Pregnancy in horses, or equine gestation, is a physiological process that involves the development of a foal within the mare over approximately 11 months. This period is characterized by distinct stages, including fertilization, embryonic development, and fetal growth. Throughout gestation, mares undergo various physiological and hormonal changes to support the developing fetus. Monitoring pregnancy in horses involves assessing fetal health and mare well-being through veterinary examinations and diagnostic tools such as ultrasound. This page compiles peer-reviewed research studies and scholarly articles that explore the physiological processes, management practices, and health considerations associated with equine pregnancy.
Bowen JM, Gaboury C, Bousquet D.A case of uterine torsion is described and its correction under general anaesthesia by a method described by Schaffer for the cow. The degree of torsion was 180 degrees and in a clockwise direction. After correction the foal was found to be alive and in anterior presentation and ventral position; it was born normally 84 days later.
Atkins DT, Harms PG, Sorensen AM, Fleeger JL.5alpha-pregnane-3,20-dione was isolated from pooled pregnant mare serum using Sephadex LH-20 column chromatography and identified by the use of radioimmunoassay, gas-liquid chromatography and gas-liquid chromatography-mass spectrometry analyses. 5beta-pregnane-3,20-dione was not cross-reactive with the radioimmunoassay system and was not detected by gas-liquid chromatography. Peripheral blood levels of progesterone and 5alphs-pregnane-3,20-dione were determined by radioimmunoassay in four Quarter Horse mares for the first 150 days of gestation. Progesterone and 5alpha-pregnane-3,20-dione decli...
Pal AK, Gupta T, Chatterjee A.A single consistent luteolytic dose of 10 IU PMSG given on day 5 of pregnancy caused complete resorption of foetuses and placentae associated with a polyfollicular ovarian state in rats. Concomitant treatment with progesterone or prolactin given concurrently with PMSG was found to overcome the antifertility efficacy of PMSG and maintained the endocrine balance favouring pregnancy maintenance. It was postulated that the PMSG-induced ovarian polyfolliculogenesis might be responsible for luteolysis of the corpus luteum gravidarum.
Samuel CA, Allen WR, Steven DH.In early pregnancy the equine placenta consists of a simple apposition of fetal and maternal epithelia, but it becomes more complex with the formation of microcotyledons between 75 and 100 days of gestation. Although the placental barrier maintains an epitheliochorial arrangement throughout the course of pregnancy, a thinning of the maternal epithelium and a progressive indentation of the chorionic epithelium by fetal capillaries shortens the length of the diffusion pathway and reduces the amount of placental tissue between fetal and maternal bloodstreams. These structural modifications may re...
Gleeson LJ, Sullivan ND, Studdert MJ.The inoculation of equine herpesvirus type 3 (EHV3) strain 65/61 into the amniotic cavity of a mare 6-7 months pregnant resulted in abortion 11 days later. Following abortion typical lesions of coital exanthema were not observed in the genital tract of the mare, nor was EHV3 isolated from her. Serological evidence, however, indicated that the mare was infected with EHV3 following inoculation. Grossly the foetal disease was characterised by placentitis, focal ulcerative dermatitis, focal necrosis of the lungs and a striking diptheritic gastritis. Histological findings were interstitial pneumoni...
Merkt H.The use and techniques of artificial insemination for horses in Germany over the last 30 years is described. Artificial insemination appears to produce pregnancy percentages equal to those from normal breeding methods and its continued availability under veterinary supervision is recommended in conditions where disease, disability or distance debar normal service.
Merkt H.The use and techniques of artificial insemination for horses in Germany over the last 30 years is described. Artificial insemination appears to produce pregnancy percentages equal to those from normal breeding methods and its continued availability under veterinary supervision is recommended in conditions where disease, disability or distance debar normal service.
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...
Nett TM, Pickett BW, Seidel GE, Voss JL.Jugular venous blood was collected from 16 mares at daily intervals throughout the estrous cycle. Twelve of these mares were bred to fertile stallions. Of the twelve, four were palpated daily throughout the estrous cycle, four were palpated daily during estrus and four were not palpated. The remaining four mares were not palpated or bred and blood samples were collected at 6-h intervals during estrus. Serum was harvested from all blood samples by centrifugation. The serum samples were analyzed for luteinizing hormone (LH) and/or progesterone by radioimmunoassay. Levels of LH in serum increased...
Tervit HR.Recent advances in reproductive physiology offer ways for exploiting superior, female cattle and for manipulating physiological events such as parturition. The techniques involved in these advances and their associated hazards are the subject of this review.
Nelson AM.Of 275 mares receiving prostaglandin F2alpha-Tham salt for its luteolytic effect upon the corpus luteum, 231 (84 per cent) exhibited signs of oestrus (range 73-95 per cent). Some mares not exhibiting overt oestrus may, nevertheless, ovulate and post-treatment rectal palpation of mares apparently failing to respond is suggested in these cases. Of 210 mares for which subsequent history was available. 104 (49.5 per cent) became pregnant from breeding at the post-treatment oestrus that immediately followed the induced regression of the corpus luteum (range 42.2-55.5 per cent). Fertility is compara...
Allen WR, Bowen JM, Frank CJ, Jeffcott LB, Rossdale PD.This short review article describes the various techniques currently available for artificial insemination in the horse. The collection and use of raw and extended semen is discussed together with the more recent developments in freezing semen. The expected conception rates with both fresh and frozen semen are quoted. The possible benefits in disease control and stud management are discussed, as well as the difficulties in controlling the use of A.I. from the Breed Registration Authorities point of view.
Allen WE.14 pregnant Welsh Mountain Pony mares were treated with progesterone in an effort to prevent pregnancy failure induced by administration of human chorionic gonadotropin (GCG). 13 of the 14 mares were treated with progesterone by injection or implant before the 38th day of pregnancy. HCG was given in 3 doses on alternate days at a dose rate of 2000 imc/day. The remaining mare was treated with HCG toward the end of the experiments to demonstrate the abortifacient property of HCG. 3 mares aborted and 1 of these was anovulatory thereafter. Further research is needed to determine the effective prog...
Douglas RH, Ginther OJ.Prostaglandins F were quantitated by radioimmunoassay in uterine venous plasma of anesthetized mares on day 7 of estrus, days 2, 6, 10, 14 or 18 of diestrus and days 10, 14 or 18 of pregnancy. The PGF concentration was greater (P less than .01) at day 14 of diestrus than at all other days studied. The concentrations at days 10 and 18 of diestrus and at days 10, 14 and 18 of pregnancy were greater (P less than .05) than at day 7 of estrus and days 2 and 6 of diestrus. PGF concentrations at days 10 and 14 were greater (P less than .01) for diestrous than for pregnant mares.
Nitschelm D, Van der Horst CJ.The hormonal pattern in the blood of eight mares was studied during the first 5 to 6 weeks of pregnancy; in two of the eight animals early embryonic death was established on D-28 and on D-40, respectively. Progesterone peaks were found in the blood around D-5, D-12 to D-10, and D-17 to D-18. It is suggested that the decrease of the progesterone concentrations in the blood during the intermediate periods is due to the action of oestrogens. During the period from D-18 to about D-34 the concentrations both of progesterone and of pregnenolone were low in the pregnant mares. Thereafter a small incr...
Kooistra LH, Ginther OJ.At day 24 of gestation, pregnant mares were allotted to 1 of 5 treatment groups (3 to 5 mares/group): group A--nontreated controls; group B--intraembryonic injection of 4 mg of colchicine on day 24; group C--removal of embryo on day 24; group D--subcutaneous injection of 1.25 mg of prostaglandin F2alpha (PGF2alpha) on day 32; and group E--removal of embryo on day 24 and subcutaneous injection of PGF2alpha on day 32. In all mares treated with colchicine (group B), the fetal bulge was absent within 2 days. The interval from injection of colchicine to onset of estrus was very short (mean, 4 days)...
Sharma OP.The concentrations of PGF-2alpha in the peripheral blood of five foaling mares were measured by radioimmunoassay. Low levels of PGF-2alpha were detected as early as 1 week before foaling in two of the mares. These levels increased steadily, reaching a peak (1-74 +/- 0-44 ng/ml) during fetal expulsion. A relatively high PGF-2alpha level was found in samples collected 60 min after foaling.
Vandeplassche M, Simoens P, Bouters R, De Vos N, Verschooten F.In 214 cases of severe dystocia in mares, of which 141 (66 per cent) were Draught horses, deviation of the head and neck, with or without torticollis, malformed head and limbs were found to be the cause of dystocia. No evidence of a genetic lethal factor was found and torticollis was often combined with scoliosis of the head and, frequently, with malformation of one or more limbs. This is considered evidence of a common aetiology and pathogenesis of the syndrome of malformation. The malformations were found to be associated with an increased incidence of caudal and, particularly, transverse pr...
Klewitz J, Krekeler N, Ortgies F, Heberling A, Linke C, Sieme H.To assess pregnancy and live foaling rates after reduction of twin pregnancy via transvaginal ultrasound-guided aspiration (TUA) in mares and evaluate effects of gestational period, localization of conceptuses, fluid aspiration volume, and combination of TUA with embryonic or fetal puncture on these outcomes. Methods: Clinical trial. Methods: 44 mares pregnant with twins (25 to 62 days of gestation). Methods: TUA was performed in all mares and combined with embryonic or fetal puncture in 13. Follow-up ultrasonographic examinations were performed by referring veterinarians. Effects of gestation...
Howey WP, Jochle W, Barnes WJ.Alfaprostal (K 11941), a novel prostaglandin F2 alpha analogue was clinically tested in 24 dioestrous mares, 40 anoestrous mares and 31 postpartum mares, all being given 2 or 3 mg intramuscularly. Blood samples were taken for the determination of plasma progesterone levels and the objective confirmation of luteolytic drug effects. Two hundred and thirty-six mares at the same location were used for comparisons of the rates of pregnancy, early embryonic loss and foaling. Alfaprostol was found to act as a potent luteolytic agent with good oestrus induction, follicular development and normal conce...
Ponthier J, de la Rebière G, Salciccia A, Deleuze S.In mares, endometrial cysts are associated with endometriosis and can cause maternal recognition failure or compromise and delay pregnancy diagnoses. Historical treatments were invasive and had adverse effects on the endometrium. Hysteroscopically guided laser therapy is easy and effective for endometrial cysts resection, with no deleterious effects for the endometrium. A 110 cm long and 1.0 cm wide endoscope is sterilely introduced in the uterus through the open cervix of an estrous mare after vulvar cleaning. The uterus is slowly infused with less than 1 L of physiologic solution and the las...
Morel MC, Newcombe JR, Reynolds N.The mare's reproductive system is rarely capable of sustaining multiple pregnancies to term. Multiple pregnancies largely derive from multiple ovulations, most commonly double ovulations, hence, double ovulations are of significant concern to breeders/veterinarians. Double ovulations may be synchronous or asynchronous. Asynchrony of up to 96 hours may result in two embryonic vesicles of very different sizes, which are challenging to detect at early ultrasonic pregnancy detection. This study aims to (1) document the incidence of synchronous and asynchronous double ovulation and (2) determine ...
Gastal GDA, Scarlet D, Melchert M, Ertl R, Aurich C.In embryos subjected to assisted reproductive techniques, epigenetic modifications may occur that can influence embryonic development and the establishment of pregnancy. In horses, the storage temperature during transport of fresh embryos before transfer is a major concern. The aim of this study was, therefore, to determine the effects of two storage temperatures (5 °C and 20 °C) on equine embryos, collected at day seven after ovulation and stored for 24 h, on: (i) morphological development; (ii) expression of candidate genes associated with embryo growth and development, maternal recognitio...
Paweska JT, Henton MM, van der Lugt JJ.Clinical, virological and serological responses were evaluated in 10 pregnant mares after different challenge exposures to the asinine-94 strain of equine arteritis virus (EAV). The outcome of maternal infection on the progeny was also investigated. Mares were inoculated intranasally (n = 4), intramuscularly (n = 2), intravenously (n = 1), or contract-exposed (n = 3). All inoculated mares developed pyrexia, 5 showed mild clinical signs related to EAV infection and 2 remained asymptomatic. Viraemia was detected in all the inoculated animals and shedding of virus from the respiratory tract occur...
Brockschmidt LD, Loch WE, Sikes JD.An experiment was conducted to test the effect of repeated transcervical (non-surgical) uterine flushing and a prostaglandin analogue (PG) on the estrous cycle of pony mares. Uteri in group A were trancervically flushed for embryos 7 to 9 days post ovulation. In addition, group B mares were given 5 ml of PG by intramuscular injection on the day of flushing. Group C served as controls and were not flushed or given PG but were allowed to cycle normally. All mares (except controls) were bred A.I. every other day during estrus. There was no effect on embryo recovery rate from repeated flushing or ...
Ousey JC, Rossdale PD, Cash RS, Worthy K.Multiparous pregnant mares, on two studfarms, were studied following natural challenge with equid herpesvirus-1 (EHV-1). They were divided into three groups according to serum complement fixation titres: Group A (N = 11) were not challenged and delivered normal foals; Group B (N = 13) were challenged but delivered normal foals; Group C (N = 23) were challenged and delivered infected foals which were stillborn or lived for less than 31 h. In Groups A and B mean (+/- s.d.) gestational age at delivery was 343 (+/- 8) and 339 (+/- 8) days respectively, whereas in Group C it was significantly (P le...
Leopold S, Samper JC, Curtis E, Buhr MM.Movement of Ca2+ into spermatozoa is a critically important event for capacitation and the acrosome reaction. In the present study, the nature of Ca2+ movement in fresh equine spermatozoa was established and the effects of oviductal cell conditioned medium (OCM) and cryopreservation on Ca2+ flux were investigated. The ability of fresh and cryopreserved stallion spermatozoa to regulate Ca2+ concentration over time was evaluated in Ca2+ -free PBS. Intracellular Ca2+ concentrations were higher in cryopreserved spermatozoa than in fresh spermatozoa. However, extracellular Ca2+ concentrations were ...
Darenius K.Fifteen mares which had each lost their pregnancies 2 to 8 times during the preceding 6 years were used in a study comprising 1 or 2 breeding seasons for each mare. During the research period all 15 mares conceived and 10 of the mares had normal pregnancies in the 1st experimental year. Five mares resorbed/aborted once or twice during the 1st year. This was followed by a pregnancy that terminated in a live foal. Histopathological examinations of uterine biopsies showed a wide range of histopathological conditions, from absence of changes excessive for the mare's age and parity to the most seve...
Kadivar A, Rashidzadeh H, Davoodian N, Nazari H, Dehghani Tafti R, Heidari Khoei H, Seidi Samani H, Modaresi J, Ahmadi E.Accurate diagnosis of foetal sex in pregnant mare is helpful for many breeders, both for private or commercial purposes. In this study, in order to pre-natal foetal sexing in equine, we used TaqMan duplex real-time PCR to detect the specific regions of SRY and TSPY genes on extracted cell-free foetal DNA from maternal blood. Peripheral blood samples from 50 pregnant Arabian mares with singleton foetuses were collected. Cell-free foetal DNA was extracted from maternal plasma, and duplex real-time PCR assays were performed with TaqMan probes and primers. Amplification of glyceraldehyde-3-phospha...
Gündüz MC, Kaşikçi G, Kaya HH.In this study, the effects of oxytocin and an analog of prostaglandin (cloprostenol) on the uterine involution and pregnancy rates were investigated. Mares received 3 ml of 0.9% NaCl in Group C (n=10), 30 IU/mare of oxytocin in Group O (n=10) and 250 microg/mare of cloprostenol in Group P (n=10) within 12h after parturition. The gravid uterine horn's cross-sectional diameter was measured by ultrasonography. The mean uterine diameters did not differ significantly between the treatment (O and P) and the control (C) groups (p>0.05). The difference between the postpartum ovulation periods (Grou...
Steven DH, Jeffcott LB, Mallon KA, Ricketts SW, Rossdale PD, Samuel CA.Post-partum placentae and uterine biopsy samples from mares after normal and abnormal foalings are described. After normal delivery there is little damage to fetal or maternal tissues. The villous epitheliochorial palcenta separates cleanly at the maternal-fetal interface and the afterbirth consists almost exclusively of fetal tissue. Uterine involution is well advanced by the 3rd and 4th days post partum and the changes are usually complete by the oestrus 7--10 days after parturition. Placental separation and involution of the uterus appear to proceed normally in malpresented foals and in oth...
Nitschelm D, Van der Horst CJ.The hormonal pattern in the blood of eight mares was studied during the first 5 to 6 weeks of pregnancy; in two of the eight animals early embryonic death was established on D-28 and on D-40, respectively. Progesterone peaks were found in the blood around D-5, D-12 to D-10, and D-17 to D-18. It is suggested that the decrease of the progesterone concentrations in the blood during the intermediate periods is due to the action of oestrogens. During the period from D-18 to about D-34 the concentrations both of progesterone and of pregnenolone were low in the pregnant mares. Thereafter a small incr...
Geisert RD.Establishment and maintenance of pregnancy in a number of mammalian species depends upon a tightly regulated interaction between the semiallogeneic conceptus and the maternal uterine endometrium.The term "Maternal Recognition of Pregnancy" is attributed to Roger V. Short's paper titled "Implantation and the Maternal Recognition of Pregnancy" which was published in proceedings from the 1969 Symposium on Foetal Autonomy.Professor Short's landmark paper stimulated increased interest in elucidating how the conceptus signals its presence to assure maintenance of the corpus luteum beyond the normal ...
McKinnon AO, Lacham-Kaplan O, Trounson AO.The use of intracytoplasmic sperm injection (ICSI) for in vitro fertilization of equine oocytes and the developmental potential of these oocytes after transfer to the Fallopian tubes of synchronized mares were examined. Oocytes were aspirated from mature follicles 39 h after injection of a GnRH analogue and transported 190 km at 39 degrees C. Semen from a fertile and an infertile stallion was frozen and prepared for injection. Successfully injected oocytes were transferred surgically into the ampulla of the Fallopian tube either: (i) 4-8 h after semen injection; or (ii) after 24-48 h culture b...
Pascoe DR, Stover SM.Twenty-one pregnant mares with single or twin conceptuses between 41 and 65 days of gestational age were allotted to 5 treatment groups. A ventral median celiotomy was performed in all mares. In group-1 mares (3 mares, single conceptus), the uterus and fetus were palpated for 5 minutes. In group-2 mares (3 mares, single conceptus, flunixin meglumine), 250 ml of sterile placental fluid was injected into the nongravid uterine horn. In group-3 mares (4 mares, unicornuate twin conceptuses), group-4 mares (3 mares, unicornuate twin conceptuses, flunixin meglumine), and group-5 mares (8 mares, bicor...
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...
Boakari YL, El-Sheikh Ali H, Dini P, Loux S, Fernandes CB, Scoggin K, Esteller-Vico A, Lawrence L, Ball B.High blood urea nitrogen (BUN) in cows and ewes has a negative effect on embryo development; however, no comparable studies have been published in mares. The aims of the present study were to evaluate the effects of high BUN on blastocoele fluid, systemic progesterone and Day 14 equine embryos. When a follicle with a mean (±s.e.m.) diameter of 25±3mm was detected, mares were administered urea (0.4g kg-1) with sweet feed and molasses (n=9) or sweet feed and molasses alone (control; n=10). Blood samples were collected every other day. Mares were subjected to AI and the day ovulation was detect...
Yamanouchi K, Hirasawa K, Hondo E, Hasegawa T, Ikeda A, Sugawara Y, Matsuyama S, Miyazawa K, Sawasaki T, Tojo H, Tachi C, Takahashi M.The expression of inhibin alpha-subunit mRNA in equine fetal gonads during pregnancy (Days 90 to 300) was examined by means of Northern blot analysis. In all samples examined, a single species of transcript was detected at the size of 1.5 kb. A digoxigenin-labeled antisense cRNA probe specific to equine inhibin alpha-subunit was synthesized and in situ hybridization analysis to locate the inhibin alpha-subunit mRNA positive cells was performed using frozen tissue sections of equine fetal ovary (day 150 of pregnancy) and equine fetal testis (day 180 of pregnancy). In the fetal ovary, positive c...
Edens LM, Crisman MV, Toth TE, Ahmed SA, Murray MJ.The objectives of this study were to: (1) develop a technique to analyze the in vitro cytotoxic activity of lymphocytes from adult horses against equine herpesvirus-1 (EHV-1) infected allogenic equine dermal fibroblasts (EDF); (2) evaluate the ability of a 72-h in vitro incubation with interleukin-2 (IL-2) to enhance the lymphocytic cytolytic activity against EHV-1 infected EDF; (3) compare the cytotoxic activity of lymphocytes isolated from pregnant mares and non-pregnant mares against EHV-1 infected EDF; (4) ascertain if any correlations existed between the percent cytotoxicity and percentag...
Rogers PA, Fahey GC, Albert WW.Serum amino acid profiles and other serum characteristics of broodmares and their foals wee studied. Compared with mares, foals had significantly higher concentrations of serum leucine, threonine, aspartic acid, asparagine, glutamic acid, glutamine, proline and tyrosine, glucose, cholesterol, creatinine and phosphorus. Foals had significantly less serum histidine, glycine, cystine, taurine, protein and urea nitrogen. Lysine and/or methionine supplementation of pregnant and lactating broodmare diets were conducted. Changes in serum amino acid profiles caused by dietary amino acid supplemented w...
Yurdaydin N, Tekin N, Gülyüz F, Aksu A, Klug E.An Arab broodmare herd of 30 mares age ranging from 4 to 12 years was grouped into 3 groups (group A, B, C) with 10 mares each and exposed to three different methods of cycle synchronisation. Group A mares received two PGF2 alpha injections 14 days apart. Group B mares got additionally 2,500 IU of hCG 5 days after second prostaglandin application. Group C consisted of mares which had foaled in a synchrony of one week and got a PGF2 alpha injection 3 weeks after parturition. All the mares responding to synchronisation were inseminated closely to ovulation detected by serial rectal palpations wi...
Raz T, Amorim MD, Stover BC, Card CE.The objective of this study was to compare the efficacy of purified equine- and porcine-FSH treatment regimes in mares in early vernal transition. Mares (n = 22) kept under ambient light were examined ultrasonographically per-rectum, starting January 30th. They were assigned to one of two treatment groups using a sequential alternating treatment design when a follicle >or= 25 mm was detected. In the eFSH group, mares were treated twice daily with equine-FSH, and in the pFSH group mares were treated twice daily with porcine-FSH; treatments were continued until follicle(s) >or= 35 mm, and 24 h l...
Williams GL, Amstalden M, Blodgett GP, Ward JE, Unnerstall DA, Quirk KS.Three experiments were conducted during the operational breeding season to confirm that continuous, subcutaneous infusion of low-dose GnRH would not disrupt established estrous cycles (Experiment 1), and test the hypotheses that a similar treatment would stimulate secretion of LH and induce development of ovulatory follicles in persistently anovulatory mares (Experiments 2 and 3). Treatment with GnRH (5 microg/h) increased (P<0.001) serum P4 during the luteal phase (7.7+/-0.5 versus 6.4+/-0.5 ng/mL), tended to increase serum LH (2.6+/-0.27 versus 1.9+/-0.25 ng/mL), and did not modify intero...
Glatzel PS, Kangasniemi A, Belz JP, Lange A.The investigations were done on 108 mares (78 warm-blooded horses, 25 cold-blooded horses and 5 trotters). To pursue the question in the title, progesterone and estradiol values in jugular vein-blood were examined starting from 30 days before the calculated date of parturition until 30 days after that event. In parallel to that Ca/Mg ratio was measured by means of a semiquantitative test-strip in the milk. Clinical signs of the birth, parturition itself and the post partum period were recorded. In respect to the P4 and E2 values it was that the P4:E2 ratio changed towards parturition in favour...
Cougouille-Gauffreteau B, Jussiaux M, Trillaud C.The androgenization of a more belonging to a social group where it held a stable hierarchic rank, or a mare recently admitted to this group, increases their status in the hierarchic order and the position acquired is subsequently maintained; in some cases, they continue to rise in the hierarchic order long after the injections of male hormones has been stopped. Some elements of the social behaviour of a stallion appear during the treatment; these elements may persist long after the mares have regained their female hormone balance, corroborated by the establishment of a standard pregnancy.
Lantz KC, Enders AC, Liu IK.In addition to the unique feature of retention of unfertilized ova, the oviducts of mares frequently contain large intraluminal masses with a fibrillar component and some cells. The aim of this study was to identify the cells and examine their relationship to the extracellular components of these masses. Intraluminal masses were examined both in situ and flushed from the oviducts. The nature of the contained cells and their relationship to the fibrils were examined by light microscopy and by transmission and scanning electron microscopy. In some mares the large masses distended the oviduct, bu...
