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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.
Aberrant blood flow area and plasma gonadotropin concentrations during the development of dominant-sized transitional anovulatory follicles in mares. Color Doppler transrectal ultrasound was used to evaluate blood flow area in the wall of dominant anovulatory follicles versus ovulatory follicles in mares during the transition between anovulatory and ovulatory seasons. Daily examinations were done in 11 control mares toward the end of the anovulatory season. In 13 separate mares, follicular fluid was collected from 30-mm follicles, and blood flow areas from control mares were used as a basis for designating the sampled follicle as either anovulatory or ovulatory. Blood flow area in the controls ranged from 0.18 to 0.35 cm(2) in six mares on ...
Uterine microbiology and antimicrobial susceptibility in isolated bacteria from mares with fertility problems. Uterine microbiology and antimicrobial susceptibility was investigated in 239 mares with fertility problems in a prospective study in Sweden. Uterine swab samples were collected with double guarded swabs and transported overnight before being cultured. The Minimum Inhibitory Concentrations (MIC) was determined for a panel of antimicrobials. From 152 of the 239 mares at least one bacterial species was isolated, most frequently E. coli (104 isolates), beta-haemolytic streptococci (31) and fungi (16). beta-haemolytic streptococci were more frequently (p < 0.01) associated with clinical endomet...
Comparison of ropivacaine with a combination of ropivacaine and fentanyl for the caudal epidural anaesthesia of mares. Two groups of six mares aged from eight to 18 years were anaesthetised by caudal epidural injections of ropivacaine (0.5 per cent, 0.1 mg/kg) or a combination of ripovacaine (0.08 mg/kg) and fentanyl (100 microg) in a randomised study. The onset of anaesthesia was significantly more rapid (P<0.001) and it lasted significantly longer (P<0.001) in the group anaesthetised with the combination of drugs. The surgical comfort scores of the group anaesthetised with the combination were higher than those of the group anaesthetised with ropivacaine alone (P<0.001), and the quality of intraoper...
Studies on motility and fertility of cooled stallion spermatozoa. This study on extended, cooled stallion spermatozoa aimed to compare the ability of three extenders to maintain sperm motility during 24 h of preservation, and to describe pregnancy and foaling rates after artificial insemination (AI) of stallion spermatozoa stored and transported in the extender chosen from the in vitro study. After 6 and 24 h of preservation, motility, both subjective and evaluated by the motility analyzer (total, progressive and rapid), was lower in non-fat, dried skim milk-glucose than in both other extenders: dried skim milk-glucose added to 2% centrifuged egg yolk, and u...
Degenerative endometrial changes do not change the functional capacity of immigrating uterine neutrophils in mares. An endometritis model was used to investigate the influence of degenerative endometrial changes (endometrosis) on functional parameters of uterine neutrophils in the horse. Six hours after intrauterine application of recombinant human interleukin-8 (rhIL-8), the uteri of 15 mares were flushed with phosphate-buffered saline. Quantitative and qualitative flow cytometric assays were then made to determine the absolute numbers, viability, phenotype, generation of reactive oxygen species (ROS), and phagocytic activity of immigrated polymorphonuclear neutrophilic granulocytes (PMN). Recombinant hIL-...
Differential blood flow changes between the future dominant and subordinate follicles precede diameter changes during follicle selection in mares. Diameter deviation during a follicular wave is characterized by the continued growth of the developing dominant follicle and reduced growth and regression of the subordinate follicles. This study considered the hypothesis that reduced blood flow in the future largest subordinate follicle precedes the beginning of diameter deviation. The hypothesis was tested by quantifying the daily changes in blood-flow velocities and blood-flow area within the wall of follicles before and during diameter deviation in mares (n = 7). The blood-flow end points were quantified daily by transrectal color Doppler ...
Reproductive performance of thoroughbred mares in sweden. During 1997-2001, a total of 430 Thoroughbred mares were mated by one of the two Thoroughbred stallions on a well-managed stud farm in the central part of Sweden. On arrival, a thorough gynaecological examination of all mares was performed. An early pregnancy examination was performed on days 14 and 15 after ovulation. The overall conception rates for the two stallions were 92.2 and 88.8%, and the corresponding live foal rates were 82.6 and 75.2%, respectively. The mean number of served oestrous cycles was 1.60 per mare per conception and 1.86 per live foal. The first and second cycle concepti...
Clinicopathological features of an equine ovarian teratoma. The present study describes the clinicopathological features of a mature cystic ovarian teratoma occurred in a 4 year old, cyclic, nulliparous Andalusian mare. The mass was discovered in the left ovary during a breeding soundness examination, and was hard in consistency and variously echogenic. Laparoscopy was performed to confirm the neoplastic change, followed by a unilateral laparotomic ovariectomy in the standing animal. On the cut surface the teratomatous ovary showed a large cyst filled with hair and sebaceous material and three small cysts containing mucous fluid, surrounded by solid ar...
Critical peripartum disease in the mare. The variety of diseases that occur in the peripartum mare require the examining veterinarian to evaluate the patient and the historical information carefullly so as to make an accurate diagnosis and begin appropriate therapy. An understanding of equine behavior, reproduction. mechanisms of shock,and gastrointestinal and reproductive physiology is requisite for accurate interpretation of the myriad of clinical signs of diseases present in this population. Attention to the unique metabolic and physiologic needs of the pregnant and lactating mare can aid the critical care clinician in providing o...
Alteration in uterine contractility in mares with experimentally induced placentitis. An experimental model of ascending placentitis was developed in the mare to characterize the uterine myoelectrical pattern in late gestation and determine how ascending placentitis altered this pattern. In experiment 1, myometrial electrical activity was analyzed during the early morning, late morning and evening hours in four mares in the last 15 days of gestation to identify patterns of activity. In experiment 2, nine mares received intra-cervical inoculations of Streptococcus equi subspecies zooepidemicus. Myoelectrical activity in the early morning and evening hours in these mares was comp...
Exophthalmia associated with paranasal sinus osteoma in a Quarterhorse mare. An 11-year-old Quarterhorse mare developed a paranasal sinus osteoma that extended into the right orbit and led to ipsilateral exophthalmia. Although the tumor was radiographically evident in the paranasal sinuses, ultrasonography was used to demonstrate extension of the tumor into the retrobulbar space, and endoscopy was used to identify its extension into the nasopharynx. Biopsies were obtained using both fine-needle aspiration and paranasal sinus trephination. Despite numerous antemortem diagnostic tests, only postmortem histologic analysis of the mass afforded the diagnosis of osteoma.
Placental teratocarcinoma in a mare with possible metastasis to the foal. A teratocarcinoma was diagnosed in the amnion of a 5-year-old Arabian mare that delivered a healthy, full-term foal. The foal died at 2.5 months of age as a result of metastasis of an undifferentiated component of the mass. This case is unique because it is the first reported case of placental teratocarcinoma in animals and the malignant component apparently metastasized to the foal resulting in its death.
Physiological and pathological expression of intermediate filaments in the equine endometrium. The aim of this study was to investigate the expression of the intermediate filaments cytokeratin, vimentin and desmin in the equine endometrium by immunohistological techniques. For this purpose, endometrial biopsies of 151 mares were examined to determine physiological cycle patterns and changes resulting from endometriosis. During the physiological cycle epithelial cells and mesenchymal cells express cytokeratin and vimentin, respectively, whilst desmin and vimentin were coexpressed by the smooth muscle cells. Epithelial coexpression of cytokeratin and vimentin was seen in numerous fibrotic...
Nonpharmacological suppression of oestrus in the mare. The maintenance of luteal function is essential for the
establishment of pregnancy in all mammals. While the lifespan of
the corpus luteum (CL) is independent of the presence of a
conceptus in carnivores (Lawson and Findlay 1977), prolongation
of luteal function in polyoestrous animals requires the presence of
the conceptus to defuse and suppress the cyclical luteolytic
mechanism in the nonpregnant state (Short 1969). In the horse, the
conceptus remains spherical and unattached (Van Niekerk and
Allen 1975) after it enters the uterus between 144 and 168 h after
ovulation (Battut et al....
In vitro maturation and transfer of equine oocytes after transport of ovaries at 12 or 22 degrees C. Transportation of equine ovaries would allow shipment of oocytes for research purposes or transfer after the death of a valuable mare. The objective of this study was to compare two temperatures for maintaining ovaries during a transport interval of 18-24 h. The goal was to obtain pregnancies after transport of ovaries, maturation of oocytes in vitro, and transfer of oocytes. Each shipment was composed of ovaries four to seven mares collected from an abattoir. From each mare, one ovary was packaged at approximately 12 degrees C, and the other was packaged at approximately 22 degrees C. Upon ar...
Interrelationships of estradiol, inhibin, and gonadotropins during follicle deviation in pony mares. The changes in circulating concentrations of FSH, LH, estradiol, and total inhibin associated with the beginning of follicle diameter deviation were compared among the last anovulatory follicular wave of the year and the first and second ovulatory waves in pony mares ( n=7 ). Follicle diameters and circulating hormone concentrations for each wave were normalized to the observed beginning of deviation (Day 0). Follicle deviation was demonstrated during the anovulatory wave as well as during the ovulatory waves, and the diameter of the future dominant follicle at the beginning of deviation was s...
Ultrasonic characteristics of preovulatory follicle and ovulation in Caspian mares. The Caspian breed of horses is believed to be the direct descendant of the earliest equine animals. Some special characteristics of Caspian horse differentiate this breed of horses from other breeds. In the current study the ultrasonically observed characteristics of a preovulatory dominant follicle and the lengths of estrus, diestrus as well as some related parameters were studied during 42 interovulatory intervals in 11 healthy Caspian mares. The preovulatory dominant follicle deviated from subordinate follicles and became the largest follicle in the ovaries at Day -8.7 +/- 0.53 (Day 0=ovula...
The effect of exogenous estradiol benzoate and altrenogest on uterine and ovarian blood flow during the estrous cycle in mares. In recent years, a positive relationship between genital perfusion and fertility has been established; in species other than horses, uterine and ovarian perfusion was improved by exogenous estrogen but impaired by exogenous progestin. The goal of the present study was to investigate the effect of exogenous estrogen and progestin on uterine and ovarian blood flow in cycling mares. Five Trotter mares were examined daily during three estrous cycles. Mares were given no treatment, altrenogest (0.044 mg/kg BW) orally from Day 0 (ovulation) to Day 14 and estradiol benzoate (5mg i.m.) on Days 0, 5, a...
Pregnancy rates of mares inseminated with semen cooled for 18 hours and then frozen. The ability to ship cooled stallion sperm for subsequent freezing at a facility specializing in cryopreservation would be beneficial to the equine industry. Stallion sperm has been centrifuged, cooled to 5 degrees C for 12 h, and frozen without a detrimental effect on motility in a previous study; however, no fertility data were available. Experiment 1 compared the post-thaw motility of sperm cooled for 18 h at 15 or 5 degrees C at either 400 or 200 x 10(6) sperm/mL and then frozen. Storage temperature, sperm concentration, or the interaction of temperature and concentration had no effect on t...
Cholelithiasis associated with recurrent colic in a Thoroughbred mare. A 13-year-old Thoroughbred mare, retired from race, was admitted to Equine Hospital, Korea Racing Association with signs of colic. One and a half months following the previous treatment (second time) and 11 days following her previous discharge (third time), the mare repeatedly exhibited signs of colic and finally along with icteric eyes. Routine medical treatment with intravenous fluids, analgesics resulted in resolution of signs of colic in the first and second admission. The condition of the mare did not improve in the third admission despite over one month supportive treatment and she was ...
Headshaking in a 10-year-old Thoroughbred mare. A 10-year-old Thoroughbred mare was presented with a 2.5-week history of headshaking. Based on a thorough physical examination, blood analysis, and a fine needle aspirate of an enlarged thyroid gland, a tentative diagnosis of seasonal idiopathic headshaking was made. Treatment with cyproheptadine was attempted. Une jument Thoroughbred âgée de 10 ans a été présentée pour un problème d’encensement qui durait depuis 2.5 semaines. Suite à un examen physique méticuleux, à une analyse de sang et à un prélèvement par aspiration à l’aiguille de la glande thyroïde hypertrophiée, un...
Eastern tent caterpillars (Malacosoma americanum) cause mare reproductive loss syndrome. A new equine abortigenic disease, mare reproductive loss syndrome (MRLS), was recognized and significantly impacted the Ohio Valley in the springs of 2001 and 2002. MRLS caused approximately 330 million US dollars in losses in 2001. An epidemiological investigation of MRLS associated occurrence of the disease with exposure to eastern tent caterpillars (M. americanum). This work investigates the epidemiological association between M. americanum and MRLS to determine if this association was correlative or causative. A pilot study and simulated exposure to M. americanum and their excreta on pastu...
Immunogenecity of synthetic peptides representing linear B-cell epitopes of VapA of Rhodococcus equi. Amino acid 65-78 of membrane protein VapA of the facultative intracellular Rhodococcus equi contained an immunodominant N-terminal B-cell epitope (N15Y peptide). Safety and immunogenecity of a synthetic peptide consisting of the amino acid 65-78 of VapA (peptide N15Y) were evaluated first in mice and in healthy adult horses. A single dose of a peptide-VapA vaccine induced and only in presence of adjuvant, specific IgG antibodies in sera of mice. After challenge with virulent R. equi 3 weeks after immunization, tissue clearance was more delayed in immunized mice than in control mice. An antibod...
Standing female equine urogenital endoscopic surgery. 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...
Dorsally recumbent female equine urogenital endoscopic surgery. The ventral abdominal approach for laparoscopy is versatile. Reported techniques using a ventral approach in the mare include bilateral ovariectomy and granulosa cell tumor removal. Laparoscopic ovariectomy is performed by way of four instrument portals in the caudoventral aspect of the insufflated abdomen. The procedure has several advantages over the traditional approaches of colpotomy and celiotomy, including tension-free closure of all incisions and minimal invasiveness.
Concentrations of gentamicin in serum and bronchial lavage fluid after once-daily aerosol administration to horses for seven days. To assess gentamicin concentrations in serum and bronchial lavage fluid (BLF) of horses during a 24-hour period after once-daily aerosol administration of gentamicin (GAER) for 7 days and the pattern and degree of bronchial tree inflammation associated with repeated GAER. Methods: 13 healthy adult horses (9 geldings and 4 mares). Methods: The treatment group comprised 8 horses, and 5 horses were untreated control animals. Gentamicin (20 mL of gentamicin [50 mg/mL]) was administered via aerosol once daily for 7 days. Samples of serum and BLF were obtained from all horses before GAER and 0.5, 4,...
Detection of equine herpesvirus 3 in equine skin lesions by polymerase chain reaction. During a recent breeding season, ulcerative, pustular skin lesions were observed on the external genitalia of 2 mares and 1 stallion within a small herd. Based on the location and description of the skin lesions plus the clinical history, equine coital exanthema, caused by equine herpesvirus 3 (EHV3), was the primary differential diagnosis. Scrapings of skin lesions from the perineum of 2 mares were submitted for diagnostic evaluation. Virus isolation was attempted by inoculation of several cell lines of equine origin, but no cytopathic agent was detected. The skin scrapings were processed for...
Absence of effects from immunocontraception on seasonal birth patterns and foal survival among barrier island wild horses. Despite a large body of safety data, concern exists that porcine zonae pellucidae (PZP) immunocontraception--used to manage wild horse populations--may cause out-of-season births with resulting foal mortality. Our study at Assateague, Maryland indicated the effects of immunocontraception on season of birth and foal survival between 1990 and 2002 on wild horses from Assateague Island. Among 91 mares never treated, 69 (75.8%) of foals were born in April, May, and June (in season). Among 77 treated mares, 50 (64.9%) were born in season. Of 29 mares foaling within 1 year after treatment (contracep...
Effect of active immunization of pony mares against recombinant porcine inhibin alpha subunit on ovarian follicular development and plasma steroids and gonadotropins. Two pony mares were immunized against recombinant porcine inhibin alpha subunit three times with 39 day intervals. Clinical findings and endocrinological changes before immunization were taken as the control. The first significant rise in the anti-inhibin titre (P<0.05) in the circulation was found 27 days after the first injection. Maximum binding activity was reached by the 12th day after the second booster dose. The number of small, medium and large sized follicles had increased significantly compared to before immunization (11.75 +/- 4.30, 2.75 +/- 0.69 and 2.51 +/- 0.63 vs 6.50 +/- 1.4...
Treatment of suckling beef cattle with a progestagen sponge and oestradiol benzoate or equine chorionic gonadotrophin. The ovarian responses of anoestrus beef cows to a combined treatment with medroxy-progesterone acetate (MAP) sponges and oestradiol benzoate or equine chorionic gonadotrophin (eCG) were evaluated. Forty-five suckling Hereford cows were allocated to three equal groups. Group 1 received a MAP sponge for seven days plus an injection of 2 mg oestradiol benzoate when the sponge was inserted (day 0) and 1 mg when the sponge was withdrawn; group 2 received identical treatment until day 7, when a dose of 400 iu of eCG was administered, and group 3 were left untreated as control animals. From day 0 to ...
