Topic:Pregnancy
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.
Evaluation of three strip tests for measuring electrolytes in mares’ pre-partum mammary secretions and for predicting parturition. Three strip test kits which measure calcium and/or magnesium in mares' mammary secretions were compared and assessed for their accuracy in:- 1) measuring these electrolytes compared to standard laboratory measurements, and 2) predicting the time of parturition. Daily samples of mammary secretions were obtained pre-partum from 35 Thoroughbred mares and allocated a score. Measurement of mammary secretion calcium and/or magnesium by the strip tests and laboratory methods correlated significantly (P less than 0.001). The results obtained for prediction of parturition were analysed by two methods. ...
Bilateral eyelid swelling attributable to lymphosarcoma in a horse. Bilateral swelling of upper and lower eyelids was caused by lymphocytic infiltration in an 8-year-old Thoroughbred mare. The condition worsened with pregnancy and became associated with subcutaneous dissemination of lymphosarcoma at distant sites.
Plasma prolactin concentrations in mares and their neonates after oxytocin induction of parturition. Studies were undertaken to investigate the effects of oxytocin induction on prolactin release in term (Group II) and preterm (Group III) mares and to compare these effects to spontaneously foaling mares (Group I). Since physiological concentrations of prolactin in blood have not been measured in the neonatal foal, experiments were designed to monitor prolactin in the cord artery and jugular blood of the foals from all groups of mares. Although prolactin levels varied in term mares (Group I and II) during the last 11 days of pregnancy, an increase was observed between Day -6 and Day 0 (2.7 and ...
Plasma plasminogen concentrations in clinically normal horses: the effect of age, sex and pregnancy. Plasma concentrations of plasminogen were determined in 28 clinically normal horses, including 13 adult geldings, five non-pregnant mares, five pregnant mares and five yearlings (two fillies, three geldings). Plasminogen was quantitated by a chromogenic assay based on activation of plasmin by excess urokinase. The overall mean plasma plasminogen for these horses was 2.94 +/- 0.54 CTA units (casein units, as defined by the Committee on Thrombolytic Agents) per ml. There were no significant differences in mean plasma plasminogen values among adult geldings, non-pregnant mares, pregnant mares or ...
Predictive utility of pre-partum temperature changes in the mare. Rectal temperature was recorded from 22 mares at 0700, 1500 and 2300 h daily for seven days pre-partum and one day post partum. A circadian variation in rectal temperature was present with the lowest temperature recorded at 0700 h. Because of this, the mares were divided into three groups based on time of parturition; those foaling between 0700 and 1500 h (n = 2); between 1500 and 2300 h (n = 13); and between 2300 and 0700 h (n = 7). On the day prior to delivery (Day -1) the circadian pattern was absent because the nocturnal increase did not occur. A significant decrease in temperature was rec...
Gamete intrafallopian transfer (GIFT). Gamete intrafallopian transfer (GIFT), developed in 1984, was the result of further studies on in vitro fertilization (IVF). Since that time many nurses have worked in settings near in vitro fertilization centers and, therefore, have a basic understanding of the technology. An overview is given of the GIFT procedure to prepare nurses to advise and refer couples who may qualify for GIFT and to highlight the shift in the fertility program nurse coordinator's functions toward the positions of administrator and consultant.
Surgical removal of one conceptus from fifteen mares with twin concepti. A surgical technique for removal of one conceptus from mares with twin concepti more than 35 days of gestational age was evaluated. One conceptus was removed surgically from each of 15 mares carrying twin concepti that were 41 to 65 days of gestational age. As determined by ultrasonography, eight mares had bicornuate and seven mares had unicornuate twin concepti. For maintenance of pregnancy if surgical trauma should cause prostaglandin release and luteolysis, progesterone was administered prophylactically. Flunixin meglumine was administered perioperatively to minimize prostaglandin release. ...
Efficacy of intrauterine infusion of plasma for treatment of infertility and endometritis in mares. We evaluated the efficacy of intrauterine plasma infusion in mares as a treatment for infertility caused by endometritis and distinguished the effects of intrauterine infusion of plasma vs saline solution. Forty-three subfertile mares were randomly assigned to 1 of 3 treatment groups: untreated controls (n = 14), those treated by saline infusion (n = 14), and those treated by plasma infusion (n = 15). Reproductive status was assessed daily by transrectal ultrasonography. Uterine aspirates and biopsy specimens were obtained 8 days after ovulation for cytologic and histologic evaluation, and mar...
Embryo transfer in subfertile mares. Four subfertile mares (at least 2 barren years) were used as donors in an embryo transfer program. The embryo recovery rate was 50%, varying between 0-100. The transfer of 9 embryos resulted in the pregnancy rate of 44%. The efficiency of embryo transfer using subfertile mares is low. In this material 20% of flushings resulted in a pregnancy. Fyra subfertila ston (gatt galla i minst 2 är) användes som donatorer i ett program för embryot rans fer. Femtio procent av embryon tillvaratogs (varians 0–100%). Transfer av 9 embryon gav en dräktighetsresultat på 44%. Embryotransfer från subfert...
Pharmacological characterization of mare uterus motility with special reference to calcium antagonists and beta-2-adrenergic stimulants. 1. Uterine motility was studied in vitro in the myometrial tissue obtained from pregnant and non-pregnant mares. 2. The spontaneous contractions of the preparations were not modified by tetrodotoxin, by anticholinergics, antiadrenergics, histamine H1 and H2 blockers, antiserotoninergic and opioid antagonists; but disappeared in Ca2+ and Na+ free medium. 3. beta 2-adrenergic stimulants like salbutamol and hexoprenaline and the calcium channel blockers nifedipine and verapamil were effective inhibitors of the amplitude of phasic contractions (ID50S for salbutamol and nifedipine were 7.7 nM and 1...
Maternal immunological recognition of pregnancy in equids. There is little evidence for maternal immunological recognition of pregnancy in most species with the striking exception of the members of the genus Equus. Almost all mares make strong cytotoxic antibody responses to paternally inherited fetal antigens by Day 60 of gestation. Most of these responses are directed against antigens of the Major Histocompatibility Complex (MHC), which constitutes the primary immunogenetic barrier to successful organ transplantation. The source of fetal MHC antigens in the pregnant mare appears to be the specialized trophoblast cells of the chorionic girdle region ...
The continuum of events leading to maternal recognition of pregnancy in mares. Endometria from pregnant mares are able to produce PGF in vitro, but when co-incubated with conceptus membranes the amount and rate of PGF production is considerably reduced. To estimate the molecular weight of conceptus factors that inhibited PGF production, Day-14 conceptus membranes were placed inside bags constructed of dialysis tubing and co-incubated with endometria from Day-14 pregnant mares. PGF production was significantly reduced when membranes were in bags with molecular weight exclusion limits of 12,000, 6000, and 3500, but not of 1000, suggesting that conceptus PGF-inhibitory fact...
The effect of detomidine hydrochloride on the electrical activity of uterus in pregnant mares. The effect of detomidine on the electrical activity of the uterus was studied during the last trimester of pregnancy in 6 mares. The effect was observed in 3-5 min after the i.m. injection and it lasted for 50-70 min. 20 and 40 micrograms/kg b.w. doses of detomidine decreased the myometrial electrical activity, whereas 60 micrograms/kg dose did not have any effect on the activity. The results suggested that 20, 40 and 60 micrograms/kg b.w. doses of detomidine can be administered to mares during the last trimester of pregnancy without the risk of abortion induced by increased uterine electrical...
The nature of embryo reduction in mares with twin conceptuses: deprivation hypothesis. Ultrasonography was used to determine whether there is embryo reduction in mares with unilaterally fixed twins when a major portion of the vascularized area of the wall of one of the embryonic vesicles is in apposition with the wall of the adjacent vesicle, rather than with the endometrium (deprivation hypothesis). In addition, the effect of ovulatory pattern (synchronous and asynchronous) on the incidence of embryo reduction was studied. Twin vesicles were ultrasonically detected on days 11 to 15 (ovulation = day 0) and were examined daily until there was embryo reduction or until day 40. In ...
Survival of day-4 embryos from young, normal mares and aged, subfertile mares after transfer to normal recipient mares. The estimated embryonic loss rate between Days 4 and 14 after ovulation for young, normal mares (9%) was significantly lower (P less than 0.01) than the estimated embryonic loss rate for aged subfertile mares (62%). Fertilization rates, which were based on the recovery of embryos at Day 4 after ovulation, were 96% and 81% (P less than 0.1) for normal and subfertile mares, respectively. Day-4 embryos were collected from the oviducts of normal and subfertile donors mares. These embryos were transferred to the uteri of synchronized, normal recipient mares to test the hypothesis that the high inci...
Transcervical collection of equine conceptuses between 10 and 16 days after ovulation. To recover intact Day-10.5 to Day-16.5 equine conceptuses (Day 0 = ovulation), a rigid catheter was used for 131 collections from donor mares diagnosed pregnant by ultrasonography. A total of 139 conceptuses were recovered, comprising 124 singletons, six pairs of twins and one set of triplets. Of these, 120 (86%) were intact after the collection, 14 (10%) had collapsed, and in five cases (4%), collapsed trophoblastic membranes were surrounded by an intact capsule. The recovery rate of intact conceptuses ranged from 99% on Days 10.5 to 12.5 to 40% on Day 16.5. More uterine flushes per recovery ...
Two related cases of cerebellar abnormality in equine fetuses associated with hydrops of fetal membranes. Hydrops allantois was diagnosed in two Haflinger mares with severe abdominal distension. Both mares were seven months pregnant. Abortion was induced with two injections of prostaglandin six hours apart followed by further manual dilation of the cervix and administration of oxytocin the next day. There were 90 and 95 litres of fluid, respectively, in the allantoic cavities which resembled extracellular fluid with regard to concentrations of urea, creatinine, sodium, potassium, calcium, magnesium, phosphate and chloride, but not total protein. Both fetuses had severe brain abnormalities which we...
The nutritional status of pregnant and non-pregnant mares grazing South East Queensland pastures. It has been reported that the increasing nutritional demands from mid to late pregnancy of grazing mares may not be met when these stages of gestation coincide with pastures being affected by frost. It was established in this study that grass/legume pastures could support the nutritional requirements of brood mares by providing digestible energy intakes of 68.0 and 91.7 MJ/day and digestible nitrogen intake of 91.2 and 138 g/day during mid and late pregnancy, respectively.
An immunochemical demonstration of a pregnancy-specific protein in the horse and its use in the serological detection of early pregnancy. Two-dimensional crossed immunoelectrophoresis of sera from pregnant and non-pregnant horses, using antisera developed against early pregnant mare serum, revealed the presence of two immunologically related proteins one of which appeared to be specific to the pregnant state. This pregnancy-specific protein had beta 2-electrophoretic mobility and was first detectable at Day 6 after successful mating with a stallion. The second protein had gamma 2-electrophoretic mobility and was present in sera from pregnant and non-pregnant horses. The proteins were termed beta 2-horse pregnancy protein and gam...
Variation in plasma concentrations of oestradiol-17 beta and their relationship to those of progesterone, 13,14-dihydro-15-keto-prostaglandin F-2 alpha and oxytocin across pregnancy and at parturition in pony mares. Concentrations of plasma progesterone were similar to values reported in the literature except that a significant decrease in progesterone during the last day, but before parturition, was detected by systematic, high-intensity blood sampling. Mean concentrations of oestradiol-17 beta increased sharply and significantly, plateaued for 132.8 +/- 1.5 days (mean +/- s.e.m., N = 9), then declined sharply in each mare. There was obvious variation between the mares in when these increases and decreases in oestradiol-17 beta occurred, with the events being related closely to ambient photoperiod condit...
In-vitro and in-vivo responsiveness of the corpus luteum of the mare to gonadotrophin stimulation. Dispersed horse luteal cells were used to evaluate the ability of horse LH, hCG and PMSG to stimulate progesterone secretion in vitro. Morphological characterization of these cells before gonadotrophin stimulation indicated the presence of two populations of cells based on cell diameters. In luteal cells incubated as suspended cells, horse LH and hCG stimulated (P less than or equal to 0.05) progesterone production at all levels of treatment. Stimulation of progesterone secretion by hCG was greater (P less than or equal to 0.05) than by horse LH over the range of concentrations utilized. When ...
Restricted conceptus mobility results in failure of pregnancy maintenance in mares. Cycling pony mares were bred and used to test the effect of restricted conceptus mobility on luteal maintenance (i.e. maternal recognition of pregnancy). In Experiment 1, uterine horns were ligated to restrict conceptus mobility to one uterine horn, Group 1; one horn plus the uterine body, Group 2; or one horn, the body and approximately 80% of the second horn, Group 3. Pregnancies were monitored with real-time ultrasonography. Four of five mares in Group 1 and two of four mares in Group 2 returned to estrus (Day 16.0 +/- 1.9 and 14.5 +/- 0.7, respectively) and subsequently lost the embryonic ...
The effect of detomidine (Domosedan) on the maintenance of equine pregnancy and foetal development: ten cases. Detomidine was administered throughout 10 pregnancies in eight mares. An intravenous injection of 20 micrograms/kg body weight was given weekly from Day 14 to Day 60 of gestation and thereafter every four weeks until parturition. One mare suffered torsion of the large colon and was destroyed on Day 86; the foetus was normally developed. A further mare aborted at 167 days. The remaining eight pregnancies continued to full term. One foal was delivered by caesarean section because of torticollis and, of the seven foals born spontaneously, one had bilateral upward patellar fixation at one month ol...
Embryonic loss in mares. Incidence, possible causes, and diagnostic considerations. Fertilization rates were similar for normal and subfertile mares, and much of the difference in fertility between normal and subfertile mares was due to embryonic loss. Fertilization rate estimates for mares ranged from 71 to 96 per cent. The incidence of embryonic loss detected by ultrasonography between Days 11 and 50 was approximately 9 per cent for normal mares, and the estimated incidence of embryonic loss before Day 14 was also 9 per cent. Therefore, the estimated incidence of embryonic loss in normal mares between fertilization and Day 50 is approximately 18 per cent (Fig. 1). In subfer...