Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
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.
Recovery of horses from general anesthesia in a darkened or illuminated recovery stall. To assess whether recovery from general anesthesia, in an illuminated or a darkened stall, has an effect on time to first movement, time to standing, and recovery score. Methods: Prospective randomized clinical study. Methods: Twenty-nine healthy, 2- to 5-year-old horses undergoing surgical correction of dorsal displacement of the soft palate. Methods: Each horse was assigned randomly to recover in either an illuminated (n = 15) or a darkened stall (n = 14). For pre-anesthetic medication, all horses received intravenous (IV) xylazine (0.4 mg kg(-1)) and butorphanol (0.02 mg kg(-1)). Anesthesia...
Seasonal effects on the response of ovarian follicles to IGF1 in mares. The response of follicles to IGF1 was compared between the transition into the ovulatory season (transitional period) and the ovulatory season (ovulatory period) in eight mares using a cross-over experimental design within periods. Granulosa cells were collected from follicles 15-24 or 25-34 mm and expression of IGF1R, IGF2R, FSHR, LHCGR and PAPPA was determined by qPCR. In addition, 10 mg IGF1 or vehicle were injected into the largest follicle (transitional period) or the second largest follicle (ovulatory period) of a follicular wave before the beginning of diameter deviation between the two...
Kisspeptin immunoreactive neurons in the equine hypothalamus Interactions with GnRH neuronal system. To determine if kisspeptin could be implicated in the control of reproduction in equine species, we studied the distribution of kisspeptin neurons and their anatomical interactions with GnRH neurons in the hypothalamus of pony mares. Brains were collected in three pony mares between 2 and 4h after ovulation. One major population of kisspeptin immunoreactive cell bodies was found in the arcuate nucleus (ARC), where they extended from the middle of the nucleus to the premammillary recess. Kisspeptin immunoreactive varicose fibers extended from the preoptic area to the mammillary nuclei, with imp...
Acute lead intoxication in a pregnant mare. Lead (Pb) intoxication in horses is usually a chronic phenomenon with clinical signs associated with central nervous dysfunction. This report gives details of a case of acute Pb intoxication in a 9-year-old American Saddlebred mare with severe, progressive and ultimately fatal neurological deterioration. During the 4 days of hospitalisation, clinical signs progressed from intermittent headshaking and depression to severe, continuous, uncontrollable manic behaviour. At autopsy, three grey-coloured, hard metal particles were present in the gastrointestinal tract and subsequently found to contain...
Oestrogens in faeces as an indicator of the foeto-placental unit function in mares. Total of 30 pregnant mares were used in this study: 17 Thoroughbred and 13 Primitive Polish Horse. The concentration of total unconjugated oestrogens was determined by radioimmunoassay in faecal samples obtained every second week after mating until delivery or interruption of pregnancy. Concentration of oestrogens in pregnant healthy mares ranged from 40 to 200 ng/g and showed typical profiles for pregnancy. In 5 of 30 mares (16.6%) of either breed abortions and cases of embryonic death occurred. Abortions were preceded by sharp or gradual decrease in oestrogen concentration, whereas prior to ...
The use of electrochemically activated saline as a uterine instillation in pony mares. Twelve pony mares were randomly assigned to either a control or a treatment group and inseminated with fresh, raw semen from a single stallion of known fertility in a cross-over trial design. Pregnancy was diagnosed by transrectal ultrasound 12-14 days post-ovulation and then terminated by administration of a luteolytic dose of cloprostenol. Treatment mares received a uterine instillation of 100 ml of electrochemically activated (ECA) saline 4-12 hours post-insemination. Control mares received no treatment post-insemination. Per cycle pregnancy rate was 58.3 % in the control group and 50 % in ...
Characterisation of pulses of 13,14-dihydro-15-keto-PGF2alpha (PGFM) and relationships between PGFM pulses and luteal blood flow before, during, and after luteolysis in mares. Blood collections for characterising 13,14-dihydro-15-keto-PGF2alpha (PGFM) pulses in mares and colour-Doppler examinations for estimating percentage of corpus luteum with blood-flow signals were done hourly for a 24-h session on Day 15 (ovulation = Day 0; n = 13 mares) or during 12-h sessions from Days 12 to 16 (n= 10 mares). Luteolysis was defined as extending from the beginning of a precipitous decrease in progesterone until progesterone was <2 ng mL(-1). Comparisons were made among preluteolysis, luteolysis, and postluteolysis. Greater prostaglandin F2alpha activity (mean PGFM concentra...
Klebsiella oxytoca as a cause of equine abortion–short communication. Klebsiella (K.) oxytoca infection induced the abortion of a female equine fetus in the 10th month of pregnancy. Bacteria were cultured from the liver, lung and stomach content. They were labelled with an anti-Mycobacterium bovis antibody in the thymus, liver and lungs and were stained with Giemsa and Brown-Brenn staining in the thymus and lung. The diffusely consolidated lungs contained numerous grey-whitish foci 2-4 mm in diameter, which corresponded to severe pyogranulomatous pneumonia characterised by numerous intraalveolar neutrophils and macrophages and multinucleated Langhans' giant cell...
Use of a low dose of equine purified FSH to induce multiple ovulations in mares. The effects of a low dose of equine purified FSH (eFSH) on incidence of multiple ovulations and embryo recovery rate in mares were studied. During the physiological breeding season in Brazil (19 degrees 45'45'S), 14 Mangalarga Marchador donor mares were used in a crossover study and another 25 mares of the same breed, between 3 years and 12 years of age were used as recipients for the embryo transfers. Donors were monitored during two consecutive oestrus cycles, an untreated control cycle followed by a treated cycle, when eFSH was administered. In both cycles, after an embryo collection attemp...
Embryo transfer induces a subclinical endometritis in recipient mares which can be prevented by treatment with non-steroid anti-inflammatory drugs. We tested the hypothesis that subclinical endometritis occurs after embryo transfer (ET) in the horse. Recipient mares were treated with meclofenamic acid (M) or flunixin meglumin (F) after ET or were left untreated (n=9 per group). Embryos were re-collected 4 days after transfer. Endometrial biopsies were taken for histology and analysis of cyclooxygenase-2 (COX-2) by immunohistochemistry and for PCR. Bacteriological swabs were collected from the uterus and lavage fluid of donor and recipient mares. Progesterone and prostaglandin F(2alpha) release was analysed in recipient mares after ET. Fou...
Mechanisms for dominant follicle selection in monovulatory species: a comparison of morphological, endocrine and intraovarian events in cows, mares and women. The selection of a single ovarian follicle for further differentiation and finally ovulation is a shared phenomenon in monovulatory species from different phylogenetic classes. The commonality of dominant follicle (DF) development leads us to hypothesize that mechanisms for DF selection are conserved. This review highlights similarities and differences in follicular wave growth between cows, mares and women, addresses the commonality of the transient rises in FSH concentrations, and discusses the follicular secretions oestradiol and inhibin with their regulatory roles for FSH. In all three spe...
Proteins associated with the early intrauterine equine conceptus. A critical period of early gestation in the mare involves the immobilization (fixation) of the encapsulated conceptus at around days 16-17. We compared the major proteins in the normal equine embryonic capsule and endometrial secretions around the period of fixation with those from pregnancies in the process of termination induced by administration of an analogue of prostaglandin F(2 alpha) (PGF(2 alpha)). Uterocalin and beta(2)-microglobulin (beta(2)M) associated with the embryonic capsule were proteolytically converted to smaller forms during the fixation period. These conversions were simil...
Follicle development in mares. The mare provides a unique experimental model for studying follicle development in monovular species. Development of antral follicles in horses is characterized by the periodic growth of follicular waves which often involve the selection of a single dominant follicle. If properly stimulated, the dominant follicle will complete development and eventually ovulate a fertile oocyte. Regulation of follicular wave emergence and follicle selection involves an interplay between circulating gonadotropins and follicular factors that ensures that individual follicles are properly stimulated to grow (or t...
The use of dexamethasone administered to mares at breeding time in the modulation of persistent mating induced endometritis. The present study describes the effect of a single dose of dexamethasone administered to mares at time of breeding. In an initial experiment, the authors investigated safety of treatment. In a second experiment the effect of treatment on the uterine environment, fetal development and pregnancy outcome was examined. In the final part of the study, mares susceptible to persistent mating induced endometritis were identified, by means of a risk factor score system and the effect of treatment evaluated. Results indicated that dexamethasone administered at breeding time did not negatively impact on ...
Surgical treatment of uterine torsion using a ventral midline laparotomy in 19 mares. To report on the outcome of surgical treatment of uterine torsion in preterm mares. Methods: Retrospective case series of pregnant mares with uterine torsion presented to the Clinic for Obstetrics, Gynaecology and Andrology of Large and Small Animals. Methods: Hospital records of all pregnant mares that underwent ventral midline laparotomy for uterine torsion between 1998 and 2004 were reviewed. The signalment, history, clinical signs, results of diagnostic procedures, direction and degree of the uterine twist, treatment and outcome were retrieved from each case record. Results: This study com...
Treatment with a High Dose Combination of PMSG/hCG Preparation of Mares Clinically Diagnosed with Ovarian Quiescence during the Breeding Season (Investigation from 1975 to 2000). A total of 88 thoroughbred mares were diagnosed with clinical ovarian quiescence and subjected to four treatment regimens. Using PMSG, hCG or combinations of both. A high dose combination of 5,000IU PMSG with 5,000IU hCG showed significantly higher rates of marked estrus and ovulation induction (P<0.01) as well as conception rates (P<0.05). In the present study, the administration of a high-dose combination of PMSG with hCG was shown to be an effective treatment of ovarian quiescence in light mares.
Intrafollicular Concentrations of Steroid Hormones and PGF2α in Relation to Follicular Development in the Mares during the Breeding Season. The concentrations of androstenedione, estradiol-17β, progesterone and PGF2α contained in the follicular fluid produced by the follicles in collected ovaries of mares that have had estrous phase during the breeding season were measured and analyzed the relation between the growth stage of follicles and the hormone levels in the follicular fluid. An ultrasonographic diagnostic instrument was used to measure the diameter of the follicles in order to categorize the follicles into three groups the following: 8 small follicles (from 1.0 to less than1.5 cm), 8 medium follicles (from 1.5 to less th...
Expression of anti-Müllerian hormone (AMH) in equine granulosa-cell tumors and in normal equine ovaries. Anti-Müllerian hormone (AMH), also known as Müllerian inhibiting substance (MIS), is expressed by granulosa cells in females of many mammalian species, and circulating AMH concentrations have been used to monitor granulosa-cell tumors (GCT) in women. The objective was to characterize expression of AMH in equine GCT, and in normal equine ovaries, based upon immunohistochemistry (IHC), using a polyclonal primary antibody directed against human AMH. Equine GCT (n=27) and normal equine ovaries (n=10) were examined by IHC. In addition, sera from four mares with GCT were characterized for AMH bioa...
Surgical technique to repair grade IV rectal tears in post-parturient mares. To describe a surgical technique for repair of grade IV rectal tears after parturition in mares and to report outcome. Methods: Clinical report. Methods: Horses (n=6) with grade IV rectal tears. Methods: Mares were sedated and restrained in standing stocks. After caudal anesthesia and evacuation of feces from the rectum, the perineal region was aseptically prepared. Four stay sutures were placed through the external anal sphincter before vertical transection (12 o'clock). Caudal retraction of the tear was performed using Allis tissue forceps (5 mares) or stay sutures before accurate apposition...
Induction of estrus and ovulation: why some mares respond and others do not. The two most common procedures for breeding management of mares involve induction of luteolysis and induction of ovulation. Although both of these events are usually achieved, physiologic conditions affect the timing of the response. In a diestrus mare treated with prostaglandin F(2alpha) (PGF), or a PGF analogue, it is well documented that, on average, the interval from treatment to the onset of estrus is 3-4 days, whereas ovulation occurs 8-10 days after treatment. However, the diameter of the ovulatory follicle, as well as its status at the time of PGF treatment, determines the intervals fr...
Gonadotropin-dependent regulation of the prostaglandin E2 receptor in equine preovulatory follicles during the ovulatory process in mares. The objectives of the study were to clone the primary structure of the prostaglandin E2 receptor subtype 2 (PTGER2) cDNA and to characterize its regulation in equine follicles during gonadotropin-induced ovulation. Results from DNA isolation indicated that the equine PTGER2 cDNA encodes a predicted 353-amino acid protein, which is highly similar (76-85%) to known mammalian homologues. The regulation of PTGER2 was studied by semi-quantitative RT-PCR/Southern blot using preparations of theca interna and mural granulosa cells isolated from equine follicles 0-39 hr post-treatment with human chorio...
Optimizing the use of frozen-thawed equine semen. This manuscript is a review of current protocols, advantages, and disadvantages of breeding mares with frozen-thawed equine semen. Issues affecting pregnancy rates are discussed, including proper mare selection, induction of ovulation, insemination dose, timing of insemination (single-dose versus multiple-dose insemination), methods of insemination (transrectal-guided deep-horn versus hysteroscopic insemination), and post-insemination mare management procedures. In a retrospective analysis of breeding records, a single-dose of frozen-thawed semen was inseminated within 6h post-ovulation; the p...
Immunolocalisation of the uterine secretory proteins uterocalin, uteroferrin and uteroglobin in the mare’s uterus and placenta throughout pregnancy. Previous studies have shown that the equine uterus produces many progesterone-dependent proteins throughout gestation. In particular, uterocalin and uteroferrin are detectable using electrophoresis or blot analyses but information regarding the immunohistochemical placental distribution of these two proteins is rare and information regarding uteroglobin is still lacking. The aim of the present study was to co-immunolocalise these three secretory proteins in the mare's uterus throughout gestation in an effort to understand their functional role in the maintenance of pregnancy. Therefore, endome...
When should a mare go for assisted reproduction? The use of assisted reproductive techniques (ART) has helped owners to produce offspring from valuable mares that were considered infertile using standard breeding techniques. Before referring a mare for an ART, the practitioner should be able to identify the underlying cause of subfertility of the mare. The objective of this review is to provide information regarding embryo transfer, oocyte transfer and intracytoplasmic sperm injection, the three most common ART used in equine practice. Knowing the complexity as well as the risks of these techniques, enables practitioners to refer a subfertil...
Prevalence of gastric ulcers in Thoroughbred broodmares in pasture: a preliminary report. Gastroscopic examinations were performed in 62 Thoroughbred broodmares (33 pregnant, 29 non-pregnant) at one breeding farm to investigate the prevalence of gastric ulceration. Age, pregnancy status, race earnings, last race start, herd size, medical history, number of live foals, breeding years, feed type and number of feedings were recorded, plus coat condition and body condition score were determined. Twenty-one mares were re-evaluated after foaling, and the foaling date, foal weight at birth and placenta weight were recorded. The overall prevalence of gastric ulcers was 70.9%, with a median...
When to refer an infertile mare to a theriogenologist. Most equine infertility cases can be solved with a methodical, thorough physical and reproductive examination and appropriate diagnostic laboratory aids. Repeated examinations may be needed in some cases to identify subtle anatomical abnormalities or irregularities between hormonal and physiological relationships of the reproductive tract. For pregnancy to occur, hormonal signaling must be exquisitely synchronized with physical changes of the reproductive tract and deposition of fertile semen in the uterus. Asynchrony of these events, infection, inflammation, previous trauma to the reproductiv...
The diagnosis and treatment of endometritis in the mare: yesterday and today. Diagnosis and treatment of endometritis in the mare has been controversial and mostly empirical. The lack or inability of researchers to establish or develop a model that can serve as a standard or control makes this area of equine reproduction difficult to address scientifically. However, major advances have been made, particularly with the demonstration of the importance of uterine contractility in the elimination of bacteria, fluid, and inflammatory products from the uterus after breeding. This review provides a historical perspective of what has been done, and where we are now, in the appr...
Relationship between peripartal plasma oxytocin and prostaglandin F(2alpha) metabolite and placental expulsion time in heavy draft mares. The aim of this study was to clarify the relationship between circulating oxytocin (OT) and PGF(2alpha) metabolite (PGFM) in mares at the third stage of labor and placental expulsion time in order to investigate a cause of retained placenta of which the incidence increase in a heavy draft mare. Blood was sampled every 5 min from foaling to expulsion of the placenta in 18 heavy draft mares to evaluate circulating OT and PGFM. The relationships between OT and PGFM concentration and recorded placental expulsion times were investigated. The results were as follows (1) The highest level of OT conce...
Transvaginal ultrasound-guided aspiration of unilateral twin gestation in the mare. Embryo reduction of unilateral twin vesicles is normally successful before fixation of the vesicles. After fixation, however, it becomes a challenge, and the later in the gestation period that the reduction is performed, the greater the challenge. One therapy to reduce a twin into a singleton pregnancy is the transvaginal ultrasound-guided aspiration (TUGA) of one of the vesicles. The results of 35 unilateral twin reductions by TUGA are discussed in this paper and possible negative influences of age, parity and days pregnant are analysed statistically.
A clinical approach to managing the mare with placentitis. Placental infections in the mare are a diagnostic and therapeutic challenge. The following article will review techniques for identifying placental infections, approaches for treating placentitis, and methods for managing these mares after foaling.
