Reproduction in horses encompasses the biological processes and mechanisms involved in the breeding and development of equine offspring. This includes the study of reproductive anatomy, physiology, and endocrinology in both mares and stallions. Key areas of interest include the estrous cycle, ovulation, conception, gestation, and parturition. Researchers also examine factors influencing fertility, reproductive technologies such as artificial insemination and embryo transfer, and management practices that impact reproductive success. This page compiles peer-reviewed research studies and scholarly articles that explore the physiological, genetic, and environmental aspects of equine reproduction.
López Alvarez ML, Bustos Obregón E.The occurrence of phagocytosis of spermatozoa in the epididymis is a controversial issue in male reproductive biology. In this paper we documented, by scanning and electron microscopy, the presence of spermatophages in the lumen of the proximal region of stallion epididymis. Sperm phagocytosis involving the principal cells that line the cauda epididymidis region was also observed. The possible meaning of this process in the removal of damaged, aged or surplus spermatozoa is discussed. These observations were made in samples obtained from random cases, during the course of research work carried...
Kask K, Malmgren L, Odensvik K.Hormonal, chemical, and mechanical stimuli can activate the arachidonic acid cascade and result in formation of prostaglandins and related substances. These compounds can have a profound role in the initiation of the inflammatory process (Higgins & Lees 1984). Prostaglandin (PG) F2α is the key hormone in reproductive physiology with well-known effects on reproductive performance e.g. luteolysis and abortion. An activation of the arachidonic acid cascade, caused by mechanical manipulation during an embryo transfer procedure, might be one explanation for early embryonic loss.
Grandi D.An ultrastructural and immunohistochemical analysis was performed on the epiphysis of two species of mammals: mink and horse. These animals present a reproductive cycle that varies along the year according to the light exposition. The aim of the study was to define possible structural changes connected with the gonadal activity. Structural aspects in common emerged such as those in concern with the epiphysis cells, their immunocytochemical characteristics (NSE and Synaptophysin positivity of pinealocytes, as well as CFAP positivity of further cells), and those in concern with the general ultra...
Eisenhauer KM, Roser JF.A stallion testicular cell incubation system was developed and used to investigate the regulation of steroidogenesis in stallion testes. Cells isolated from testes of 2- to 4-year-old stallions (n = 6) were cultured for 12 hours in a defined medium with and without varying doses of lipoprotein, equine luteinizing hormone (eLH), human chorionic gonadotropin (hCG), equine follicle-stimulating hormone (eFSH), and/or equine prolactin (ePRL). Estrogen conjugate (EC), testosterone (T), and estradiol-17 beta (E2) production were determined by RIA. Increasing doses of lipoprotein significantly (P <...
Lennard SN, Stewart F, Allen WR.Placentation in equids involves two types of trophoblast: a minor invasive component, the chorionic girdle, that gives rise to transient endocrine structures known as endometrial cups, and a major non-invasive component, the allantochorion, that forms the diffuse, microcotyledonary placenta. Growth factors are likely to be important in controlling these complex events at implantation and this study describes the use of in situ hybridization and northern blotting techniques to monitor expression of insulin-like growth factor II (IGF-II) in the fetus and placenta of the horse (Equus caballus), u...
Yamada M, Gentry PA.The coagulation factors VII and X and fibrinogen were detected in equine ovarian follicular fluid. The amounts of fibrinogen and factor X were approximately 40 percent of that found in normal equine plasma while the level of factor VII was lower, at approximately 14 percent. The addition of human recombinant tissue factor caused fibrin formation in the follicular fluid. The thrombin generating activity appears to be confined to the tissue factor pathway since no activity associated with factors VIII:C, IX or IX was detected. Fibrinolytic activity, at higher levels than that found in plasma, wa...
Gånheim A, Gånheim A, Jöchle W.In a blinded trial, the effectiveness and safety of 2.2 mg of the GnRH analog deslorelin acetate, administered in a short-term implant (STI) to normally cycling mares in estrus with a dominant ovarian follicle of 30 mm in diameter or larger, were evaluated, using a placebo implant as a negative control. A total of 39 mares received treatments at admittance with pre-randomized implants containing either 2.2 mg or 0 mg deslorelin. Mares were teased daily and examined rectally with ultrasound at 24 h intervals to determine time to ovulation and duration of estrus. The number of breedings and the ...
Boosinger TR, Brendemuehl JP, Bransby DL, Wright JC, Kemppainen RJ, Kee DD.Newborn foals of mares grazing on Acremonium coenophialum-infected fescue pasture throughout gestation or from gestation day 300 to parturition had increased gestation duration and decreased serum triiodothyronine concentration. Pregnant mares were allotted to 4 treatments: grazing continuously on endophyte-free (E-) fescue, grazing continuously on endophyte-infected (E+) fescue, grazing on E+ fescue from gestation day 300 to parturition, and grazing on E+ fescue from conception to gestation day 300. Morphometric studies indicated that foals born to mares exposed to endophyte late in gestation...
Madsen M, Christensen P.Semen samples were collected from 21 Danish Warmblood stallions by the Colorado artificial vagina (Colorado AV, 14 samples) or by the Missouri artificial vagina (Missouri AV, 7 samples). The semen was examined bacteriologically by direct plating (DP) on blood agar plates, and by plating of semen swabs stored in Stuart's transport media (TM) at 4 degrees C for 1-4 days. No significant differences were observed between results obtained by DP and cultures of identical TM samples. Of the 21 samples examined, only 1 TM (4.8%) and 2 DP samples (9.5%) were sterile, while the rest yielded a predominan...
Hochi S, Fujimoto T, Oguri N.Viability following vitrification of equine blastocysts with different sizes was investigated in vitro. Twenty-four blastocysts were classified into three groups according to their diameters ( 300 microns; n = 8 each). The solution used for vitrification was defined as EFS and contained 40% ethylene glycol, 18% Ficoll and 0.3 M sucrose in modified-phosphate-buffered saline (m-PBS). During pretreatment with 20% ethylene glycol in m-PBS for 20 min, the larger blastocysts responded to the osmotic pressure caused by 20% ethylene glycol more slowly than the smaller blastocysts. Single blastocysts w...
Meyers SA, Overstreet JW, Liu IK, Drobnis EZ.Mammalian sperm that have completed capacitation are capable of undergoing the acrosome reaction in response to a number of biological and chemical stimuli. In the present report, we have investigated the ability of progesterone to stimulate acrosome reactions of stallion sperm capacitated in vitro. Motile sperm were selected by a two-layer Percoll gradient centrifugation and were incubated in TALP medium modified by the 1:1 (v/v) addition of TEST-yolk medium for 5 hours at 39 degrees C, under 5% CO2 in humidified air. Sperm incubated in vitro in TALP-TEST medium had a higher percentage of acr...
Sailer BL, Jost LK, Evenson DP.Sperm from four mammalian species were analyzed by the sperm chromatin structure assay (SCSA) and the terminal deoxynucleotidyl transferase assay (TdTA) using flow cytometry. The SCSA quantitates the susceptibility of sperm nuclear DNA to in situ acid denaturation, while the TdTA quantitates the presence of endogenous DNA strand breaks in sperm nuclear chromatin. Correlations were seen between the percentage of sperm cells showing susceptibility to in situ acid denaturation and the percentage of cells showing the presence of DNA strand breaks for humans (r = 0.56, P = 0.004), rams (r = 0.84, P...
Hassel DM, Ragle CA.The research study details the diagnosis and treatment of a uterine tear in a 12-year-old Quarter Horse mare, which had complications during labor. The mare, displaying signs of prolonged labor, […]
Perkins NR, Frazer GS.This article briefly reviews the clinical management of emergency conditions likely to be encountered by veterinarians responsible for the reproductive health of mares. The article discusses rectal tears, breeding injuries, uterine torsion, placental hydrops, and prepubic tendon rupture. A major component discusses a recommended approach to dystocias, and the management of such complications as uterine rupture and prolapse and postpartum hemorrhage. Management of retained fetal membranes and septic metritis is addressed.
Perkins NR, Frazer GS.Topics addressed in this article include complications of castration, scrotal and inguinal hernias, torsion of the spermatic cord, traumatic injuries to the external genitalia, and posthumous collection of spermatozoa. A concise overview of the clinical management of emergency cases is provided.
Davis TA, Nguyen HV, Garcia-Bravo R, Fiorotto ML, Jackson EM, Reeds PJ.To determine whether the amino acid composition of milk changes during lactation, we compared the amino acid pattern (concentration of each individual amino acid relative to the total amino acid concentration) of colostrum with that of mature milk in six mammalian species. In the human, horse, pig and cow, the pattern of amino acids changed between colostrum and mature milk: glutamate, proline, methionine, isoleucine and lysine increased; cystine, glycine, serine, threonine and alanine decreased. In these four species, the total amino acid concentration also decreased 75% between colostrum and...
Stammers JP, Hull D, Silver M, Fowden AL, Ousey J, Rossdale PD.An in vitro incubation technique was used to examine release of lipids from the equine placenta. Placental tissue was obtained at term (n = 5, term = 320-365 days) and earlier in gestation (n = 8, mean = 266 days). Term placentae were incubated at two temperatures, 4 degrees C (control) and 37 degrees C for 2 h. Pre-term placentae were incubated at 37 degrees C with two different concentrations of fatty acid in the medium. Tissues and media were analysed for their lipid concentrations. Term and pre-term placentae released free fatty acid (FFA) and phospholipid into the incubation medium during...
Braun J.Although foals born after embryo transfer are eligible for registration in the majority of horse breeds, application of embryo transfer is still rare. This is mainly due to the lack of a possibility for superovulation. Uterine stage embryos can be recovered by a non-surgical flushing technique. Transfer can be accomplished by non-surgical as well as surgical methods. In contrast to the situation in cattle, most related technologies are scarcely available. Methods of cryopreservation as well as bisection of embryos are hampered by the fact that suitable embryos (morula) can be collected from th...
de Brabander HF, van Hende J, Batjoens P, Hendriks L, Raus J, Smets F, Pottie G, van Ginkel L, Stephany RW.When residues of nortestosterone (NT) were found in the urine of cattle, racehorses or bodybuilders, exogenic administration was thought to be proven. In previous literature, no records were found of the endogenic presence of this molecule. In the horse-racing world, Houghton and Courthot found that NT is normally present in the urine of the stallion. Belgian and Dutch researchers found that NT is also present in the urine and edible parts of the intact boar. Vandenbroeck et al. (1991) suggested the endogenous presence of NT (in the beta form) in the pregnant cow. Meyer (1992) reported the pre...
Aurich C, Sieme H, Hoppe H, Schlote S.To investigate the involvement of endogenous opioids in the regulation of gonadotrophin release in male horses, effects of the opioid antagonist naloxone (0.5 mg kg-1 i.v.) on plasma LH and testosterone concentrations and the possible influence of season and of gonadal steroids were investigated. To determine quantitative as well as qualitative changes in gonadotrophin release, LH concentrations were measured by radioimmunoassay and by an in vitro bioassay. Experiments were performed in May, August and December. In stallions, basal LH secretion in May and August was significantly higher than i...
Younis AI, Sehgal PK, Biggers JD.A single s.c. injection of 1000 IU of pregnant mare's serum gonadotrophin (PMSG) stimulates the growth of multiple antral follicles in cynomolgus monkeys (Macaca fascicularis). The number of cumulus-enclosed oocytes (CEO) from six non-stimulated controls was 36 (mean = 6). In contrast, a total of 95 CEO (mean = 31.7) were recovered from three animals stimulated and ovariectomized 3 days later, while 385 CEO (mean = 128.3) were obtained from three animals stimulated and ovariectomized 4 days later. A comparison of the effects of highly purified human follicle-stimulating hormone (FSH), human lu...
Brinsko SP, Ball BA, Miller PG, Thomas PG, Ellington JE.This study was designed to investigate the development of day 2 embryos obtained from young and aged mares, co-cultured with oviductal epithelial cells obtained from mares in each age group in a 2 x 2 crossover design. Young, fertile mares (n = 19; 2-7 years of age) and aged, subfertile, mares (n = 16; 17-24 years of age) were used as embryo and oviductal epithelial cell donors. Embryos (n = 37) were collected from the oviducts 2 days after ovulation and were paired (embryos obtained from young mares with embryos obtained from aged mares) so that eight pairs were co-cultured with young mare ov...
Redina OE, Amstislavsky SYa , Maksimovsky LF.This study examined the developmental capacity of oocytes in DD mice after they had been injected with pregnant mares' serum gonadotrophin at different stages of the oestrous cycle. The superovulation of mature DD mice at pro-oestrus, oestrus and metoestrus resulted in a large yield of viable embryos. The proportion of abnormal embryos was highest after injection of pregnant mares' serum gonadotrophin at dioestrus. The pool of viable oocytes was most synchronized with normal development after the hormone was injected at oestrus. The results demonstrate that oocytes of different morphology coul...
Santschi EM, Slone DE.Infertility was associated with a uterine mass in 2 Thoroughbred mares. Both mares had produced live foals, but had been barren for 2 years, despite repeated breedings. Each mass was removed through a right ventral paramedian incision. Histologic examination of the masses revealed a leiomyoma and an ovarian abscess. In 1 mare, approximately 30% of 1 uterine horn was removed because of tumor attachment; in the other mare, approximately 50% of 1 uterine horn was removed because of adhesions to the ovarian abscess. Pregnancy information was available for both mares for the 3 years after surgery; ...
Choi YH, Okada Y, Hochi S, Braun J, Sato K, Oguri N.Frozen-thawed ejaculated stallion spermatozoa were preincubated for 3 h in BO medium containing 5 mM caffeine and then treated with 0.1 micro M calcium ionophore A23187 for 60 sec. Aliquots of the sperm suspension (final concentration 1-2 x 10(7)/ml) were added to the oocytes which had been matured in vitro for 32 h. In Experiment 1, there were 3 groups of oocytes; cumulus intact, denuded zona-intact, and zona-free. Cumulus cells were removed with 0.5% hyaluronidase and the zona pellucida with 0.1% protease. The oocytes were fixed 20 h after insemination with acetic acid:ethanol (1:3) and stai...
Gobbetti A, Zerani M, Vannucci F, Marini R.To delineate endocrine mechanisms regulating equine luteal function and the possible functional differences between one month and three month corpora lutea of pregnancy (CL), the in vitro basal releases of prostaglandin F (PGF), prostaglandin E2 (PGE2), progesterone, and 17 beta-estradiol by one and three month CL of pregnant mares were evaluated. In addition, the in vitro effects of PGF2 alpha PGE2, progesterone and 17 beta-estradiol on synthesis of prostaglandins (PGs) and sex steroids were studied. PGF, PGE2, and 17 beta-estradiol secretion was higher in one month than in three month CL, wh...
Allen WR, Sanderson MW, Greenwood RE, Ellis DR, Crowhurst JS, Simpson DJ, Rossdale PD.A total of 18 experimental pony and 136 commercial maiden, barren and foaling Thoroughbred mares in seasonal or lactation-related anoestrus were injected subcutaneously with 1 or 2 slow-release D,L-lactide-glycolide co-polymer implants impregnated with 0.9 or 1.8 mg of the potent GnRH analogue, ICI 118 630, to give a daily release of, respectively, 30 or 60 micrograms analogue for 28 days; 32 of the Thoroughbred mares were also given a daily oral dose of 27.5 mg allyl trenbolone for 5 days after injection of the implant. Thirteen pony (76%) and 120 Thoroughbred (88%) mares ovulated 3-18 days a...
Sexton PE, Bristol FM.Bacteriology, histology, and scanning electron microscopy were used to evaluate uterine involution in 27 mares treated with daily injections of 150 mg of progesterone and 10 mg of estradiol-17 beta, commencing within 18 hours of parturition. These findings were compared with those for 24 untreated mares at postpartum day 10 or 11. The treatment resulted in significantly (P less than 0.05) greater uterine gland proliferation. Gland density was significantly (P less than 0.05) greater in mares treated for 6 to 10 days than in those treated 2 to 5 days. The proportion of ciliated cells to secreto...
Serafini R, Varner DD, Bissett W, Blanchard TL, Teague SR, Love CC.The effect of flash-freezing storage temperature on stallion sperm DNA has not been evaluated. Commonly, sperm are flash-frozen at various temperatures to preserve sperm DNA prior to analysis. It is unclear whether the temperature at which sperm are frozen and stored may affect the results of DNA assays. In this study, the neutral comet assay was used to evaluate the effect of flash-freezing storage temperature (freezer [-60 °C], dry ice [-78.5 °C], liquid nitrogen [-196 °C]) compared to fresh sperm DNA structure. In addition, intra- and inter-assay and intra- and inter-stallion variabil...
Neuhauser S, Palm F, Ambuehl F, Aurich C.In this study, effects of altrenogest treatment (0.088 mg/kg daily) given to mares during late gestation until parturition on the time and the process of foaling, neonatal adaptation and postnatal development were analysed. The number of animals was 6 in the treatment group and 7 in the control group. Gestational length tended to be shorter in mares given altrenogest. Birth weight of the foals and weight of the placenta did not differ between groups. The second stage of parturition was prolonged in the altrenogest-treated mares (p<0.05). Foals born to altrenogest-treated mares had a significan...
Pace MM, Sullivan JJ.Fertilization rate was highest in mares inseminated with frozen semen within 12 hr of ovulation. Foaling rate was improved (P less than 0-05) by increasing the number of motile spermatozoa inseminated from 40 X 10(6) to 80 X 10(6) but was not further improved by increasing the number to 160 X 10(6) or by increasing the frequency of insemination from once to twice daily. The fertilizing capacity of spermatozoa frozen in one of the hydrogen ion extenders studied was dependent upon relative osmotic pressure and method of freezing (ampoules or pellets). Adjusting glycerol concentration from 7% to ...
McCue PM, Hughes JP.Mares (n = 37) were treated on Days 2 and 4 post partum with a uterine lavage of 10 l of warm, sterile NaCl (0.9%) solution. Endometrial cytology and culture were performed on Day 7. Mares were bred on the first postpartum estrus by artificial insemination. Pregnancy rates were determined by ultrasound examination at Day 16 post ovulation. No differences were noted in degree of uterine inflammation or presence of uterine bacteria at Day 7 post partum between treated (n = 18) and control (n = 19) mares. Pregnancy rates at the first postpartum estrus for treated mares (55.5%) was not statistical...
Malinowski K, Johnson AL, Scanes CG.The ability of interrupted photoperiods to induce early estrus and ovulation was examined. Horse mares were exposed to long (16 h light) or short (10 h light), noninterrupted photoperiods, ambient light, or various interrupted photoperiod treatments from December 1 to April 15 (135 d). Follicular development was assessed by rectal palpation and estrous behavior was determined by teasing with a stallion. Serum concentrations of progesterone were used as an indicator of corpus luteum function. Differences among the light treatment groups were compared for the following behavioral and ovarian cha...
Saltiel A, Calderon A, Garcia N, Hurley DP.Ovarian activity, as measured by the presence of small (10-15 mm diam.), medium (15-30 mm) and large (greater than 30 mm) follicles, corpora haemorrhagica and corpora lutea (CL), was determined in a total of 3584 ovaries during 1 year using post-mortem specimens. There were significant correlations of the incidence of ovulated follicles (ovulations), large and medium follicles (P less than 0 . 001) and of the mean number of small follicles (P less than 0 . 05) per mare with respect to season. The yearly averages of ovulated, large and medium follicles were 30 . 1, 13 . 9 and 73 . 9%, respectiv...
Schnobrich MR, Turner RO, Belcher CN, Slack J.Transrectal ultrasound of the internal urogenital tract may be used to aid in the diagnosis of reproductive tract and urinary tract pathology in both stallions and geldings. Abnormalities of the accessory sex glands of geldings are uncommon, although prostatic masses have recently been described in adult geldings presenting with dysuria, stranguria, and/or hematuria. The purpose of this study was to describe the normal ultrasonographic features and sizes of the accessory sex glands, caudal ureters, and pelvic urethra in clinically normal geldings. Eleven healthy geldings with no history of uro...
Al-Jaru A, Goodwin W, Skidmore J, Raudsepp T, Khazanehdari K.Chromosome configurations and chiasma frequency during the metaphase I stage of spermatogenesis in the male horse are characterized in this work. The genome-wide frequency and distribution of chiasmata was detected as 49.45 ± 2.07 for 14 fertile stallions. All X and Y chromosomes shared a single chiasma at their pseudoautosomal region, while 1-4 chiasmata were observed in autosomal chromosomes. The chiasma frequency and distribution were further studied for 8 different bivalents identified by FISH in 5 fertile stallions. Genetic length was calculated from chiasmata data for the whole genome a...
Patterson AL, Squires EL, Hansen TR, Bouma GJ, Bruemmer JE.Maternal recognition of pregnancy is a physiological process that primarily describes endometrial responses to a conceptus. Recognition of a conceptus prevents the release of prostaglandin F(2α) , thereby ensuring survival of the corpus luteum and continued progesterone production. Exactly how this occurs in the mare is poorly understood. Because prostaglandin F(2α) is a pro-inflammatory hormone, we hypothesized that differential gene expression in the endometrium at the time of maternal recognition reflects an anti-inflammatory event leading to decreased prostaglandin F(2α) secretion. Mare...
Umair M, Beitsma M, de Ruijter-Villani M, Deelen C, Herrera C, Stout TAE, Claes A.The cryotolerance of equine blastocysts larger than 300 μm can be improved by aspirating blastocoele fluid prior to vitrification; however, it is not known whether blastocoele aspiration also enables successful slow-freezing. The aim of this study was therefore to determine whether slow-freezing of expanded equine embryos following blastocoele collapse was more or less damaging than vitrification. Grade 1 blastocysts recovered on day 7 or 8 after ovulation were measured (>300-550 μm, n = 14 and > 550 μm, n = 19) and blastocoele fluid was aspirated prior to slow-freezing in 10...
Bøgh IB, Baltsen M, Byskov AG, Greve T.In the cryptorchid stallion, spermatogenesis is arrested at various levels before the completion of meiosis. In men, infantile cryptorchidism is also often associated with oligo- and azoospermia during adulthood. An impairment of spermatogenesis might be reflected in the level of locally produced factors. Formerly, a meiosis-activating sterol (T-MAS) has been isolated in murine and bovine testes. This sterol possesses the potential to trigger resumption of meiosis in cultured mouse oocytes, indicating that it might play an important role in the regulation of the meiotic process in the female g...
Ginther OJ, Domingues RR, Dangudubiyyam SV, Araujo ER.Diameter deviation or follicle selection during a follicular wave begins with continuous growth rate of F1 (dominant or selected follicle; DF) and decreasing growth rate of F2 (largest subordinate). Intraovarian patterns based on presence or absence of the DF and CL are DF-CL, DF, CL, and devoid (neither DF nor CL). The DF and CL relationships in a pair of ovaries are ipsilateral (DF-CL pattern and devoid pattern) and contralateral (DF pattern and CL pattern). The effects of patterns and relationships on F1, F2, and FSH during deviation were determined in 21 mares. Diameters of F1 and F2 at ex...
Silberzahn P, Pouret EJ, Zwain I.Androgen (testosterone and androstenedione) and oestrogen (oestradiol -17 beta and oestrone) concentrations were measured by radio-immunoassay in the peripheral plasma of two geldings (five-years-old), three bilateral cryptorchids (two, two and a half, and five-years-old) and three normal intact stallions (four, five and five and a half-years-old) before and after a single injection of 10,000 iu human chorionic gonadotrophin (hCG). In the stallions, hCG administration resulted in an immediate sharp increase of conjugated oestrogens and a more gradual increase of unconjugated androgens. In the ...
Ferreira-Dias G, Costa AS, Mateus L, Korzekwa A, Redmer DA, Skarzynski DJ.Soon after ovulation, the corpus luteum (CL) starts secreting progesterone (P(4)), a hormone necessary for implantation. The aim of the study was to evaluate whether P(4) exerts an autocrine/paracrine action on luteal angiogenic activity and P(4), prostaglandin E(2) (PGE(2)) and NO production in the mare. Corpora hemorrhagica (CH) and mid-luteal phase CL (MCL) were cultured with (i) no hormone (Control); (ii) P(4); (iii) a P(4) precursor - pregnenolone; or (iv) a P(4) antagonist - onapristone [10(-4) M;10(-5) M; all steroids]. NO production decreased in MCL, with respect to CH, when treated wi...
Handler J, Hoffmann D, Weber F, Schams D, Aurich C.The aim of the present study was, to investigate the effects of oxytocin administration on Day 7 post-ovulation on progesterone secretion, pregnancy rate and embryonic growth in mares. Endogenous stimulation of oxytocin release was compared to the administration of native oxytocin or the long-acting oxytocin analogue carbetocin. At Day 7 after ovulation, mares had to undergo four treatments in a crossover design: (a) control, (b) oxytocin (10 IU i.v.), (c) carbetocin (280 microg i.m.) and (d) cervical dilation. On Day 13, all mares (8 of 8 mares) were pregnant on groups control, oxytocin and c...
Tonekaboni FR, Narenjisani R, Staji H, Ahmadi-Hamedani M.This investigation aimed to compare the cell-free fetal DNA (cffDNA) plasma present in three trimesters of pregnancy in Torkaman pregnant mare. Peripheral blood samples of 32 pregnant mares in three trimesters of pregnancy were collected in tubes containing ethylenediaminetetraacetic acid at three time points. Circulating cffDNA was extracted from 3 mL of maternal plasma. Using outer and inner primers, a conventional polymerase chain reaction was performed for the sex-determining region Y (SRY) gene present in the Y chromosome. Of the total 32 Torkaman pregnant mares, 24 were carrying male fe...
Stewart F, Maher JK.The number of genes encoding the common alpha-subunit and hormone-specific beta-subunits of the equine gonadotrophins (FSH, LH and CG) were investigated in the horse (Equus caballus), donkey (E. asinus) and 2 horse x donkey hybrids (the mule and hinny). The Southern technique, involving restriction enzyme digestion, blotting and DNA hybridization to 32P-labelled DNA probes was used to estimate the copy number for each gene and to assess the extent to which equids resemble primates, the only other animals that secrete a CG during pregnancy. These methods indicated that, in common with mammals, ...
Lefranc A-, Allen WR.The morphology and surface density of endometrial glands responsible for the nutrition of the placenta requires further study employing computer assisted morphometric analysis. Objective: To analyse changes in the morphology and surface density of endometrial glands situated adjacent to, and remote from, the conceptus during the first 30 days of gestation. Methods: Endometrial biopsies were recovered, under videoendoscopic control, from both nonpregnant and pregnant mares 12 days after ovulation, as well as from pregnant mares on Days 16, 20, 25 and 30 of gestation. One biopsy was taken at the...
Schulman ML, Marlow CH, Nurton JP.The data and an analysis of the statistical summaries from the 'Return of Mares' of the General Stud Book of The Jockey Club of Southern Africa from 1975-1999 are presented. The total number of mares covered per season ranged from 7393 (1992) to 5180 (1995). The total living produce in the period surveyed was 95 317 foals. The categories of data examined include: the total number of mares covered per season; the total numbers and percentage of their living produce; the total numbers and percentage dead produce, 'slips' and foals born dead, barren and 'no return' mares; and the total number of ...
Brinsko SP, Squires EL, Pickett BW, Nett TM.The objective of this study was to determine if prolonged pulsatile administration of homologous gonadotropin-releasing hormone (GnRH) at therapeutic or 5x therapeutic doses would cause down-regulation of the stallion's hypothalamic-pituitary-testicular axis. Fifteen stallions were randomly assigned to three treatment groups (n=5/group) and received a 0.5 ml subcutaneous dose of saline (group 1), 50 microg GnRH (group 2), or 250 microg GnRH (group 3) every 2 hours for 75 days. Weekly evaluations of follicle stimulating hormone, luteinizing hormone, and testosterone and monthly evaluations of d...
Michlik KM, Biazik AK, Henklewski RZ, Szmigielska MA, Nicpoń JM, Pasławska U.Quadricuspid aortic valve (QAV) and ventricular septal defect (VSD) are congenital heart defects and have been described in both human and veterinary medical literature. Methods: A 5-year-old half-bred bay stallion was referred for surgical castration. Cardiac murmurs were heard on the presurgical clinical examination and the cardiac examination revealed subcutaneous oedema, tachycardia with a precodrial thrill and a grade 5/6 pansystolic murmur, which was heard on auscultation of the right and left side of the chest. Examination of the B-mode echocardiograms revealed the presence of a QAV (on...
Liu IK, Cheung AT, Walsh EM, Miller ME, Lindenberg PM.The functional competence of peripheral blood and uterine-derived polymorphonuclear leukocytes (PMN) from 12 mares were analyzed for chemotactic responsiveness using a chemotactic chamber (filter) assay and for deformability by cell elastimetry analysis. Peripheral blood PMN obtained from control mares and from 8 mares experimentally inoculated via the uterus with 1 x 10(9) Streptococcus zooepidemicus had similar normal chemotactic responsiveness and were highly deformable before and at 12 hours after inoculation. Uterine PMN obtained 12 hours after uterine inoculation with S zooepidemicus fro...
LeBlanc MM, McLaurin BI, Boswell R.Postpartum, presuckle, colostrum samples were collected from 100 mares. Colostral specific gravities significantly correlated (r = 0.9) with colostral immunoglobulin (Ig)G concentrations. Foal serum IgG concentrations highly correlated (r = 0.82) with specific gravities of the colostrum each foal ingested. Eight of 48 foals (17%) had serum IgG concentrations less than 400 mg/dl. The dams of these 8 foals had colostral sp gr less than 1.06 and colostral IgG concentrations less than 3,000 mg/dl. Foals had serum IgG concentrations greater than 520 mg/dl 24 hours after parturition, when the colost...
Watson ED.Incubation of blood neutrophils with uterine flushings collected from ovariectomised mares treated with oestradiol, stimulated migration under agarose, whereas flushings from mares treated with progesterone or oily vehicle, inhibited migration. After intra-uterine infusion of bacteria, however, flushings from oestradiol-treated and vehicle-treated mares inhibited migration, whereas progesterone treatment stimulated migration. Migration of uterine-derived neutrophils under agarose was less than that of blood neutrophils and was not influenced by treatment with ovarian steroids. Uterine suscepti...
Raz T, Gray A, Hunter B, Card C.Superovulatory treatment may potentially increase the embryo recovery rate and the per-cycle pregnancy rate in normal or subfertile mares that are managed properly. However, some studies suggest a possible negative effect of superovulatory treatment on ovarian follicular maturation and embryo viability. Objectives of the present study were to investigate the early effects of eFSH treatment in reproductively normal mares in terms of: folliculogenesis, pregnancy rate, early embryonic development, reproductive tract parameters (tone and edema), and serum estradiol-17beta and progesterone concentr...
Hinrichs K.In vitro embryo production is not yet successful in the horse, largely due to low rates of fertilization in vitro. However, methods to produce embryos from isolated oocytes have been developed. Oocytes may be recovered from living mares by aspiration of the dominant preovulatory follicle by trans-abdominal puncture, and from both preovulatory and immature follicles by trans-vaginal ultrasound-guided puncture. Transfer of in vivo-matured oocytes to the oviducts of bred recipient mares has resulted in good pregnancy rates (75-85%). Little work has been done on transfer of horse oocytes matured i...
Casey PJ, Robertson KR, Liu IK, Espinoza SB, Drobnis EZ.Subfertility in stallions is common, and methodologies are needed to increase the fertility in these animals. In other species, removal of the dead sperm from semen increases the quality and fertility of semen. With horse semen we evaluated 48 combinations of column separation techniques using micro-spin chromatography columns. The greatest improvement in motility was observed with glass wool, whereas glass beads exhibited the greatest recovery of motile sperm. Although centrifugation time did not influence recovery rate or percent motility, a column length of 2 cm was superior for recovery of...
Domingues RR, Ginther OJ, Gomez-Leon V, Castro T, Wiltbank MC.In heifers and mares, multiple pulses of prostaglandin F2alpha (PGF) are generally associated with complete luteal regression. Although PGF pulses occur before and during luteolysis, little is known about the role of minor PGF pulses during preluteolysis on subsequent luteal and endometrial PGF production that may initiate luteolysis. Heifers (n = 7/group) and mares (n = 6/group) were treated with a single minor dose of PGF (3.0 and 0.5 mg, respectively) during mid-luteal phase (12 and 10 days postovulation respectively). After treatment, a transient decrease in progesterone (P4) con...
