Topic:Mares
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.
Changes in the Mare Oviduct Across Different Seasons Throughout the Year. At present, oviductal pathologies and their influence on mare fertility have not been clearly determined. Checking changes throughout the year in the oviductal structure may be relevant to understand the influence on the appearance of problems in oviductal functionality and, thus, the impact on fertility, which is the objective of this work. The oviducts of 56 mares were examined. Their anatomy, permeability, oviductal cellularity and the presence of pathologies were assessed to establish the correlations between the time of the year and each of these parameters. We cannot conclude whether the...
Pharmacokinetics of Topical Administration of Altrenogest in Mares and Implications for Human Health. Altrenogest is a synthetic progestogen widely used in equine reproductive management. Adverse effects to altrenogest have been reported in people with cutaneous exposure reported as the highest exposure pathway. Despite these reports, there has been no quantitative research to determine the capacity for altrenogest to be absorbed through skin. This study aimed to determine if cutaneous application of oral altrenogest results in systemic absorption in mares and to evaluate the influence of application site. A randomized, two-period, two-treatment crossover study was undertaken in eight mares. M...
Repeated intravenous dexamethasone administration causes transient changes in leukocyte parameters in healthy warmblood horses. To determine the effect of repeated IV administration of dexamethasone (0.06 mg/kg, q 24 h, twice) on WBC parameters in healthy adult horses. Unassigned: This prospective, longitudinal study was conducted from October 7 through November 5, 2024. Five warmblood mares received an IV dexamethasone sodium phosphate injection (DMI) at 0 and 24 hours and an IV injection with 0.9% sodium chloride solution at 48 and 72 hours. Blood samples were collected at 0, 6, 12, 24, 30, 36, 48, 72, 96, and 168 hours, and WBC parameters were evaluated using linear mixed-effects models. Unassigned: Leukocyte count,...
Effects of rectal examination on intraocular pressure and behavioral responses in pregnant and non-pregnant mares. Rectal examination is routine in equine reproduction but may trigger acute stress affecting welfare and safety. Intraocular pressure (IOP) responds rapidly to autonomic changes and may capture short-lived stress responses. Objective: To evaluate whether rectal examination acutely affects IOP and behavioral responses in mares, and whether reactions differ by reproductive status. Methods: Twenty Rahvan mares (10 pregnant, 30-40 days' gestation; 10 non-pregnant; 4-7 years) underwent transrectal examination without sedation. IOP was measured bilaterally at six time points: 2 min pre-exam (T1), dur...
Combined Analysis of the Transcriptome and Metabolome at Different Tissue Glycogen Levels in Yili Horses. This study aimed to investigate the relationship between genes and metabolites involved in glycogen metabolism across different tissues of Yili mares using joint transcriptomic and metabolomic analyses. Glycogen content was measured in various tissues (pincer, trapezius, latissimus dorsi, gluteus medius, semitendinosus, external abdominal obliques, liver, and heart) from seven Yili mares. The liver, as the visceral tissue with the highest glycogen content, and the gluteus medius, as the muscle with the highest glycogen content, were selected for transcriptomic sequencing and metabolomic analys...
Characterization of the Endometrial Microbiota of Healthy Mares Across the Estrous Cycle. In the past, bacteria detected in the mare's uterus were generally interpreted as a sign of endometritis, since the uterus was considered a sterile environment. This assumption has been challenged by the introduction of culture-independent molecular techniques, particularly 16S rRNA amplicon sequencing, which have demonstrated that healthy mares harbor an endometrial microbiota. The aim of this study was to characterize the endometrial microbiota of healthy mares and to determine whether microbial composition differs between estrus and diestrus. Endometrial samples were collected from eleven h...
Comparative Evaluation of Follicular Flushing Frequency and Scraping Time During Ovum Pick-Up in Mares: Effects on Oocyte Recovery Rate and Technical Considerations. Transvaginal ultrasound-guided follicular aspiration or ovum pick-up (OPU) has become the standard technique for oocyte collection in mares for intracytoplasmic sperm injection (ICSI). Although repeated follicular flushes and wall scraping are commonly used to improve oocyte recovery rate (ORR), the relative contribution of each remains unclear. This study aimed to compare the effects of multiple flushes versus controlled scraping time on ORR in mares. A controlled trial was conducted in two phases: (1) an ex vivo phase using slaughterhouse ovaries (n = 32), and (2) an in vivo phase in c...
Differential profiles of GH, IGF-1, and fructosamine in follicular fluid and plasma of cyclic mares. Growth hormone (GH) influences follicular development mainly by stimulating insulin-like growth factor 1 (IGF-1), which acts systemically and locally within the ovary. However, the metabolic profile of follicular fluid (FF) in mares, particularly markers such as fructosamine (FRUCT), an indicator of glucose metabolism, remains poorly characterized. This study aimed to evaluate GH, IGF-1, and FRUCT concentrations in plasma and FF and their variation across follicle sizes. Sixty ovaries were collected during the breeding season from 30 clinically normal mares raised for meat production. Blood sa...
Nicotinic acid treatment improves the developmental potential of equine oocytes for cloned embryo production. Nicotinic acid (NA) treatment during in vitro maturation (IVM) has been shown to elevate nicotinamide adenine dinucleotide (NAD) levels and improve oocyte developmental competence. Suboptimal equine oocyte IVM systems currently limit the efficiency of viable embryo in vitro production. This study evaluated NA supplementation during IVM for cloned equine embryo production, using oocytes from abattoir-sourced ovaries and live mares via ovum pick-up (OPU). Abattoir-derived oocytes (n = 694) were treated without or with 50 or 200 μM NA during the 18 h holding period (Pre-IVM). Next, OPU-deriv...
Amniotic Mesenchymal Stromal/Stem Cell-Derived Extracellular Vesicles for Equine Chronic Degenerative Endometritis Treatment. Equine chronic degenerative endometritis (CDE) is a progressive process characterized by endometrial fibrosis that could be responsible for alterations of uterine environment and foetal-maternal communication. Objective: The aim of this study was to try to restore this communication by intrauterine administrations of amniotic cell-derived extracellular vesicles (AMC-EVs) in a case series. Methods: Twelve mares were selected on the basis of their reproductive history of early embryonic loss or abortion and clinical suspicion of CDE subsequently verified with histopathological examination of end...
Pharmacopuncture with low-dose dexmedetomidine and saline aquapuncture at acupoint Governing Vessel 24 provides sedation in healthy adult horses. To evaluate sedation in horses following pharmacopuncture with dexmedetomidine at acupoint Governing Vessel 24 (GV-24) compared to aquapuncture at GV-24 or an equivalent dose of dexmedetomidine administered via IV or SC routes. Unassigned: 10 adult mares received 4 treatments in a blinded, randomized, crossover design: (1) dexmedetomidine administered at GV-24 (DexmedGV24; 1 μg/kg); (2) saline administered at GV-24 (SalineGV24; 1.5 mL); (3) dexmedetomidine administered SC on the lateral neck (DexmedSC; 1 μg/kg); or (4) dexmedetomidine administered IV (DexmedIV; 1 μg/kg). Sedation scores (fa...
Analysis of the antitrypsin activity and immunoglobulin G concentration in equine colostrum and milk. Immunoglobulins ingested via colostrum must remain intact to be absorbed by the neonate. Equine colostrum contains antitrypsin activity, which likely protects these proteins from proteolysis in the gastrointestinal tract. Objective: To quantify antitrypsin activity in equine colostrum and milk, describe its temporal changes during the first five days after parturition, compare actitvity between left and right mammary glands, evaluate differences between nulliparous and pluriparous mares, and examine associations with immunoglobulin G (IgG) concentrations and mare age. Methods: This retrospecti...
Diagnosis of Equine Genital Leptospirosis (EGL) in mares with poor reproductive performance. Leptospirosis is a zoonotic disease caused by spirochetes of the genus Leptospira. Equine genital leptospirosis (EGL) has been described as a chronic and silent syndrome, presenting reproductive alterations such as abortion, stillbirth, placentitis, embryonic loss, repeat breeding syndrome, and subfertility. This study aimed to investigate the genital Leptospira infection in naturally infected mares with poor reproductive performance, as well as to genetically characterize the agents. A total of 41 mares with a history of poor reproductive performance were selected. Sera were collected for ser...
GnRH Administration Increases Synchronisation of Ovulation in Mares. The objective of this study was to evaluate the effects of exogenous GnRH administration at the beginning of estrus synchronisation in mares during the spring transitional period. Estrus was synchronised using a progesterone releasing intravaginal device (PRID). The PRID was left in the vagina for 10 days, followed by an injection of 0.4 mg of cloprostenol at PRID removal. The GnRH group (n = 32) was subjected to intramuscular administration of 100 μg of the GnRH agonist triptorelin at PRID insertion, while the control group (n = 32) received 1 mL of sterile physiological sali...
Infertility in an American Quarter Horse mare with cervical duplication. Cervical duplication is a disorder of sexual development (DSD) that may be present in the absence of chromosomal aberrations. It is a rare cause of infertility in mares and is attributed to the failure of the Müllerian ducts to fuse properly, leading to the persistence of the median walls along the whole length of the cervix. This case report involves a 13-year-old American Quarter Horse mare with cervical duplication. Prior to this diagnostic, the mare was bred multiple times, but pregnancy was not achieved. The mare presented for a breeding soundness evaluation. During the examination an ab...
The Effect of Seasonal Changes in Non-Structural Carbohydrates in Pasture on the Metabolic Profile of Horses with Laminitis. This study aimed to examine the seasonal dynamics of non-structural carbohydrates in pasture and their relationship to metabolic indicators in horses with a history of laminitis. Thirty Hucul mares were divided into a laminitis group (LG, = 15) and a control group (CG, = 15). Insulin, glucose, fructosamines concentrations and body weight were monitored during four sampling periods (S0-S3), while pasture variables were analyzed during three periods (S1-S3). The concentration of water-soluble carbohydrates was highest in May (126.8 g/kg DM) and measured lower in October (57.9 g/kg DM), while s...
Histomorphometric Analysis of the Endometrium of Jennies (Equus asinus) and Mares (Equus caballus) in Estrus: Anatomical Differences and Possible Reproductive Implications. Assisted reproductive techniques are often extrapolated from horses to donkeys, despite poorer fertility outcomes in jennies. This issue has been attributed to unknown uterine species-specific differences. This study compared, through histomorphometry, the endometrium of jennies and mares. Endometrial biopsies (N = 12) were taken from reproductively sound jennies (n = 6) and mares (n = 6) in estrus. Histomorphometric analysis evaluated luminal (LE, µm) and glandular epithelium height (GE, µm), glandular lumen diameter (LD, µm), glandular area (GA, µm), the number of glands (#G), and glandu...
Molecular prevalence of equine alphaherpesvirus-1 shedding in healthy broodmares in Ontario. Equine herpesvirus-1 (EHV-1) is ubiquitous in the horse population, but prevalence estimates have ranged from 3 to 88% depending on the population and method of sampling. No prevalence studies have been carried out in Ontario, Canada. The objective of this study was to measure the prevalence of EHV-1 shedding in healthy broodmares in Ontario. A total of 381 mares from 42 farms in Ontario were sampled, including pregnant and barren broodmares. Samples were collected from the nose, vagina, and blood of each mare up to 6 times from December 2016 through October 2017 using a cross-sectional study ...
Evaluation of a modified one-stage technique for repair of third-degree perineal laceration and rectovestibular fistula with rectal pull-back technique in 12 mares: a retrospective case series. This study was carried out to evaluate a rectal pull-back one-stage technique, which is a modification of the one-stage Goetz technique, for treating third-degree perineal laceration or rectovestibular fistula. Methods: This study was performed on 12 mares, ten of whom suffered from third-grade perineal laceration, and two suffered from rectovestibular fistula and were included in this study. After incision of the vestibular shelf horizontally, the dissected rectal flap was pulled caudally and sutured to the anal sphincter during its reconstruction at the final stage. While the vestibular shel...
Vaccination against Hendra virus of previously unvaccinated mares and their foals demonstrates the effectiveness of the current prime and boost vaccination schedule for foals. Hendra virus (HeV) is a high consequence pathogen that causes severe respiratory and/or neurological disease in both horses and humans with high mortality. The equine vaccine, Equivac® HeV, is a recombinant soluble version of the G glycoprotein of HeV (HeV-sG) that elicits a potent HeV-neutralising antibody response in adult horses and also provides indirect protection for humans. Maternally derived HeV-G specific antibodies could interfere with subsequent foal vaccination, although other factors such as foal age and the suitability of vaccination protocols that have been optimised for adult ...
Reference Values and Association of Body Weight, Age, and Sex With Echocardiographic Measurements in Non-Athletic Quarter Horses. Echocardiographic reference intervals for Quarter Horses are infrequently reported. Objective: To provide standard echocardiographic measurements for sedentary Quarter Horses and evaluate the relationship between physical characteristics (body weight, age, sex) and echocardiographic measurements. Methods: Forty-one sedentary Quarter Horses, free of cardiac disease, from a university research herd. Methods: A cross-sectional study evaluating standardized echocardiograms performed on sedentary Quarter Horses (41) between 2020 and 2022. Reference intervals were calculated for raw and weight-corre...
Lipopolysaccharide reduces progesterone and cytokines in equine follicular fluid without affecting oocyte development in vitro. Lipopolysaccharide (LPS) in follicular fluid impairs steroid production and oocyte developmental competence in cows and mice. This study assessed LPS concentrations in equine follicular fluid and their association with steroid and some cytokine levels. Additionally, we evaluated whether LPS exposure during in vitro maturation (IVM) affects equine oocyte developmental competence. In experiment 1, follicular fluid from large follicles (>30 mm in diameter) was collected from 16 slaughterhouse mares, and concentrations of LPS, estradiol, progesterone, TNF-α, and IL-6 were measured. In experiment...
Cortisol and heart rate response of mares during the in-hand breeding procedure with and without restraint. In-hand breeding involving restraint methods is likely the most common practice in the horse breeding industry worldwide. However, welfare issues that arise from such management have not been investigated in detail. Objective: (1) To investigate whether the mares show increased stress responses during in-hand breeding using (a) a lip twitch and (b) hobbles. (2) To evaluate if the use of restraint methods influences the mare's expression of oestrous behaviour. Methods: Intra-individual cross-over design. Methods: Six Franches-Montagnes stallions and 10 warmblood mares were used in these experim...
Associations between endometrial swab bacteriology and cytology findings and live foal rates in Thoroughbred broodmares in the United Kingdom. To date, relationships between pre-covering endometrial swab cytology and bacteriology and fertility outcomes in Thoroughbred broodmares in the United Kingdom are unknown and could aid clinical decision making. Objective: To investigate associations between cytology and bacteriology findings from the last endometrial swab taken in the breeding season (15 February to 15 July) and live-foal rates (predicted mean probability of producing a live foal) in UK Thoroughbred broodmares. Methods: Retrospective cohort study. Methods: Endometrial cytology and bacteriology findings were extracted from labo...
Born to run? Associations between gestational and early-life exposures and later-life performance outcomes in Thoroughbreds. Gestational and early-life exposures may modulate development during growth and influence future athletic performance. Objective: To investigate associations between gestational and early-life exposures in Thoroughbreds and (i) likelihood of racing, (ii) total number of runs and (iii) total prizemoney by the end of the 3-year-old year. Methods: Prospective cohort. Methods: Daily records were kept on the location and duration of turnout, management and veterinary-attended episodes of disease or injury from birth until leaving the farm or study exit for 129 Thoroughbred foals on six stud farms. ...
Retrospective Evaluation of Dystocia in Miniature Equids: 78 Cases (2002-2023). To describe patient characteristics, laboratory data, fetal orientation, methods of correction, survival, and treatment in miniature equids with dystocia. Methods: Retrospective study conducted from January 2002 to June 2023. Methods: Equine referral hospital and field service. Methods: Seventy animals with a total of 78 instances of dystocia. Methods: None. Results: Recorded variables included signalment, clinicopathologic data, fetal presentation, correction method, survival to discharge, and complications. The survival of miniature equid mares was 94% (73/78), while survival of foals was 17...
Investigations on metabolic diseases of horses in Egypt. Obesity is a significant risk factor that predisposes horses to laminitis, equine metabolic syndrome, arthritis, heart disease, and respiratory issues. Unassigned: Mares showing overweight or laminitis ( = 30), different BCS ( = 90) weighing 350-550 Kg were subjected to clinical and rump fat assessments. Blood samples were collected to measure circulating estradiol, progesterone, cortisol, insulin, insulin-like growth factor-1 (IGF-1), and leptin. Additionally, glucose, cholesterol, triglycerides, total proteins, albumin, nitric oxide (NO), lactate dehydrogenase (LDH), glutathione redu...
Melatonin receptors and thyroid stimulating hormone in the equine pars tuberalis: Potential modulators of seasonal reproduction in the mare. The mechanism by which photoperiod influences the hypothalamic-pituitary-gonadal (HPG) axis and regulates seasonal reproduction in horses has yet to be fully elucidated. The hypophyseal pars tuberalis (PT) has been indicated as a critical site for the transduction of melatonin signals through melatonin-responsive, PT-specific cells that produce thyroid-stimulating hormone (TSH) in many mammalian species. However, this has yet to be investigated in horses. The objective of this study was to explore the interaction of melatonin and thyroid-stimulating hormone in the equine HPG axis. Pituitaries ...
Evaluation of age effect on circulating catecholamines’ network in pregnant mares. Catecholamines (CATs) are essential neuroendocrine regulators with plasma concentrations that naturally fluctuate during pregnancy. Age-related changes in CATs, observed in humans and animals, suggest that gestation and aging together influence catecholaminergic activity. Blood samples were collected from Spanish Purebred mares categorized into three age cohorts (4-7 years, n = 18; 8-10 years, n = 18; 11-15 years, n = 18) across four defined gestational stages: first trimester (T1), second trimester (T2), third trimester (T3), and the final bimester (B4). Plasma concentrations of a...
Management of retained fetal membranes by umbilical vessel infusion in mares submitted to elective C-section. The cesarian section (C-section) is a potential risk factor for retained fetal membranes (RFM) in mares, requiring prompt diagnosis and treatment to enhance outcomes. This study aimed to evaluate the use of umbilical vessel infusion for the treatment of RFM after elective C-section in mares. Ten pregnant criollo type-mares at 315 days of gestation were monitored daily and underwent elective C-section upon readiness for birth. All mares exhibited RFM, with placentas retained beyond three hours careful extraction of the foal by C-section. Those were randomly assigned into two groups: Umbilical v...