...
Dechant JE, Hendrickson DA.Standing female urogenital endoscopic surgery is facilitated by the more dorsal location of the organs of the female reproduction tract. The most common reason for laparoscopic surgery on the female urogenital system is ovariectomy; however, the technique has been used to diagnose periparturient or reproductive diseases and to perform surgical embryo transfer. Standing surgical approaches avoid the risk and expense of general anesthesia, but these techniques are limited by the temperament and size of the patient and the availability of facilities for restraint. Owner acceptance of laparoscopic...
Thompson DL, DePew CL, Ortiz A, Sticker LS, Rahmanian MS.Three experiments were conducted to determine 1) the relationship between prolactin and growth hormone (GH) secretion in mares and the response to GH-releasing hormone (GHRH), 2) whether plasma GH and prolactin concentrations differed among mares, stallions, and geldings, and 3) whether sexual differences existed after administration of GHRH and acute exercise. In Exp. 1, 10-min blood samples were collected from 12 mares for 8 h, and GHRH (0, 45, 90, or 180 micrograms) was administered at 6 h. In Exp. 2, 15-min blood samples were collected for 4 h from 10 mares, stallions, and geldings. In Exp...
Ishak GMA, Dutra GA, Gastal GDA, Gastal MO, Feugang JM, Gastal EL.The inability to obtain in vivo samples of antral follicle wall layers without removing the ovaries or sacrificing the animals has limited more in-depth studies on folliculogenesis. In this study, a novel ultrasound-guided follicle wall biopsy (FWB) technique was used to obtain in vivo follicle wall layers and follicular fluid samples of growing antral follicles. The expression of proliferative, hormonal, angiogenic, and pro-/antiapoptotic receptors and proteins in the follicular wall among three follicle classes were compared during the spring transitional anovulatory (SAN) and spring ovulato...
Wood SC, Fedde MR.Splenic contraction in racing horses increases the hematocrit (hct), thereby increasing blood viscosity. We tested as to whether racing also affects the elastic properties of blood. Mares and geldings were studied for thus purpose. After racing, there was: (i) an increased erythrocyte count independent of gender and race distance (0.32 to 1.7 km): (ii) an increased mean erythrocyte volume in both sexes; (iii) an increased heterogeneity of RBC size in both sexes; (iv) an increased plasma fibrinogen concentration and erythrocyte sedimentation rate in both sexes; and (v) an increased elastic yiel...
Ishii M, Kobayashi S, Acosta TJ, Miki W, Yamanoi T, Matsui M, Miyake Y, Miyamoto A.The aim of this study was to clarify the relationship between circulating oxytocin (OT) and PGF(2alpha) metabolite (PGFM) in mares at the third stage of labor and placental expulsion time in order to investigate a cause of retained placenta of which the incidence increase in a heavy draft mare. Blood was sampled every 5 min from foaling to expulsion of the placenta in 18 heavy draft mares to evaluate circulating OT and PGFM. The relationships between OT and PGFM concentration and recorded placental expulsion times were investigated. The results were as follows (1) The highest level of OT conce...
Bedford SJ, Kurokawa M, Hinrichs K, Fissore RA.In oocytes from all mammalian species studied to date, fertilization by a spermatozoon induces intracellular calcium ([Ca(2+)](i)) oscillations that are crucial for appropriate oocyte activation and embryonic development. Such patterns are species-specific and have not yet been elucidated in horses; it is also not known whether equine oocytes respond with transient [Ca(2+)](i) oscillations when fertilized or treated with parthenogenetic agents. Therefore, the aims of this study were: (i) to characterize the activity of equine sperm extracts microinjected into mouse oocytes; (ii) to ascertain i...
Allen WR, Kydd JH, Boyle MS, Antczak DF.Transfer of donkey embryos to horse mares provides a useful model of early fetal death. Endometrial cups do not develop in this one type of extraspecific pregnancy and 80% of donkey fetuses are aborted between Days 80 and 100 of gestation in conjunction with abnormal implantation and an intense accumulation of leucocytes in the endometrium of the surrogate mare. Treatment of mares carrying donkey conceptuses with progestagen (allyl trenbolone) or purified horse chorionic gonadotrophin does not prevent abortion. However, passive immunization with serum from mares carrying intraspecific horse fe...
Alpoim-Moreira J, Szóstek-Mioduchowska A, Słyszewska M, Rebordão MR, Skarzynski DJ, Ferreira-Dias G.Endometrosis negatively affects endometrial function and fertility in mares, due to excessive deposition of type I (COL1) and type III (COL3) collagens. The pro-fibrotic transforming growth factor (TGF-β1) induces myofibroblast differentiation, characterized by α-smooth muscle actin (α-SMA) expression, and collagen synthesis. In humans, fibrosis has been linked to epigenetic mechanisms. To the best of our knowledge, this has not been described in mare endometrium. Therefore, this study aimed to investigate the in vitro epigenetic regulation in TGF-β1-treated mare endometrial fibroblasts an...
Koskinen E.In a previous study, times from parturition to the first ovulation were followed in 55 Finnhorse mares on the basis of milk progesterone determinations. Ninety-six per cent of mares had ovulated by day 20 post-partum. If intervals of more than 19 days are excluded from the data, the time from parturition to 1st ovulation was 117 days. However, in cases of foaling before and after the beginning of June the times were 13.0 days and 8.8 days, respectively (p less than 0.001). Long intervals (over 16 days) occurred mainly before 1st May (in 6 out of 7 cases). In a 2nd study, 25 post-partum Finnhor...
Wong PL, Nickel LS, Bowling AT, Steffey EP.Serum samples of 20 horses were evaluated for antibodies against RBC after homologous blood transfusion. Transfusion-associated antibodies against RBC were detected in 10 horses. Antibodies recognizing horse blood group antigens Aa, Ae, Db, and Dc were identified. Antibodies against Aa were found in all samples from Aa-negative horses that were transfused with Aa-positive RBC. Antibodies against Aa persisted for at least 1 year after transfusion. Antibodies against Ae were detected in 7 of 8 horses transfused with Ae-positive RBC. Initial appearance and persistence of antibodies against Ae dif...
White SD, Affolter VK, Schultheiss PC, Ball BA, Wessel MT, Kass P, Molinaro AM, Bannasch DL, Ihrke PJ.A Quarter horse filly bred from two horses affected with HERDA (hereditary equine regional dermal asthenia) was observed clinically and its skin histologically for the 1.5 years of its life. Severe signs of the disease did not manifest until 1.5 years of age, and were not temporally related to saddling. Histological comparison to an age-, breed- and sex-matched control did not show any consistent diagnostic features. Monitoring of the proband substantiated previous reports of (i) the autosomal recessive nature of the disease, (ii) mares affected with HERDA being able to foal without damage to ...
Inácio SV, de Brito RL, Zucatto AS, Coelho WM, de Aquino MC, Aguirre Ade A, Perri SH, Meireles MV, Bresciani KD.The present study aimed to analyze the occurrence of infection by Cryptosporidium spp. in mares and their respective foals. This study was carried out in 11 farms located in the municipalities of Araçatuba, Birigui, Guararapes and Santo Antônio do Aracangua, in the northwest region of the State of Sao Paulo, from November 2010 to March 2011. A total of 98 mares and 98 foals of several breeds were analyzed; among foals, 59 were males and 39 females, aged from three to 330 days. Feces were collected directly from the rectal ampulla, purified and processed according to modified Kinyoun stain. O...
Scofield D, Black J, Wittenburg L, Gustafson D, Ferris R, Hatzel J, Traub-Dargatz J, McCue P.Systemic administration of ceftiofur crystalline free acid (CCFA) may be a potential treatment for infectious endometritis caused by Streptococcus equi ssp. zooepidemicus (S. zooepidemicus) and other susceptible bacterial organisms in the mare. Objective: To determine if i.m. administration of CCFA at the label dose will exceed the minimum inhibitory concentration (MIC) of S. zooepidemicus in the endometrium following single administration and multiple administration protocols. Methods: Experimental pharmacokinetic study. Methods: Three mares (Group 1) were administered a single i.m. dos...
Crawford KL, Finnane A, Greer RM, Barnes TS, Phillips CJC, Woldeyohannes SM, Bishop EL, Perkins NR, Ahern BJ.Musculoskeletal injuries remain a global problem for the Thoroughbred racing industry and there is conflicting evidence regarding the effect of age on the incidence of injuries. The ideal time to commence race training is strongly debated, with limited supporting literature. There is also conflicting evidence regarding the effect of high-speed exercise on musculoskeletal injuries. There is a strong interest in developing training and management strategies to reduce the frequency of injuries. The types of musculoskeletal injuries vary between 2-year-old and older horses, with dorsal metacarpal ...
Kraus M, Physick-Sheard P, Brito LF, Sargolzaei M, Schenkel FS.Admissions of Standardbred racehorses (Std) to the Ontario Veterinary College Teaching Hospital (OVCTH) for treatment of atrial fibrillation (AF) began to increase in the early 1990s. The arrhythmia has been shown to have a modest heritability (h2 ≃ 0.15), with some stallions appearing as sires or sires of mares used in breeding (broodmares) of affected horses more frequently than others. The objective of this study was to determine the marginal genetic contributions of ancestors to cohorts of Std affected with AF and their contemporary control groups, and whether these ancestors contribute ...
Nash DM, Paddison J, Davies Morel MCG, Barnea ER.Persistent mating-induced endometritis (PMIE) is a significant cause of mare infertility hence its treatment would advance the management of susceptible mares. Preimplantation factor (PIF) is secreted by viable embryos, including human, mouse and cattle, and is essential for maternal immune-tolerance without immune-suppression by modulating inflammation. This preliminary study aimed to test whether PIF exerts inflammatory-modulating properties upon equine endometrium challenged with Escherichia coli-derived lipopolysaccharide (LPS) using endometrial explant culture. Follicular (n = 3), lutea...
