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.
Briant C, Toutain PL, Ottogalli M, Magallon T, Guillaume D.The appropriate dosage regimen for equine FSH (eFSH) (dose, dosing interval) administration in a superovulation treatment in pony mares was determined by a kinetic approach using production rates and kinetic parameters of elimination of the hormone. Two dosage regimens were then tested in superovulation protocols. The eFSH production rates were determined by sampling four ovariectomized pony mares every 10 min for 8 h during the breeding season. Kinetic parameters were determined by administering four dose levels of a preparation of eFSH (4.4, 8.8, 17.6 and 35.2 micro g/kg) by the i.v. route t...
Ousey JC.The endocrine profiles in the periparturient mares are dominated by increasing concentrations of progestagens and decreasing oestrogens. These hormones are produced by precursors from the foetus, metabolized by the placenta and act primarily on the maternal uterus. The circulating concentrations of hormones in maternal plasma, generally, represent a small proportion of those metabolized by the foetus and utero-placental tissues. There is clear evidence that the foetal hypothalamo-pituitary-adrenal (HPA) axis initiates the process of foetal maturation and the hormonal cascade which culminates i...
Briant C, Ottogalli M, Guillaume D.With the objective of controlling the day of ovulation, 40 mares were assigned to a control or three treated groups: A3d, A4d, and A5d. The treated groups received antarelix (Teverelix 0.01 mg/kg, i.v., twice a day) for 3, 4, or 5 days from the day the dominant follicle (F1) reached 28 mm (=D0), and one injection of hCG (1600 IU, i.v.) on D1, D2, or D3, respectively. Control mares received one injection of hCG when F1 reached 35 mm. Plasma LH, FSH, progesterone, and total estrogens were assayed. In the A3d, A4d, and A5d groups, 9 (90%), 6 (60%), and 5 (50%) out of 10 mares, respectively, ovula...
Dell'Aquila ME, Caillaud M, Maritato F, Martoriati A, Gérard N, Aiudi G, Minoia P, Goudet G.The aim of this study was to investigate cumulus expansion, nuclear maturation and expression of connexin 43, cyclooxygenase-2 and FSH receptor transcripts in equine cumuli oophori during in vivo and in vitro maturation in the presence of equine FSH (eFSH) and precursors for hyaluronic acid synthesis. Equine cumulus-oocyte complexes (COC) were cultured in a control defined medium supplemented with eFSH (0 to 5 micrograms/ml), Fetal Calf Serum (FCS), precursors for hyaluronic acid synthesis or glutamine according to the experiments. After in vitro maturation, the cumulus expansion rate was incr...
Chopineau M, Martinat N, Gibrat JF, Galet C, Lecompte F, Foulon-Gauze F, Pourchet C, Guillou F, Combarnous Y.To identify amino-acids in the alpha-subunit important for expression of heterospecific FSH activity of horse (e) LH/choriogonadotropin (CG) (eLH) and donkey (dk) LH/CG (dkLH) (FSH/LH ratio ten times higher for eLH than for dkLH); this FSH activity absolutely requires an equid (donkey or horse) alpha-subunit combined with an equid beta-LH subunit. Methods: Chimeric alpha-subunits possessing the first 63 amino-acids of the porcine (p) and the last 33 amino-acids of the donkey alpha-subunit (alphap-dk) and the inverse (alphadk-p) were constructed. Porcine-specific amino-acids were introduced by ...
Ginther OJ, Gastal EL, Gastal MO, Bergfelt DR, Baerwald AR, Pierson RA.Deviation in growth rates of the follicles of the ovulatory wave begins at the end of a common growth phase and is characterized by continued growth of the developing dominant follicle (F1) and regression of the largest subordinate follicle (F2). Follicle diameters during an interovulatory interval were compared between 30 mares and 30 women, using similar methods for collecting and analyzing data. Follicles were tracked and measured daily by ultrasonography. Diameter at follicle emergence (mares, 13 mm; women, 6 mm) and the required minimal attained diameter for assessment of follicles (mares...
Eroksuz H, Eroksuz Y, Ozer H, Ceribasi AO, Yaman I, Ilhan N.Naturally occurring goiter cases are described in 2 newborn Arabian foals whose mares were supplemented with excess iodine during the final 24 w of the pregnancy. Six nursing foals and 2 mares were also affected clinically with thyroid hypertrophy. At least 12 times the maximum tolerable level of iodine supplementation was given, as the daily iodine intake for each mare was 299 mg. The prevalence of goiter cases was 2 and 9% in the mares and foals, respectively.
Wittek T, Sobiraj A.In the present study the concentrations of L-carnitine (total carnitine, free carnitine, and acyl carnitine) and several parameters of the lipid metabolism were measured during the estrus in 10 broodmares. The carnitine concentrations varied in a wide range between the mares. The differences of the mean carnitine concentrations during the estrus did not reach the level of significance (P < 0.05). There was no relationship between the concentrations of total and free carnitine to the follicle size; however, the concentration of acyl carnitine was significantly correlated (r = -0.42). Because...
Glazar BS, McCue PM, Bruemmer JE, Squires EL.Practical estrus synchronization schemes are needed for mares. The Ovsynch synchronization protocol for cattle involves the administration of gonadotropin-releasing hormone (GnRH) to induce ovulation or luteinization of dominant follicles during the luteal phase and prostaglandin 7 days later to cause regression of any luteal tissue and development of a preovulatory follicle. An Ovsynch-type synchronization program potentially could be developed for horses if luteinization or ovulation of diestrous follicles occurred in response to GnRH treatment. The objective of this study was to determine i...
Stoica G, Cohen N, Mendes O, Kim HT.Mesotheliomas are rarely reported in animal species. In this report, the occurrence of a diffuse, metastatic mesothelioma in a 6-year-old gray Arabian mare is described. The mare was presented on clinical examination with ascites, bilateral pleural effusion, and pleural roughening. Necropsy revealed abundant fluid in the abdominal and thoracic cavities. The surface of all organs was thick and fibrosed with multiple raised nodules and hemorrhages. Histology was characteristic of a generalized, biphasic mesothelioma with vascular and lymph nodes metastases. It is believed that the primary tumor ...
Alghamdi AS, Foster DN, Troedsson MH.Seminal plasma (SP) is known to have immunosuppressive properties in several species. Equine SP has been reported to reduce or inhibit chemotaxis, phagocytosis and complement activity in vitro. The type and amount of the SP component that suppresses sperm-polymorphonuclear neutrophil (PMN) binding in vitro was determined, and the effect of such suppression on the fertility of mares inseminated in the presence of uterine inflammation, was analyzed. Sperm cells were suspended in either SP, semen extender or a mixture of both, and each was mixed with PMN-rich uterine secretions collected at 12 h ...
Orsini JA, Baird DK, Ruggles AJ.A 7-year-old female Thoroughbred was admitted with a history of labored breathing, stridor, and exercise intolerance. Examination revealed a mass in the left paranasal sinuses that was determined to be an ossifying fibroma. Initial treatment consisted of surgical removal of the mass alone; however, the mass recurred 9 months after surgery. The mass was again removed, and adjunctive radiotherapy consisting of 3,000 cGy of cobalt radiation was administered. This time, the tumor did not recur for > 6 years. A third surgery was performed to remove the mass, and adjunctive radiotherapy consisting o...
Komáromy AM, Andrew SE, Brooks DE, Detrisac CJ, Gelatt KN.A periocular nodular sarcoid of the right upper and lower eyelids was diagnosed in an 11-year-old Thoroughbred mare. Computed tomography scan revealed the extent of the tumor. The mass was surgically debulked under general anesthesia, and the affected periocular region was injected intralesionally with Bacillus of Calmette and Guerin (BCG). An emulsion of cell wall fractions was used, which has been modified to reduce the toxic and allergic effect, but retain the antitumor activity. In total, five injections were performed at 2-week intervals. At follow-up 7 months after the last BCG injection...
Foote CE, Gilkerson JR, Whalley JM, Love DN.To examine the prevalence of equine herpesvirus 1 antibody in mares and foals on a large Hunter Valley Thoroughbred stud farm in New South Wales before and after the introduction of an inactivated whole virus vaccine. Methods: Cross-sectional serological surveys performed in February 1995 and 2000 to determine the prevalence of EHV-1 antibody-positive mares and foals. A further cross-sectional survey was carried out in 2001 to complement the 2000 data. Methods: Two hundred and twenty-nine mares and their foals were sampled in 1995 and 236 mares and their foals were sampled in 2000. The study p...
Acosta TJ, Beg MA, Ginther OJ.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 ...
Albihn A, Båverud V, Magnusson U.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...
Ganidagli S, Cetin H, Biricik HS, Cimtay I.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...
Rota A, Furzi C, Panzani D, Camillo F.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...
Zerbe H, Engelke F, Klug E, Schoon HA, Leibold W.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-...
Acosta TJ, Gastal EL, Gastal MO, Beg MA, Ginther OJ.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 ...
Hemberg E, Lundeheim N, Einarsson S.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...
Catone G, Marino G, Mancuso R, Zanghì A.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...
Dolente BA.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...
McGlothlin JA, Lester GD, Hansen PJ, Thomas M, Pablo L, Hawkins DL, LeBlanc MM.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...
Scotty NC, Ford M, Williams F, Loiacono C, Johnson PJ, Messer NT, Turnquist SE, Essman S.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.
Allison N, Moeller RB, Duncan R.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.
Aupperle H, Schoon D, Schoon HA.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...
Lefranc AC, Allen WR.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....
Preis KA, Carnevale EM, Coutinho da Silva MA, Caracciolo di Brienza V, Gomes GM, Maclellan LJ, Squires EL.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...
Vandeplassche M, Bouters R, Spincemaille J, Bonte P.Eight cases of severe dropsy of the fetal sacs have been observed in mares. All were in multiparous mares whose ages ranged from five to 20 years and who were 7 1/2 to 10 3/4 months pregnant. Abortion started spontaneously in four cases and had to be induced in the remaining four by manual dilation of the cervix, rupture of the tough allantochorion and the siphoning off of 120 to 220 litres of allantoic fluid. The amnion was normal. Dystocia, due to uterine inertia, occurred in all eight cases, one hydrocephalic fetus needing fetotomy. All fetuses were alive at delivery although four were tera...
Pieńkowska-Schelling A, Becker D, Bracher V, Pineroli B, Schelling C.Numerical and structural aberrations of chromosomes may cause malformations, embryonal losses and reduced or missing fertility. In male horses the fertility is rather well controlled through their semen evaluation. For mares there are no mandatory regulations which specify their use in a breeding programme. Therefore, mares with chromosomal aberrations, which exclude reproduction success may be chosen for breeding. The present case describes a horse, offically registered as a female, which was presented for a breeding exam. On this occasion, small and inactive ovaries were diagnosed. Although ...
Schuler G.The pituitary gonadotrophins follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play a prominent role in the control of gonadal functions. Therefore, their use in the treatment of fertility disorders (e. g. anovulatory anestrus) as well as in biotechnology (e. g. superovulation, hormone programs for cycle synchronization) is of substantial interest. Preparations of FSH or LH are relatively expensive due to the laborious extraction from pituitary tissue and are therefore reserved for special indications. In primates and equids, the chorionic epithelium expresses an LH-like molecule...
Vissani MA, Zabal O, Tordoya MS, Parreño V, Thiry E, Barrandeguy M.Equid alphaherpesvirus 3 (EHV3) is the etiological agent of equine coital exanthema (ECE), which is a venereal, highly contagious disease, characterized by the formation of papules, vesicles, pustules and ulcers on the external genitalia of mares and stallions. EHV3 remains in a latent state after a successful infection and there are latently infected animals in which the virus is reactivated and generally re-excreted subclinically. There are no available vaccines for this condition and prevention is based on the clinical examination of mares prior to mating, which allows to segregate those sh...
Bazzano M, Giannetto C, Fazio F, Marafioti S, Giudice E, Piccione G.Hemostasis is a physiological process that prevents excessive blood loss and represents a protective mechanism at the time of delivery. Peripartum hemorrhage is a recurring hazardous condition to mare's health; therefore, we aimed to study mares' hemostatic profile to investigate whether physiological adjustments occur during late pregnancy and early postpartum. Fifteen pregnant mares have been monitored from the 34th week of pregnancy until the third week after foaling. Fifteen nonpregnant mares were used as control group. Jugular blood samples were analyzed for platelet count (Plt), prothrom...
Ferreira-Dias G, Mateus L, Costa AS, Solá S, Ramalho RM, Castro RE, Rodrigues CM.Soon after ovulation, the newly formed corpus luteum (CL) starts secreting progesterone (P(4)), necessary for implantation. The CL, an ovarian transient endocrine organ, undergoes growth and regression throughout its life span. The objective of this study was to evaluate if caspase-3 mediates cell death in the equine cyclic luteal structures and relate it to luteal endocrine function. Blood and luteal tissue were collected during the breeding season after slaughter from 38 randomly assigned cycling mares. Luteal tissues were classified as corpora haemorrhagica (CH; n = 7); mid luteal phase cor...
King SS, Jones KL, Mullenix BA, Heath DT.Dopamine (DA) blockade during anestrus or early spring transition can facilitate ovarian recrudescence and advance the timing of the first ovulation of the season. Some laboratories have reported variable results using DA antagonists to stimulate follicular growth during the mid-portion of the anestrual period. Differences in DA antagonist efficacy may be due to the FSH secretory status of the anestrous mare and the presence or absence of functional ovarian FSH receptors. We hypothesize that direct ovarian dopaminergic input can affect follicular growth through regulation of FSH receptor (FSHr...
Mouncey R, Arango-Sabogal JC, de Mestre A, Verheyen K.The study aimed to (1) describe the use of reproductive therapeutics; (2) estimate the incidence of disease and injury; and (3) describe non-reproductive medications administered during pregnancy in Thoroughbred broodmares. A prospective birth cohort was established on seven farms across the UK and Ireland. Details of dams' signalment, breeding history, reproductive management during the breeding season(s) and veterinary-attended episodes of illness or injury and medication usage during gestation were retrieved retrospectively for 275 pregnancies in 235 mares over two breeding seasons. Results...
Lyle SK.Placentitis is reported to be the cause of 9.8-33.5% of abortions, stillbirths and perinatal losses in horses. Bacterial infections are responsible for 53% of placentitis cases with Streptococcus equi ssp. zooepidemicus being isolated in 28% of these cases. Clinically, mares may have a vaginal discharge, show udder development, lactate prenatally and deliver a premature or dead foal. Major aspects of the pathogenesis of infectious preterm delivery that may require more effective therapeutic targeting are myometrial contraction, immunological aspects of preterm delivery, and the effects of proi...
Raeside JI, Christie HL, Waelchli RO, Betteridge KJ.The embryo proper in early equine pregnancy has recently been shown to have a remarkable capacity for metabolism of oestrogens. High concentrations of oestrogens in yolk-sac fluid could provide substrate for local metabolism in tissues of the embryo proper and this activity could have significance for early development. Due to the high level of oestrogen metabolism in the embryo proper we examined the possibility that it could also biosynthesise oestrogens. Conceptuses were collected in the fourth week of pregnancy (n=23) and the embryo was separated from extraembryonic tissues for incubation ...
Vanderwall DK, Hyde KJ, Woods GL.To determine whether performance of transvaginal ultrasound-guided follicle aspiration (TVUFA) repeatedly in mares adversely affects their fertility. Methods: Historical prospective study. Methods: 23 mares that had never undergone TVUFA and 59 mares that had undergone TVUFA on 1 to 11 occasions. Methods: Mares were classified into 4 groups according to the number of TVUFA procedures previously performed on the ovary in which ovulation occurred at the time of insemination as follows: group 1, 0 TVUFAs (control group, n = 23 mares); group 2, 1 or 2 TVUFAs (40 mare-cycles); group 3, 3 or 4 TVUFA...
Almeida BFM, Amatti LZ, de Souza GG, Garcia LV, Montechiesi DF, Ignácio FS, de Oliveira PL, Costa LR, Floriano BP, Bosculo MRM, Joaquim JGF, Rubio CP.With the purpose of assessing the effects of uterine ozone therapy and anticoagulant sampling on oxidative stress (OS) parameters in mares, ten mares underwent three consecutive days of uterine ozone therapy by flushing the uterus with ozonated lactated Ringer's solution followed by insufflation with ozone‑oxygen gas. Serum samples were obtained at baseline and days 3, 6, 10 and 17 to determine the effect of ozone therapy on OS markers. Plasma obtained with anticoagulants citrate, ethylenediaminetetraacetic acid (EDTA) and heparin were at baseline and 6 days following therapy to determine t...
Martin B, Silberzahn P.A significant decrease of CBG binding capacity in plasma of the mare throughout pregnancy was demonstrated using equilibrium dialysis and gel equilibration methods. As indicated with immunoelectrophoresis experiments, the pregnancy related fall of CBG binding capacity was linked to an actual decrease in blood CBG concentration. This result contrasts sharply with data on most other mammalian species, with the exception of the gestating rhesus monkey.
Ginther OJ.The mechanism for selection of the future dominant or ovulatory follicle in mares involves a relatively abrupt separation in growth rates between the future dominant follicle and several subordinate follicles and is termed diameter deviation. The event is used to illustrate that a coordinated complex of many follicular, hormonal, and biochemical factors interact and interbalance during a single physiological mechanism. For example, a positive effect of follicle stimulating hormone (FSH) on development of all follicles during the growing phase can later involve a positive effect of luteinizing ...
Lucas Z, Raeside JI, Betteridge KJ.Field observations of 400 totally unmanaged feral horses on Sable Island, Nova Scotia, were complemented by oestrogen determinations in faecal samples from 154 identified females over a 4-year period (454 mare-years). Of mares that were sampled throughout the year and subsequently produced foals, 92.1% exhibited elevated faecal oestrogens between 15 October and 30 March. The results confirm that faecal oestrogens are a useful indicator of pregnancy after approximately 120 days gestation. Distribution of foaling resembled that seen in other feral populations, with 95% of births occurring from A...
Bugno M, Słota E.A 5-year-old infertile Hutsul mare was subjected to cytogenetic analysis. Fluorescence in situ hybridisation (FISH) using the equine Xp and Xq chromosome painting probes was carried out on chromosome preparations obtained after blood lymphocyte culture. These probes were generated by chromosome microdissection and a large number of spreads was analysed (525). The karyotype formula of the analysed mare was 64,XX/65,XX+Xp with the ratio of the two lines being 99.4 and 0.6, respectively. The goal of the study was to apply chromosome microdissection and the FISH technique for cytogenetic diagnosti...
Lindsey AC, Morris LH, Allen WR, Schenk JL, Squires EL, Bruemmer JE.The objectives of this study were 1) to compare pregnancy rates resulting from 2 methods of insemination using low sperm numbers and 2) to compare pregnancy rates resulting from hysteroscopic insemination of 5 x 106 nonsorted and 5 x 106 spermatozoa sorted for X- and Y-chromosome-bearing populations (flow sorted). Semen was collected with an artificial vagina from 2 stallions of known acceptable fertility. Oestrus was synchronised (June to July) in 40 mares, age 3-10 years, by administering 10 ml altrenogest orally for 10 consecutive days, followed by 250 microg cloprostenol i.m. on Day 11. Al...
Aoki T, Kimura Y, Oya A, Chiba A, Ishii M, Nambo Y.Heavy draft mares potentially have a higher risk of suffering from postpartum fever (PF) than light breed mares. The purpose of this study was to compare hematological and biochemical features between clinically healthy mares (n=40) and PF-affected mares (n=16). Mares were classified as having PF when their rectal temperature rose to >38.5°C within 96 hr of foaling. The numbers of leukocytes, lymphocytes, and neutrophils and the serum magnesium level were significantly lower in PF-affected mares. The serum SAA and NEFA levels were significantly higher in PF-affected mares. Strong inflammation...
Pinto CR, Paccamonti DL, Eilts BE, Short CR, Godke RA.Recent studies suggest that nitric oxide (NO) may have a role in regulating ovarian physiology. To investigate the role of NO during ovulation in mares, inhibitors of the nitric oxide synthase (NOS) were administered to estrous mares. Forty cycling mares (20 horses and 20 pony mares) were allotted to one of the three treatment groups. Once a follicle was at least 27 mm in diameter, but smaller than 35 mm, mares were given one of the following treatments: saline solution 0.9% (n = 20, w/v, i.v., every 12 h), Nomega-nitro-L-arginine methyl ester hydrochloride (L-NAME; n = 10, 148 micromol/kg, i....
Aurich C, Daels PF, Ball BA, Aurich JE.The aim of the present study was to investigate the role of ovarian steroids in the opioid regulation of LH and prolactin release in mares. Effects of the opioid antagonist naloxone on LH and prolactin secretion were determined in ovariectomized pony mares. The animals were pretreated with either progesterone (500 micrograms kg-1) or oestradiol benzoate (10 micrograms kg-1) for 8 days and subsequently with a combination of progesterone and oestradiol for an additional 8 days. Naloxone administration (0.5 mg kg-1 i.v.) resulted in a significant release of LH as well as prolactin in mares after ...
Venner M, Markus RG, Strutzberg-Minder K, Nogai K, Beyerbach M, Klug E.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...
Wespi B, Sieme H, Wedekind C, Burger D.Horses (Equus caballus) belong to the group of seasonally polyestrous mammals. Estrous cycles typically start with increasing daylight length after winter, but mares can differ greatly in the timing of onset of regular estrus cycles. Here, we test whether spatial proximity to a stallion also plays a role. Twenty-two anestrous mares were either exposed to one of two stallions (without direct physical contact) or not exposed (controls) under experimental conditions during two consecutive springs (February to April). Ovarian activity was monitored via transrectal ultrasound and stallion's direct ...
Waller CA, Thompson DL, Cartmill JA, Storer WA, Huff NK.Previous results from our laboratory indicated that a majority of mares with high body condition scores (BCS) displayed estrous cycles or had considerable follicular activity during the winter. Among these high BCS mares, about 35% of them exhibited a persistent hyperleptinemia and hyperinsulinemia. The current experiment was designed to compare the reproductive characteristics of high BCS mares with hyperleptinemia to those with normal (low) plasma concentrations of leptin during the winter and the first estrous cycle (or the first full cycle encountered for those already cycling). Light hors...
Marino E, Threlfall WR, Schwarze RA.The ECF lateral flow assay test is marketed to detect non-pregnancy in mares. The objectives of the present study were to determine the accuracy of the ECF test, the accuracy of the electronic reader accompanying the ECF test, and agreement between two human readers and the electronic reader. Serum samples were collected from anestrus, cycling but not inseminated, and inseminated mares, and were evaluated with the ECF test (EDP Biotech Company, Knoxville, TN, USA) at The Ohio State University and at the EDP Biotech Laboratory. Specificity ranged from 0.07 to 0.16, the negative predictive value...
IJzer J, van den Ingh TS.A 15-year-old Dutch Warmblood mare presented with respiratory distress and anorexia. Clinical examination revealed liquothorax and an abdominal mass. At necropsy, an infiltrating tumour was found in the visceral trunk, continuing through the diaphragm into the mediastinum. Histopathology, immunohistochemistry and electronmicroscopy showed empty channels lined by atypical endothelial cells, and neoplastic cells in a disorganized pattern, consistent with the diagnosis of a lymphangiosarcoma.
Pazinato FM, Curcio BDR, Fernandes CG, Santos CA, Feijó LS, Varela AS, Nogueira CEW.The objective of this study was to assess the placental vasculature and microcotyledons in pregnant mares with chronic laminitis. Twenty-six pregnant mares were enrolled in the study, 13 had chronic laminitis (Laminitis Group) and 13 were healthy mares (Healthy Group). Arterial systolic pressure and heart rate were measured in the last 30 days of gestation. After foaling, the fetal membranes were grossly evaluated and samples were harvested for histopathologic examination. All mares had digitalized images taken from chorioallantois for histomorphometry analyses (software-NIH ImageJ). Images we...
Davies Morel MC, Lawlor O, Nash DM.Endometritis is an important cause of sub-fertility in mares. The critical indicator of reproductive success and financial return for commercial studs is live foaling rate. Endometrial bacteriology and/or cytology are used to diagnose endometritis and thus identify mares at risk of early embryonic death. However, mares with endometritis may conceive but then abort in late gestation. The aims of this study were to establish, as part of a standard breeding examination (1) whether a threshold percentage of uterine polymorphonuclear neutrophils (PMNs) exists above which a significant reduction in ...
Watson ED, Buckingham J, Björkstén T, Nikolakopoulos E.The presence of oxytocin in the mare uterus was determined by radioimmunoassay of tissue extracts and uterine lavage fluid, and by immunohistochemistry. Samples were obtained from mares during the oestrous cycle and on day 14 of pregnancy. Immunoreactive oxytocin was detected in extracts of endometrium and myometrium, and in uterine lavage fluid. In tissue sections, the luminal epithelium, the epithelium of the superficial, but not deep, glands, blood vessel walls and myometrium all stained positively for oxytocin, whereas only the luminal epithelium and epithelium of the superficial glands st...
Mari G, Rizzato G, Merlo B, Iacono E, Bucci D, Seren E, Tamanini C, Galeati G, Spinaci M.Little information is available on the quality of stallion spermatozoa after sex sorting. The objectives of the present study were to assess the quality of sex-sorted stallion spermatozoa and determine its fertilizing ability after hysteroscopic low dose insemination. Ejaculates from four stallions were collected and sorted by a MoFlo SX flow cytometer/sperm sorter. Before and after sorting, spermatozoa were evaluated for motility by Computer Assisted Sperm Analysis, viability (SYBR 14-propidium iodide), mitochondrial function (JC-1) and acrosomal status (fluorescein isothiocyanate Pisum sativ...
Ellero N, Lanci A, Baldassarro VA, Alastra G, Mariella J, Cescatti M, Giardino L, Castagnetti C.The importance of trophic factors, such as nerve growth factor (NGF), vascular endothelial growth factor (VEGF), and brain-derived neurotrophic factor (BDNF) during the perinatal period, is now emerging. Through their functional activities of neurogenesis and angiogenesis, they play a key role in the final maturation of the nervous and vascular systems. The present study aims to: (i) evaluate the NGF and VEGF levels obtained at parturition from the mare, foal and umbilical cord vein plasma, as well as in amniotic fluid; (ii) evaluate NGF and VEGF content in the plasma of healthy foals during t...
