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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.
Evaluation of the ocular surface mycobiota in clinically normal horses. The eye is host to myriad bacterial, fungal, and viral organisms that likely influence ocular surface physiology in normal and diseased states. The ocular surface mycobiota of horses has not yet been described using NGS techniques. This study aimed to characterize the ocular surface fungal microbiota (mycobiota) in healthy horses in 2 environmental conditions (stalled versus pasture). Conjunctival swabs of both eyes were obtained from 7 adult stallions stabled in an open-air pavilion and 5 adult mares living on pasture. Genomic DNA was extracted from ocular surface swabs and sequenced using pr...
Impaired Reproductive Function in Equines: From Genetics to Genomics. Fertility is one of the key factors in the economic and productive success of the equine industry. Despite this, studies on the genetic causes affecting reproductive performance are scarce, especially in mares, where the genetic architecture of the reproductive traits is extremely complex. Today, with the increasing availability of new genomic methodologies for this species, we are presented with an interesting opportunity to understand the genetic basis of equine reproductive disorders. These include, among others, novel techniques for detecting chromosomal abnormalities, whose association wi...
Overfeeding Extends the Period of Annual Cyclicity but Increases the Risk of Early Embryonic Death in Shetland Pony Mares. Obesity has been associated with altered reproductive activity in mares, and may negatively affect fertility. To examine the influence of long-term high-energy (HE) feeding on fertility, Shetland pony mares were fed a diet containing 200% of net energy (NE) requirements during a three-year study. The incidence of hemorrhagic anovulatory follicles (HAF) and annual duration of cyclicity were compared to those in control mares receiving a maintenance diet. Day-7 embryos were flushed and transferred between donor and recipient mares from both groups; the resulting conceptuses were collected 21 day...
Detection and longitudinal distribution of GW1516 and its metabolites in equine hair for doping control using liquid chromatography/high-resolution mass spectrometry. GW1516 is a peroxisome proliferator-activated receptor-δ (PPAR-δ) agonist that is banned in horseracing and equestrian sports. Long-term detection and longitudinal distribution of GW1516 in the mane of a horse are reported for the first time and this hair analysis could prolong the detection window of GW1516 for doping control. Methods: Mane hairs were divided into three segments (0-7, 7-15, and >15 cm from the cut end) and completely pulverized and homogenized for analysis. The pulverized hair samples were extracted with methanol followed by further purification and the extracts were a...
Isolation and Characterization of Equine Uterine Extracellular Vesicles: A Comparative Methodological Study. Extracellular vesicles (EVs) have been identified in the uterine fluid in different species and have been pointed as key players in the embryo-maternal dialogue, maternal recognition of pregnancy and establishment of pregnancy. However, little is known about the uterine EVs in the mare. Therefore, the present study aimed at characterizing EVs from uterine lavage of cyclic mares by comparing five EVs isolation methods and the combination of them: (1) ultracentrifugation (UC); (2) concentration of lavage volume by Centricon ultrafiltration (CE); (3) the use of CE with different washing steps (ph...
The contraceptive efficacy of a self-assembling intra-uterine device in domestic mares. The primary aim of this study was to investigate the contraceptive efficacy of a self-assembling uterine device (iUPOD™) in the mare. In addition, the effects of iUPODs on oestrous cyclicity, uterine health and circulating concentrations of cortisol were evaluated. Methods: Domestic mares underwent oestrous monitoring and artificial insemination. After subsequent ovulation, mares underwent either placement (n = 7) or sham placement (n = 7; controls) of an iUPOD device. Devices were left in place for at least 3 months. Pregnancy diagnoses were carried out 14 days post-ovulation, with any pr...
Effects of Leaving Amputated Ovaries Intra-Abdominally during Elective Bilateral Standing Laparoscopic Ovariectomy in Equids. There is risk of dropping an amputated ovary within the abdomen during standing laparoscopic ovariectomies in mares. If the ovary can no longer be directly visualized with the laparoscope, the procedure is then converted to a flank laparotomy for manual retrieval of the ovary which negates the minimally invasive nature of the laparoscopic procedure. The objective was to identify if ovaries left in the abdomen after amputation would atrophy or if they re-vascularize. Standing bilateral ovariectomies were performed in mature mares, but after transection of the ovarian pedicle, the ovaries were i...
Clinical Observations After Prebreeding Intrauterine Plasma Infusion in 18 Mares Inseminated With Thawed Frozen Semen. The use of autologous blood processing tools including platelet-rich plasma (PRP) devices is increasingly widespread in veterinary medicine. In equine reproduction, a number of studies have explored the effects of intrauterine infusion of PRP on persistent mating-induced endometritis. Artificial insemination with thawed frozen semen incites an intrauterine inflammatory response and we sought to extend the applications of intrauterine PRP to normal mares being inseminated with frozen semen. We investigated a subset of our normal breeding population to observe the clinical effects of prebreeding...
Myeloperoxidase Inhibition Decreases the Expression of Collagen and Metallopeptidase in Mare Endometria under In Vitro Conditions. Neutrophils can originate neutrophil extracellular traps (NETs). Myeloperoxidase (MPO) is a peroxidase found in NETs associated to equine endometrosis and can be inhibited by 4-aminobenzoic acid hydrazide (ABAH). Metallopeptidases (MMPs) participate in extracellular matrix stability and fibrosis development. The objectives of this in vitro work were to investigate, in explants of mare's endometrium, (i) the ABAH capacity to inhibit MPO-induced collagen type I (COL1) expression; and (ii) the action of MPO and ABAH on the expression and gelatinolytic activity of MMP-2/-9. Explants retrieved from...
Importance of broth-enrichment culture in equine endometritis diagnosis. The objective of this study was to investigate the diagnostic accuracy of the standard microbiological protocol to assure the evaluation of bacterial endometritis in the equine clinical practice. Four hundred fifty-two equine uterine swabs were seeded on different types of agar plates and then in a broth-enrichment (Brain Heart Infusion Broth) before plating by using the same media the day after. The prevalence of positivity was 33.7% following direct plating and 66.3% following use of added enrichment-broth phase before seeding on solid media. Furthermore, the prevalence of isolated bacteria ...
Intrauterine infusion of killed semen adversely affects uterine blood flow and endometrial gene expression of inflammatory cytokines in mares susceptible to persistent breeding-induced endometritis. Persistent breeding-induced endometritis (PBIE) is a leading cause of infertility in mares. The objective of the study was to assess genital perfusion and endometrial gene expression of inflammatory cytokines in mares classified as susceptible (n = 5) or resistant (n = 5) to PBIE. Ten mares were examined daily during estrus until 6 d after hCG-induced ovulation for two estrous cycles. Twenty-four hours after application of 1500 IU hCG, 4 mL of killed (by repeated freezing in liquid nitrogen and thawing at 50 °C) deep-frozen semen or sterile saline was instilled into the uterine body an...
The imbalance of the Th17/Treg axis following equine ascending placental infection. Ascending placentitis is a leading cause of abortion in the horse, but adaptive immune response to this disease is unknown. To evaluate this, sub-acute placentitis was experimentally-induced via trans-cervical inoculation of S. zooepidemicus, and endometrium and chorioallantois was collected 8 days later (n = 6 inoculated/n = 6 control). The expression of transcripts relating to Th1, Th2, Th17, and Treg maturation was assessed via RNASeq. IHC of transcription factors relating to each subtype in the same tissues (Th1: TBX21, Th2: GATA3, Th17: IRF4, Treg: FOXp3). An immunoassay was utili...
Grazing Mares on Pasture with Sycamore Maples: A Potential Threat to Suckling Foals and Food Safety through Milk Contamination. Equine atypical myopathy (AM) is seasonal intoxication resulting from the ingestion of seeds and seedlings of the sycamore maple (Acer pseudoplatanus) that contain toxins, among them, hypoglycin A (HGA). Literature mentions several cases of AM among gravid mares and in unweaned foals. The objective of this study was to determine whether HGA and/or its metabolite are present in milk from grazing mares exposed to sycamore maple trees as confirmed by detection of HGA and its metabolite in their blood. Four mare/foal couples were included in the study. Both HGA and its metabolite were detectable i...
Timed artificial insemination in crossbred mares: Reproductive efficiency and costs. Timed artificial insemination (TAI) has boosted the use of conventional artificial insemination (CAI) by employing hormonal protocols to synchronize oestrus and ovulation. This study aimed to evaluate the efficiency of a hormonal protocol for TAI in mares, based on a combination of progesterone releasing intravaginal device (PRID), prostaglandin (PGF2α ) and human chorionic gonadotropin (hCG); and compare financial costs between CAI and TAI. Twenty-one mares were divided into two groups: CAI group (CAIG; n = 6 mares; 17 oestrous cycles) and TAI group (TAIG; n = 15 mares; 15 oestrous cycle...
The Effect of Uterine Lavage on Soluble CD14, Chemokine Ligand 2, and Interleukin 10 Levels in Mares With Postpartum Metritis. Postpartum metritis in mares is a life-threatening condition associated with severe clinical signs due to endotoxemia, and it is often followed by complications such as laminitis. Repeated large-volume uterine lavages are commonly recommended as a part of the treatment protocol to remove endotoxin-laden contents from the uterus. It has, however, also been suggested that lavages may increase the uptake of endotoxin into the circulation, leading to a deterioration of clinical signs. Endotoxemia is associated with the release of a multitude of inflammatory mediators regulating the immune response...
Addition of caffeine to equine thawed sperm increases motility and decreases nitrite concentration. The aim of this study was to improve the quality of frozen-thawed equine sperm by the addition of caffeine to it. Semen from nine stallions was frozen and different concentrations of caffeine (3, 5 and 7.5 mM) were added to frozen-thawed semen. The sperm kinetic parameters, membrane functionality and integrity, and acrosome integrity and spontaneous acrosome reacted sperm were evaluated with a computer-assisted sperm analysis, a hypoosmotic swelling test and epifluorescent microscopy, respectively. Nitrite and hydroperoxide concentrations of frozen-thawed semen were measured using spectrophot...
Bacterial dispersal and drift drive microbiome diversity patterns within a population of feral hindgut fermenters. Studies of microbiome variation in wildlife often emphasize host physiology and diet as proximate selective pressures acting on host-associated microbiota. In contrast, microbial dispersal and ecological drift are more rarely considered. Using amplicon sequencing, we characterized the bacterial microbiome of adult female (n = 86) Sable Island horses (Nova Scotia, Canada) as part of a detailed individual-based study of this feral population. Using data on sampling date, horse location, age, parental status, and local habitat variables, we contrasted the ability of spatiotemporal, life history...
Abortion and uterine prolapse in a Thoroughbred mare with twin pregnancy: Clinical and laboratory findings and treatment approach. This report presents a case of uterine prolapse in a Thoroughbred mare. The uterine prolapse occurred after abortion of twins in the eighth month of gestation. The prolapsed uterus was bleeding and congested but not damaged. The placenta was still attached to the endometrium. Blood samples were collected for hematology and for estimation of calcium, progesterone and estrogen. The cervix and clitoris were swabbed for bacteriology. The mare showed a decrease in the number of lymphocytes. The concentrations of estrogen and progesterone seemed normal compared with mares that foaled. Pseudomonas ae...
Case Report of a Mare Diagnosed with a Metastatic Mammary Carcinoma after the Excision of a Recurrent Intraocular Neuroepithelial Tumor. A 24-year-old Irish Cob mare was presented with a peripheral iris mass, which was surgically resected and diagnosed as an undifferentiated neuroepithelial tumor. A few months later, a relapse occurred with histological features characterized by a more solid appearance and squamous differentiation. Subsequently, the mare was presented with rapidly spreading multiple subcutaneous masses and, at the onset of neurological signs, was humanely euthanized and subjected to a complete post mortem examination. The necropsy confirmed the presence of numerous widespread masses in the subcutaneous tissue, ...
Two Novel Cases of Autosomal Translocations in the Horse: Warmblood Family Segregating t(4;30) and a Cloned Arabian with a de novo t(12;25). We report 2 novel autosomal translocations in the horse. In Case 1, a breeding stallion with a balanced t(4p;30) had produced normal foals and those with congenital abnormalities. Of his 9 phenotypically normal offspring, 4 had normal karyotypes, 4 had balanced t(4p;30), and 1 carried an unbalanced translocation with tertiary trisomy of 4p. We argue that unbalanced forms of t(4p;30) are more tolerated and result in viable congenital abnormalities, without causing embryonic death like all other known equine autosomal translocations. In Case 2, two stallions produced by somatic cell nuclear tran...
Incidence and causes of pregnancy loss after Day 70 of gestation in Thoroughbreds. Pregnancy loss after Day 70 of gestation manifests as abortion, stillbirth or perinatal death. While previous studies have reported the diagnoses of laboratory submissions, none have quantified the incidence and causes of abortions, stillbirths and perinatal mortality at a population level. Objective: To report the incidence and causes of pregnancy loss after Day 70 of gestation in a cohort of Thoroughbreds. Methods: Retrospective cohort study. Methods: Outcomes of Day 70 pregnancies were collected from eight Thoroughbred farms over the 2013-2017 breeding seasons. Stud, veterinary and laborato...
Evaluation of the efficiency of TaqMan duplex real-time PCR assay for non-invasive pre-natal assessment of foetal sex in equine. Accurate diagnosis of foetal sex in pregnant mare is helpful for many breeders, both for private or commercial purposes. In this study, in order to pre-natal foetal sexing in equine, we used TaqMan duplex real-time PCR to detect the specific regions of SRY and TSPY genes on extracted cell-free foetal DNA from maternal blood. Peripheral blood samples from 50 pregnant Arabian mares with singleton foetuses were collected. Cell-free foetal DNA was extracted from maternal plasma, and duplex real-time PCR assays were performed with TaqMan probes and primers. Amplification of glyceraldehyde-3-phospha...
A deterministic simulation model for the evaluation of reproductive performance in Thoroughbred mares. The objective of the present study was to develop a deterministic simulation model for evaluating the reproductive performance of Thoroughbred mares. As an application, the model was used to estimate the herd level asymptotic foaling percentage (AFP) for evaluating the performance of mares in stabilized mare herds using the convergent method for estimating a steady-state distribution of mares. In this model, it was assumed that the mares were mated only during the breeding season. The effects of early pregnancy loss and fetal loss on reproductive performance were investigated. The sensitivitie...
A new strain of Taylorella asinigenitalis shows differing pathogenicity in mares and Jenny donkeys. Three horse mares inadvertently inseminated with semen from a Tayorella asinigenitalis-positive Jack donkey developed severe, purulent endometritis whereas two Jenny donkeys mated naturally to the same Jack donkey did not develop clinical signs of infection. Objective: To isolate and identify the causative agent. Methods: Case report. Methods: Endometrial swabs from the infected mares were cultured on selective and non-selective media under aerobic and microaerophilic conditions. Isolates were subjected to Gram staining, oxidase and catalase tests, the Monotayl Latex Agglutination test and PCR...
A 25-year retrospective study of Chlamydia psittaci in association with equine reproductive loss in Australia. is primarily a pathogen of birds but can also cause disease in other species. Equine reproductive loss caused by has recently been identified in Australia where cases of human disease were also reported in individuals exposed to foetal membranes from an ill neonatal foal in New South Wales. The prevalence of in association with equine reproductive over time and in different regions of Australia is not known. This study was conducted to detect in equine abortion cases in Australia using archived samples spanning 25 years. We tested for in 600 equine abortion cases reported in Australia ...
Two different clinical forms of squamous cell carcinoma (SCC) in the perineum and vulva of two mares. Genital malignant neoplasms in mares are relatively rare. The treatment involve surgical removal of the tumour masses, chemotherapy or both. Methods: Two elderly warmblood mares, aged 16 and 20 were presented in University Clinic with the lumpy lesions at the region of perineum and left labia. Surgical removals of tumour masses were performed on standing animals. Removed tissues were subjected to histopathological examination which confirmed SCC. Conclusions: Clinical and ultrasound examination of reproductive organs in both mares showed no inflammatory or neoplastic changes. Both mares healed...
Diestrous Ovulations in Pregnant Mares as a Response to Low Early Postovulatory Progestogen Concentration. Spontaneous prolongation of the luteal phase has been described in horses, but the underlying causes are still unclear. The present study investigated details of gonadotrophin and progestogen secretion in pregnant mares (n = 11) with or without experimentally reduced early postovulatory luteal function. From days 0 to 3 after ovulation, they were treated with the prostaglandin F (PGF) analogue cloprostenol or left untreated. After conceptus collection on day 34, they were assigned to the opposite treatment. Mares were affiliated to the group primary corpus luteum (n = 6) or diestrous corpus lu...
Recovery of Equine Oocytes in Ambulatory Practice and Potential Complications. Field collection of oocytes in mares using transvaginal follicular aspiration (TVA) for embryo production has the potential to revolutionate the equine industry. Protocols for TVA in specialized laboratory settings have been described in the scientific literature since the early 1980s. The objective of this study was to determine the success rate of TVA oocytes recovery under ambulatory conditions. A secondary goal of this study was to determine if TVA is associated with any health complications when performed by recently trained practitioners in the field. Follicles (n = 296) from 66 adult c...
Evaluation of Colostral Immunity Against Equine Herpesvirus Type 1 (EHV-1) in Martina Franca’s Foals. Eight Martina Franca pregnant jennies were selected in order to evaluate the transfer of colostral antibodies against equine herpesvirus type 1 in their relative foals after immunization with a commercial inactivated vaccine, compared with an unvaccinated group. Samples of serum and colostrums/milk were collected from jennies and foals under study starting from 10 min before and up to 21 days after the foaling. Specific anti-EHV-1 antibody titers were evaluated by means of a serum neutralization test, and the results obtained from both groups were analyzed. The serological titers in the vaccin...
Monitoring equine ascarid and cyathostomin parasites: Evaluating health parameters under different treatment regimens. Strongylid and ascarid parasites are omnipresent in equine stud farms, and ever-increasing levels of anthelmintic resistance are challenging the industry with finding more sustainable and yet effective parasite control programs. Objective: To evaluate egg count levels, bodyweight and equine health under defined parasite control protocols in foals and mares at two Standardbred and two Thoroughbred stud farms. Methods: Longitudinal randomised field trial. Methods: A total of 93 foals were enrolled and split into two treatment groups, and 99 mares were enrolled and assigned to three treatment gro...
