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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.
Fungal endometritis in broodmares: clinical presentation, prevalence in Ireland and diagnostic performance of cytology. Fungal endometritis is an uncommon uterine condition associated with poor fertility. Objective: This study aimed to 1) provide a descriptive summary of 11 cases of fungal endometritis, 2) assess prevalence trends of fungal endometritis over time, 3) assess fungal species distribution in diagnostic samples, and 4) evaluate the diagnostic accuracy of cytology. Methods: Study 1 reviewed records of 11 mares diagnosed with fungal endometritis for history, presentation, treatment, and outcome. Study 2 analysed 6,727 uterine samples (swabs and lavages; 2019-2024) for factors influencing fungal cultur...
Periovulatory administration of therapeutic and supratherapeutic doses of firocoxib does not impair induced ovulation or follicular dynamics in mares treated with a GnRH analogue. To evaluate the effects of therapeutic and supratherapeutic periovulatory doses of firocoxib on ovulation and follicular dynamics in mares. Methods: Seventy cycling mares were randomly assigned to receive firocoxib at 0.1 mg/kg (n = 27), firocoxib at 0.3 mg/kg (n = 22), or no treatment (control; n = 21). Treatments were initiated on Day 0, defined as the day of ovulation induction with a GnRH analogue administered intramuscularly, with firocoxib administered intravenously on Day 0 and Day 1 (24 h apart). Follicular diameter and ovulation timing were assessed by transrectal ultrasonography. Res...
Saliva and plasma metabolome analysis during the five days before foaling in the mare. Saliva is a relevant biofluid for real-time welfare-friendly monitoring of systemic events in animals, because some bioanalytes have a systemic origin and its collection is painless, stress-free and non-invasive. Our aim was to analyze the metabolome of equine saliva during the five days before foaling, with a focus on identifying metabolites whose level significantly changed before parturition, that could be potential salivary biomarkers of the onset of parturition. We compared the saliva and plasma metabolomes to investigate their relationship. Saliva and blood samples were collected from tw...
Population Structure and Genetic Diversity Among Lipizzan Mare Families in Hungary Based on Microsatellite Genotyping. The conservation of genetic diversity in historically structured horse breeds requires fi-ne-scale population genetic evaluation beyond conventional pedigree-based approaches. The present study assessed genetic diversity, population structure, and mare family differentiation in a Lipizzan horse population using 16 ISAG/FAO-recommended microsatellite markers. A total of 172 mares representing 29 mare families were genotyped. All loci were polymorphic, with a mean number of alleles per locus of 6.69 and a mean effective number of alleles of 3.56. The average polymorphism information content (PIC...
Endometrial Evaluation Using Video-Assisted Hysteroscopy After Uterine Prolapse Management in a Mare. This case report describes the successful application of video-assisted hysteroscopy to evaluate endometrial recovery in a 6-year-old mare following treatment for complete uterine prolapse secondary to dystocia. Upon presentation, the uterus was manually reduced and supported with a Buhner's suture. A multimodal medical protocol, including broad-spectrum antibiotics, anti-inflammatory drugs and uterine lavage, was initiated. Five days after reduction, an endoscopic evaluation was performed using a dedicated videovaginoscope without uterine insufflation. The procedure provided high-resolution i...
Comparative analysis of uterine inflammation in jennies and mares after insemination with cryopreserved donkey semen. The limited fertility of jennies inseminated with frozen donkey semen remains a major challenge for donkey reproduction and conservation, contrasting with the more favorable outcomes observed in mares. Species-specific differences in post-breeding uterine inflammation have been proposed as a key factor underlying this disparity. This study compared the uterine inflammatory response and pregnancy outcomes of jennies and mares inseminated with frozen donkey semen. Twelve jennies and eleven mares were monitored over 48 and 44 estrous cycles, respectively. Artificial insemination (AI) was performe...
Impact of donor mare and stallion identity on the likelihood of pregnancy after transfer of in vitro produced embryos. The success of in vitro embryo production (IVEP) is influenced by donor mare and stallion. Objective: To determine whether donor mare and stallion influence the pregnancy rate after transfer of in vitro produced (IVP) blastocysts and to identify factors influencing the likelihood of obtaining one or more pregnancies from a single IVEP session. Methods: Retrospective clinical study. Methods: The influence of the following variables on pregnancy outcome was assessed in 2292 transfers of IVP blastocysts: speed of in vitro embryo development, embryo grade after thawing, age of the donor mare, blas...
Synthetic progestin treatment alters cytokine expression and impairs vaccine response in horses. Altrenogest is commonly used in equine veterinary medicine for the control of estrus, behavioral modifications, and maintenance of pregnancy. Recent studies have found that altrenogest may impact aspects of the immune system, including altering cytokine production in circulation and within the reproductive tract. Therefore, we hypothesize that this alteration may lead to a deviated immune response to vaccination. Sixteen mares were divided into two groups, with ten mares (n = 10) receiving long-acting injectable altrenogest (100 mg/mL; IM) administered every 10 days, and six mares (n =...
Generation of equine-specific local antibiograms: reproductive tract of mares and fillies in Western Australia. Antimicrobial resistance (AMR) may lead to increasing inefficacy and treatment failure of bacterial infections in the future. Antimicrobial stewardship (AMS) programmes are critical to ensuring the continued efficacy of available antimicrobials. There is a lack of published evidence-based data on the susceptibility of isolates from common reproductive infections encountered in mares. This study aims to provide equine veterinarians in Western Australia (WA) with the most appropriate first-line empirical antimicrobials for infections of the mare reproductive tract. Methods: A retrospective study...
Impacts of flavor and aromatic palatants on consumption behavior in nursing foals. Palatability research in horses has primarily been conducted in mature, non-lactating horses and has typically investigated gustatory rather than aromatic preference. Objective: The objective of this study was to investigate the gustatory and aromatic preferences of nursing foals. Methods: Stock-type mare (13.25 ± 4.40 years) and foal (6 ± 3 weeks) pairings (n = 4) were utilized in multi-preference testing for treatments including apple, anise, peppermint and control (no palatant). Mares and foals were placed in assigned split stalls for 1800 seconds and provided unrestricted access to a...
Clinical pregnancy outcomes after transfer of fresh and vitrified-warmed conventional IVF equine embryos. In vitro fertilization (IVF) in horses has emerged as a valuable assisted reproductive technology, yet the impact of embryo cryopreservation on pregnancy outcomes when utilizing this technique remains unclear. This study reports pregnancy outcomes following transfer of conventional equine IVF embryos, with both fresh and vitrified-warmed embryos. Conventional IVF (cIVF) was used to produce 40 embryos, which were transferred to recipient mares, pregnancy diagnosis was performed at 6 days post-transfer followed by embryonic heartbeat detection between day 25 and 30 of gestation. Observed pregnan...
Embryonic vesicle diameter at first pregnancy diagnosis in in vivo- and in vitro-derived pregnancies and its relationship with pregnancy loss in the mare. This retrospective study compared the relationship between embryonic vesicle diameter at first pregnancy diagnosis and early embryonic loss (EEL) across three pregnancy types: artificially inseminated broodmares (AI; n = 263), recipients carrying in vivo-derived flushed embryos (IVD-F; n = 312), and recipients carrying in vitro-produced embryos by intracytoplasmic sperm injection (IVP-ICSI; n = 161). Vesicle diameter was recorded at Day 12 post-ovulation in AI, Day 4 post-embryo transfer (ET) for IVD-F, and Day 7 post-ET for IVP-ICSI pregnancies. Mean (±SD) vesicle diameters and E...
Multicentric Malignant Melanoma in a Grey Mare: A Case Report. Grey coat color in horses, resulting from a 4.6 kb copy number variation (CNV) within the syntaxin 17 (STX17) gene (Grey locus), is linked to progressive hair depigmentation and a markedly increased risk of melanoma, likely to its function as a melanocyte-specific enhancer. Objective: This report details the clinical, pathological, and genomic findings of a 26-year-old flea-bitten grey mare with multiple melanocytic tumors, progressive dyspnea, and congestive heart failure. Due to the poor prognosis the horse was euthanized and submitted for necropsy to the Long Island University - Lewyt Colle...
Novel application of a PMSG assay for measurement of circulating LH levels in horses. Luteinizing hormone (LH) plays a pivotal role in equine reproductive physiology, yet its measurement has traditionally relied on radioimmunoassays (RIA), which present safety, accessibility, and regulatory challenges. This study evaluates the use of a commercially available pregnant mare serum gonadotropin (PMSG) enzyme-linked immunosorbent assay (ELISA) as an alternative for quantifying circulating LH in horses. Given the 100% peptide identity between equine LH and PMSG, we hypothesized that the PMSG ELISA would detect LH with high specificity and sensitivity. Blood samples from healthy, cycl...
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...
Decoding moody mare syndrome: Retrospective study and tiered diagnostic framework. Behavioral issues, such as persistent or strong estrus, non-specific pain, and performance challenges in mares are frequently attributed to the estrous cycle. Objective: The objectives of this study were to analyze retrospective data on mares presented for estrus-related behavioral complaints, and to propose a structured diagnostic framework for categorizing cases during work-up at different levels of care. Methods: A retrospective study was conducted using patient records of a total of 14993 mares. Results: In this data set, behavioral problems, pain, or poor performance were not repeatably v...
Functional Characterization of Long Non-Coding RNAs Associated with Reproductive Fitness in Pura Raza Española Mares. Long non-coding RNAs (lncRNAs) are transcripts constituted of more than 200 nucleotides that have been associated with the regulation of different biological processes by modulating the expression of key genes. In horses, evidence suggests that lncRNAs play a role in female reproductive fitness, yet their functional implications remain poorly characterized. The objective of this study was to investigate potential DNA:RNA triplex interactions between the promoter regions of fertility-related genes and lncRNAs transcribed from non-coding loci located within ±50 kb of these genes. By doing so, w...
Long-term micronutrient and amino acid supplementation increases embryo recovery per flush and ovarian responsiveness in donor mares. Background: Nutritional strategies may modulate ovarian function and embryo recovery in donor mares, but field evidence for long-term multinutrient supplementation remains limited.Aims/objectivesTo determine whether long-term micronutrient and amino acid supplementation increases embryo recovery per flush and ovarian responsiveness in donor mares.Methods: A total of 115 uterine flushes were performed under a crossover design across two consecutive breeding seasons in 12 multiparous, non-lactating crossbred donor mares (4-12 years). Mares received a basal diet or the same diet plus 40 g/day of ...
Relationship between the duration of endometrial edema and reproductive parameters of estrus, diestrus, and fertility in mares: a field study. The duration of endometrial edema has been positively correlated with uterine receptivity and likelihood of pregnancy. Therefore, this study aimed to evaluate whether there is a relationship between the duration of endometrial edema (DEdema) and other key parameters of the estrous cycle: maximum edema (MEdema), largest follicle diameter (LPF), corpus luteum and uterine tone on day 5 post ovulation (CLD5 and TD5), progesterone concentration (P4) and fertility. A total of 88 cycles from 36 mares were evaluated and divided into Short Estrus (SE), Long Estrus (LE), Inseminated (AI) and Non-insemin...
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...
Confocal laser endomicroscopy: exploring endometrial image quality in relation to the oestrous cycle of mares. Assessment of the endometrium is an essential component of a breeding soundness examination in mares. The current reference standard for evaluating equine endometrial health is histopathological assessment of an endometrial biopsy, however, inconsistencies may arise when a single blinded biopsy is used. Confocal laser endomicroscopy (CLE) is non-invasive and enables real-time in-vivo imaging of the endometrium across multiple locations within the uterine lumen. An initial study revealed variation in CLE image quality between mares. Objective: This study aimed to compare the quality of endometr...
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...
Effects of L-selenomethionine supplementation on nutrient digestibility and metabolism, antioxidant capacity, hormone levels, and fecal microbiota diversity in pregnant Yili mares during mid- to late gestation. L-selenomethionine (L-SeMet), a highly bioavailable organic form of selenium, plays a critical role in maintaining antioxidant homeostasis, regulating reproductive hormone secretion, and improving intestinal microbial ecology. Previous studies have demonstrated that appropriate supplementation with L-SeMet can significantly enhance the production performance and health status of ruminants. However, the nutritional regulatory mechanisms and physiological effects of L-SeMet in monogastric herbivores, particularly horses during mid- to late gestation, remain inadequately understood. Therefore, th...
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...
