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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.
The roles of the epididymis and prostasomes in the attainment of fertilizing capacity by stallion sperm. The epididymis is a long, tightly coiled tube within the lumen of which sperm matures. Sperm maturation involves morphological and biochemical changes in the sperm plasma membrane in response to epididymal secretions and their various proteins. Some of these proteins become outer membrane components while others become integral membrane proteins; transfer of some proteins to the sperm plasma membrane may be mediated by epididymosomes. Nevertheless, the molecular pathways by which spermatozoa acquire fertilizing capacity during their transit through the epididymis remain ambiguous. In a recent ...
Miniature ponies: 1. Follicular, luteal and endometrial dynamics during the oestrous cycle. Follicular dynamics were studied during 12 interovulatory intervals (IOIs) and 36 preovulatory periods in Miniature mares. The percentage of IOIs with the following follicle events was: ovulatory wave with only one follicle>or=10 mm (55%), diameter deviation similar to previous reports in larger mares (25%) and minor waves emerging before or after the ovulatory wave (55%). Follicle data were compared among Miniature ponies, large ponies and Breton horses (n=12 IOIs per breed). The IOI was longer (P<0.001) in Miniature ponies (23.3+/-0.9 days) and in large ponies (23.9+/-0.5 days) than in...
Melengestrol acetate as a tool for inducing early ovulation in transitional mares. The efficacy of melengestrol acetate (MGA) to shorten the vernal transition of mares by synchronising and accelerating the first ovulation of the year after 60 days of phototherapy was determined by ultrasonographic monitoring. Sixteen mares in late transition were fed two doses of MGA (150 mg/mare/day and 100 mg/mare/day, respectively) for 10 days. A luteolytic dose of prostaglandin was administered to each mare one day after the end of MGA treatment. The presence and duration of oestrus, follicular growth, uterine oedema and presence of ovulation were monitored by ultrasonography and the cer...
Differences in ability of jennies and mares to conceive with cooled and frozen semen containing glycerol or not. A suitable method for the cryopreservation of donkey semen would be very valuable for the ex situ management of genetic diversity in this species. This report uses a variety of observation and trials to evaluate the effect of cryoprotectants in per-cycle pregnancy rates (PC) in equids females (jennies (donkey) and mares (horse)). This was explored by (1) comparing the results of insemination of jennies and mares with cooled or frozen donkey semen, (2) examining the possible toxic effect of the cryoprotectant (CPA) glycerol in these two species and (3) studying alternative solutions. Donkey and...
Passage of postovulatory follicular fluid into the peritoneal cavity and the effect on concentrations of circulating hormones in mares. Reported data were reviewed and reexamined to evaluate the concept that most of the follicular fluid enters the peritoneal cavity at ovulation in mares and transiently alters the circulating concentrations of LH, FSH, estradiol, and inhibin. A transrectal ultrasonographic study supported the hypothesis that the large volume (40-50 ml) of evacuated follicular fluid passes through the infundibular fimbriae into the peritoneal cavity. A spike in circulating inhibin and a decrease in the rate of reduction in circulatory estradiol occurs at ovulation. Simultaneously, a disruption occurs in the incr...
Hormone profiles of mares affected by the mare reproductive loss syndrome. While searching for the cause of the Mare Reproductive Loss syndrome (MRLS), we postulated that 1 of 3 tissues in 40-120 D pregnant mares was the likely primary target of the noxious factor that caused early abortions: The corpora lutea (CL), the endometrium or the fetus and/or its membranes. At this stage of gestation, progesterone (P4) is solely produced by luteal tissue, eCG by endometrial cups in the endometrium and oestrogens by the feto-placental unit. We determined whether concentrations of P4, eCG and/or total conjugated oestrogens (CE) would indicate which tissue was targeted during t...
Morphological features of the placenta at term in the Martina Franca donkey. This study was designed to establish the morphological features of the placenta of the Martina Franca jenny. Ten placentas were harvested at the time of foal delivery and examined both for gross and histological characteristics. The following factors were determined: the total weight and volume of the placenta and its components, the surface area of the allantochorion, umbilical cord length and site of insertion, and the diameter of the umbilical cord vessels and vascular pattern type. The weight of the placenta was similar to previously reported for ponies, and represented 12% of foal birth w...
Effects of exogenous insulin on luteolysis and reproductive cyclicity in the mare. Insulin is a pancreatic hormone that classically regulates carbohydrate and fat metabolism, but also appears to play a role in various reproductive processes. A preliminary study suggested insulin production by day 10 to 18 equine conceptuses. The aim of the present study was to examine the hypothesis that insulin is the conceptus signal responsible for maternal recognition of pregnancy (MRP) in the mare, or otherwise influences reproductive cyclicity during the MRP period. Six Warmblood mares were treated daily during days 7 to 17 after ovulation of two successive oestrous cycles with either ...
Electrolytes changes in mammary secretions before foaling in jennies. No knowledge regarding the peripartum changes in mammary secretions in the jenny are presently available in literature. In the mare, instead, several studies report the role of these changes as indicators of foetal readiness for birth and impending parturition. This experiment was designed to determine calcium, sodium, potassium concentrations, and the value of sodium/potassium ratio in mammary fluids during prepartum in the jenny. Samples were daily collected by hand milking, after mammary gland size increased noticeably, from 17 Martina Franca jennies. Prepartum mammary secretions were analy...
Hemolytic-uremic syndrome in a postpartum mare concurrent with encephalopathy in the neonatal foal. A postpartum mare and foal were presented for evaluation of fever and lethargy in the mare. The mare was diagnosed with endometritis and initially responded well to treatment. On the second day of hospitalization, the mare developed renal insufficiency characterized by oliguria, azotemia, hemolysis, and thrombocytopenia. Concurrently, the foal developed rapidly progressive central nervous system signs culminating in refractory seizures. Both animals failed to respond to treatment and were euthanized. Thrombotic microangiopathy involving glomeruli was evident on microscopic examination of the m...
Management of a gunshot wound in a mare. A 5-year-old, Quarter horse mare was treated for severe cellulitis secondary to a gunshot wound near the right humerus. The bullet was not retrieved due to the risk of damaging the radial nerve or elbow joint. Despite the presence of the bullet, the mare resumed athletic soundness once the infection had resolved. Traitement d’une blessure par balle chez une jument. Une jument Quarter horse âgée de 5 ans a été traitée pour une cellulite sévère à la suite d’une blessure par balle près de l’humérus droit. Le projectile n’a pas été retiré par crainte de léser le nerf radial o...
Equine post-breeding endometritis: A review. The deposition of semen, bacteria and debris in the uterus of the mare after breeding normally induces a self-limiting endometritis. The resultant fluid and inflammatory products are cleared by 48 hours post cover. Mares that are susceptible to persistent post-breeding endometritis (PPBEM) have impaired uterine defence and clearance mechanisms, making them unable to resolve this inflammation within the normal time. This persists beyond 48 hours post-breeding and causes persistent fluid accumulation within the uterus. Mares with PPBEM have an increased rate of embryonic loss and a lower overall...
Uterine blood flow and perfusion in mares with uterine cysts: effect of the size of the cystic area and age. Transrectal color and power Doppler ultrasonography was used to study uterine blood flow and perfusion in mares with and without uterine cysts. Vascular perfusion of the uterus and blood flow velocities, vascular perfusion, diameter, circumference, and area of a cross section of the mesometrial attachment were evaluated. To study the effect of internal cysts, two matched groups (cystic and control, n=21 mares/group) were used. Uterine vascular perfusion in mares with cysts was less (P<0.0001) in the cystic than the noncystic region and less (P<0.0009) than that for controls. Mares with c...
The presence of the mu-opioid receptor in the isthmus of mare oviduct. The presence of the mu-opioid receptor and the type of glycosylation in the third extra-cellular loop of this receptor was investigated in the isthmus of mare oviduct during oestrus by means of immunoblotting and immunohistochemistry combined with enzymatic (N-glycosidase F and O-glycosidase) and chemical (beta-elimination) treatments. Immunoblotting analysis showed that the mu-opioid receptor consists of two peptides with molecular weights of around 65 and 50 kDa. After N-deglycosylation with N-glycosidase F an additional immunoreactive peptide was observed at around 30 KDa. The cleavage of O...
[Evaluation of immunoglobulin G concentration in colostrum of mares by ELISA, refractometry and colostrometry]. In 360 samples of colostrum and 36 samples of blood of warmblood mares, the concentration of immunoglobulin G (IgG) was evaluated in the post partal period with an ELISA and the results were compared to values obtained with 2 field methods--refractometry and colostrometry. A significant correlation (p < 0.0001) was determined between ELISA and colostrometry (r = +0.88) and between ELISA and refractometry (r = +0.93). So both field-methods seem suitable for evaluation of the colostral IgG-concentration in mares. Further the kinetic of the IgG concentration in colostrum, the volume of colostr...
Body wall tears during late pregnancy in mares: 13 cases (1995-2006). To review management of pregnant mares with body wall defects and assess the effect of various management strategies on the outcome of mares and their foals. Methods: Retrospective case series. Methods: 13 mares. Methods: Medical records of eligible mares were reviewed. Signalment, history, admitting complaint, clinical findings, parity, type of body wall defect, concurrent diagnoses, postpartum complications, outcome of fetus, outcome of mare, and type of clinical case management were recorded. Results: 8 mares received conservative management and 5 mares received interventional management. S...
A retrospective study of artificial insemination of 251 mares using chilled and fixed time frozen-thawed semen. Historically, artificial insemination (AI) using frozen semen has been perceived to have poorer success rates and be more labour intensive than using chilled semen. A retrospective study was therefore conducted to compare the conception rate achieved by AI between chilled and frozen semen, using fixed time insemination protocols over 2 breeding seasons. Objective: Artificial insemination using chilled semen produces a higher conception rate than that achieved with frozen semen. Methods: Mares (n = 251) were inseminated with either chilled (n = 112) or frozen (n = 139) semen in the 2006 and 200...
Repeatability of preovulatory follicular diameter and uterine edema pattern in two consecutive cycles in the mare and how they are influenced by ovulation inductors. Follicular diameter is used as a guiding tool to predict ovulation in the mare. However, the great range in preovulatory follicular diameter makes prediction of optimal breeding time based on follicular diameter unreliable. Uterine edema pattern is also useful to determine the best time to breed, since intensity of edema tends to dissipate as ovulation approaches, however, not every mare follows this pattern. The aims of this study were to assess the repeatability of preovulatory follicular diameter and uterine edema pattern in two consecutive spontaneous cycles and to determine how induction ...
Follicle diameters and hormone concentrations in the development of single versus double ovulations in mares. Relationships between double ovulations and plasma hormone concentrations were compared between 18 single ovulating and 6 double ovulating mares. The study began when the first follicle reached >or=30 mm, and ultrasound scanning and blood sampling were done every 12h to Day 3 (ovulation=Day 0). Data were analyzed for 2.5 d after the largest follicle was >or=30 mm and after Day -2.5 to encompass the mean 5-d interval between a >or=30 mm follicle and Day 0. During the 2.5 d after >or=30 mm, the increasing diameter of the largest follicle was less pronounced and plasma FSH concentrati...
A study of Lusitano mare lactation curve with Wood’s model. Milk yield and composition data from 7 nursing Lusitano mares (450 to 580 kg of body weight and 2 to 9 parities) were used in this study (5 measurements per mare for milk yield and 8 measurements for composition). Wood's lactation model was used to describe milk fat, protein, and lactose lactation curves. Mean values for the concentration of major milk components across the lactation period (180 d) were 5.9 g/kg of fat, 18.4 g/kg of protein, and 60.8 g/kg of lactose. Milk fat and protein (g/kg) decreased and lactose (g/kg) increased during the 180 d of lactation. Curves for milk protein and la...
Sex preferences in Jeju pony foals (Equus caballus) for mutual grooming and play-fighting behaviors. We investigated mutual grooming by Jeju pony (Equus caballus) foals to determine whether male foals preferentially interact with potential future sexual partners or competitors. We predicted that relative to female foals, male foals would exchange grooming more frequently with young mares and that in general, foals would mutually groom more frequently with the opposite sex rather than the same sex. Observing 53 foals between April and October 1998, we recorded 113 mutual grooming events. Male foals exchanged grooming with yearling mares more frequently than with their mother, while female foal...
Effect of age on bone mineral density and micro architecture in the radius and tibia of horses: an Xtreme computed tomographic study. The effect of age on the bone mineral density and microarchitecture of the equine radius and tibia was investigated. Fifty-six bones from 15 horses aged four to 21 years were used. There were nine geldings and six mares, and none of the horses had any disease influencing bone properties. Xtreme computed tomography was used to evaluate a 9-mm segment of the diaphysis and metaphysis of each bone. The following variables were determined: length of the bone, circumference and diameter in the frontal and sagittal planes in the middle of the bone.Diaphysis: total volume, bone volume, bone volume rat...
Endometrial explant culture for characterizing equine endometritis. Endometritis after insemination is ubiquitous in the horse and is associated with semen and/or bacteria in the uterus. In up to 40% of horses, inflammation persists causing infertility. An endometrial explant culture was developed to study uterine secretion of prostaglandin F(2alpha) (PGF(2alpha)) in response to physiological and pathological challenge. Methods: Uteri were collected from mares, the endometrium dissected and explants from the uterine body or horn cultured in William's or RPMI medium. The response of explants to oxytocin, semen or bacteria compared to untreated tissue was tested...
Embryo recovery from exercised mares. The effect of exercise on mare reproductive efficiency was evaluated by comparing rates of embryo recovery from mares assigned to either an exercise regimen or a non-exercise (control) regimen. Exercised mares were worked daily for 30 min under average ambient conditions of >30 degrees C and >50% humidity. Mares were inseminated during estrus and subjected to uterine flush for embryo recovery on d 7 after ovulation for two consecutive cycles. After this, mares were allocated to the opposite group and allowed an estrous cycle without reproductive manipulation; then insemination and uterin...
Follicle and systemic hormone interrelationships during spontaneous and ablation-induced ovulatory waves in mares. The characteristics of ovulatory follicular waves were studied for spontaneous waves and waves induced during the next estrous cycle by ovarian follicle ablations and administration of PGF2alpha 10 days after ovulation in 21 mares. In the induced group, both the days of the FSH surge and day of deviation were more synchronized, LH concentrations were greater before and after deviation, estradiol concentrations were greater after deviation, and the ovulatory follicle grew at a faster rate (3.4+/-0.2 compared with 2.7+/-0.1 mm/day). The frequency of two dominant follicles/wave was not different ...
Prevalence of latent, neuropathogenic equine herpesvirus-1 in the Thoroughbred broodmare population of central Kentucky. An emerging problem of equine herpesvirus-1 (EHV-1) infection in horses in the USA is a high-mortality myeloencephalopathy that commonly occurs where large numbers of horses are stabled. EHV-1 isolates recovered from recent neurological outbreaks represent a mutant virus strain that possesses enhanced neuropathogenicity. A central question of EHV-1 myeloencephalopathy is the latency carriage rate for these mutants of EHV-1 in USA horse populations. Objective: To estimate the prevalence of neuropathogenic strains of EHV-1 as latent infections in the Thoroughbred broodmare population of central ...
