Fetal health in horses encompasses the study of the development and well-being of the equine fetus during gestation. This area of research focuses on understanding the physiological processes that occur from conception to birth, including fetal growth, placental function, and maternal-fetal interactions. Factors influencing fetal health can include genetics, nutrition, environmental conditions, and maternal health status. Monitoring fetal health is important for identifying potential complications such as developmental abnormalities or pregnancy loss. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, assessment methods, and implications of fetal health in equine reproduction.
DAVIES J, DEMPSEY EW, WISLOCKI GB.A fetal horse ovary at the 6th month of gestation and a fetal ovary and testis at the 9th month have been studied histochemically with special reference to the cytoplasmic lipids of the interstitial cells. At least two lipid fractions appeared to be present, one which was soluble in acetone and was mainly responsible for the positive "plasmal" reaction, and another, insoluble in acetone, which was responsible for the sudanophilic, Ashbel-Seligman and periodic acid-Schiff positive material remaining after acetone extraction. The interstitial cell lipids in the older ovary and testis were also a...
Gilbert RO, Marlow CH.Records of 1,009 pregnancies in 574 foaling, barren and maiden Thoroughbred mares on a single stud farm, over a period of 12 years were examined. The farm is situated in the eastern Cape Province of South Africa, at an elevation of 1,800 m, and in an area of climatic extremes. Records of 604 pregnancies in 249 foaling Thoroughbred mares were examined. For these purposes, those pregnancies in which a mare conceived in the same breeding season during which she had foaled were considered as pregnancies in foaling mares. Pregnancy was confirmed by rectal palpation by a single experienced practitio...
Saint-Dizier M, Chopineau M, Dupont J, Combarnous Y.The full-length equine luteinizing hormone/chorionic gonadotropin (LH/CG) receptor (eLH/CG-RA) cDNA and two alternatively spliced isoforms (eLH/CG-RB,C) were isolated from luteal tissue and characterized using a combination of reverse transcription-polymerase chain reaction (RT-PCR) and 5'-rapid amplification of cDNA ends. The 680-amino acid full sequence of eLH/CG-RA displayed 87-92% homology with other mammalian LH/CG-Rs. The eLH/CG-RB and eLH/CG-RC cDNA isoforms were truncated from the 3'-end of exon X: eLH/CG-RB spliced out of frame into the last exon whereas eLH/CG-RC contained an in-fram...
Challis JR, Bassett N, Berdusco ET, Han VK, Lu F, Riley SC, Yang K.In domestic ruminants such as the sheep, birth is effected through sequential maturation of the foetal hypothalamic-pituitary-adrenal (HPA) axis, leading to the increased output of cortisol. Factors regulating foetal pituitary adrenocorticotrophin (ACTH) secretion have been delineated, and these include corticotrophin releasing hormone (CRH), arginine vasopressin, prostaglandin (PG) E2 and endogenous opioids. The pre-partum increase in foetal plasma ACTH is associated with a rise in pro-opiomelanocortin (POMC) mRNA in the foetal pars distalis, and with an altered pattern of POMC post-translati...
García-Tamayo J.Clinical findings on Venezuelan Equine Encephalitis virus infection and the teratogenic effects of several Togaviruses are described. Similarities between the intrauterine alterations induced by Venezuelan Equine Encephalitis virus and rubella virus are pointed out. Findings described by Wenger in 1967 were those of massive cerebral necrosis in fetuses of women presumably suffering of encephalitis and they are commented along with the development of an animal experimental model at the end of 1970-1980. Pathogenesis of the intrauterine infection seemed to be related to changes in the placental ...
Rigoglio NN, Smith OE, Matias GSS, Miglino MA, Smith LC.Because of the growing importance of horses in leisure and several sports, somatic cell nuclear transfer (SCNT) is being used more frequently for cloning animals for performance and reproductive purposes. However, because of the need to perforate the zona pellucida during microsurgical reconstruction of the oocyte, it is possible that SCNT-derived embryos undergo premature hatching, resulting in embryo bisection and twinning. Therefore, because equine twin pregnancies often lead to abnormal embryo development and pregnancy failure, we performed a detailed comparative assessment of equine twin ...
Tinel JB, Veras MM, Waked D, Alonso MA, Fernandes CB.Mules are derived from crossing horse mares with a donkey, in which the interest is due to gentleness and ability to work and equestrian sports. As the placenta is responsible for fetal development and maturation, knowing its typical microstructure allows us to understand how fetomaternal interactions occur in this interspecific pregnancy. Thus, the study performed a comparative stereological evaluation of volumetric composition and fetomaternal contact surface in the uterine body (UB), gravid uterine horn (GUH), and nongravid uterine horn (NGUH) of Mangalarga Paulista mare's term allantochori...
Wada R, Fukunaga Y, Kanemaru T, Kondo T.Five pregnant mares, at between 6 and 8 months gestation, were experimentally infected with the Bucyrus strain of equine arteritis virus (EAV). Of the five mares, four aborted and one died. The pathogenesis of the abortions was studied, using histopathologic techniques, tissue immunofluorescence and virus isolation. Common microscopic lesions in the maternal reproductive organs indicated myometritis with a degeneration of the myocytes and an infiltration of the mononuclear cells. Epithelial cells of the endometrial gland showed sporadic degeneration. Lesions in the fetal tissue included an atr...
Webb PD.The pituitary glands of 4 horse embryos (41-55 days of gestation) were examined by light microscopy, and the pars distalis from 10 fetal foals (75-300 days) was examined by electron microscopy. At Day 41 the development of Rathke's pouch and the saccus infundibuli was advanced; the former had almost lost its connection with the stomodaeum and the latter had started to differentiate into infundibular process and infundibular stalk. By Day 43 Rathke's pouch was completely dissociated from the stomodaeum and its walls were beginning to show uneven growth. The ventral wall of the pouch, the future...
Pascoe RR.A total of 2187 Thoroughbred and Standardbred mares was examined over a 4-year period to determine the location of the fetus at 42 days, the location of the previous fetus as determined by examination 5-15 days after foaling, and pregnancy location the next season. Maiden mares showed 44 and 56% of pregnancies in the left and right horns respectively. No transuterine migration was observed in 139 maiden mares examined after their first foal. Lactating mares showed 62% implantations and full-term pregnancies on one side of the uterus with the next season's pregnancy being in the opposite uterin...
Journée SL, de Ruijter-Villani M, Hendriks WK, Stout TA.Transvaginal ultrasound-guided pregnancy reduction (TUGR) is a procedure described for the management of twins post-fixation in the horse. Success rates are often disappointing but are reported to be more favorable for bilaterally situated twins and when intervention takes place before day 35 of gestation. This study aimed to determine whether stabbing the embryo/fetus rather than aspirating conceptus fluids improved the likelihood of success, measured as the birth of a normal live singleton foal. Data from 103 TUGR interventions were analyzed by logistic regression analysis; method of treatme...
Meintjes M, Graff KJ, Paccamonti D, Eilts BE, Paul JB, Thompson DL, Kearney MT, Godke RA.When aspirating ovarian follicles in pregnant mares to obtain oocytes for in vitro fertilisation (IVF), the effect of the manipulation on circulating concentrations of progesterone may be an important consideration in terms of the maintenance of pregnancy. The object of this study was to compare the effects of 3 different forms of transvaginal ultrasound-guided follicle aspiration (Treatment 1, no aspiration, n = 4; Treatment 2, aspirate only follicles > or =20 mm in diameter, n = 7; Treatment 3, aspirate all visible follicles, n = 7) on peripheral plasma progesterone concentrations between Da...
Uchida M, Addai-Arhin S, Ishibashi H, Hirano M, Fukushima S, Ishibashi Y, Tominaga N, Arizono K.Equine estrogens (EQs) are steroidal hormones isolated from the urine of pregnant mares and are used in the formulation of human medications. This study initially investigated the embryonic developmental toxicity of equilin (Eq) and equilenin (Eqn) in medaka (Oryzias latipes). Malformations were observed in embryos exposed to nominal concentrations of 1 and 10 mg/L of Eq and Eqn. Delayed hatching was observed at 1 mg/L of Eq. To further investigate the molecular mechanism of developmental toxicity caused by Eq and Eqn, transcriptome and bioinformatics analyses were performed. Among 2016 and ...
Barnard K, Leadon DP, Silver IA.Collagen, elastin and structural glycoprotein content of the lungs of 38 fetal and neonatal foals, 8 of which were showing dysmaturity or convulsive syndrome, were measured by standard biochemical means. Glycoprotein content showed little or no change between 100 and 340 days of gestation; elastin remained constant from 100 to about 260 days when there was an exponential increase up to the time of birth, while collagen content rose linearly from 100 days to birth. In dysmature animals there was significantly less collagen in the lungs at birth but the difference in elastin content between the ...
Velineni S, Timoney JF, Artiushin SC, Donahue JM, Steinman M.Foals of mares infected with Leptospira interrogans serovar Pomona type kennewicki (Lk) may be aborted/stillborn or delivered as healthy foals. Is fetal survival explained in part by the immune response of the fetus to Leptospira antigens? Objective: To describe an outbreak of Leptospira abortion in which infected mares delivered dead/sick or normal foals and determine specificities of antibody in a collection of 54 fetuses from similar outbreaks. Methods: Outbreak investigation in combination with a case-control study of a larger set of samples from aborted fetuses. Methods: Serology and poly...
Azuma T, Choi YH, Hochi S, Oguri N.The development of in-vitro matured and microfertilized horse oocytes was examined in vitro. Fertilized oocytes were produced by 20-h insemination of in-vitro matured and partially zona-removed oocytes with frozen spermatozoa that had been treated with caffeine/calcium ionophore A23187 (fertilization rate 34.2%, monospermy rate 76.9%). Embryonic development was assessed by the number of nuclei stained with Giemsa solution. In Experiment 1, a continuous 8-day culture of the microfertilized oocytes in TCM199 or modified synthetic oviduct fluid (m-SOF) supplemented with 10% fetal bovine serum or ...
Hinrichs K, Riera FL, Klunder LR.Embryo transfer was performed in three mares with gonadal dysgenesis. Karyotypes of the mares were as follows: Mare 1, 63,XX, 64,XX, 65,XX; Mare 2, 63,X; and Mare 3, 65,XXX. The mares were administered progesterone in oil, 300 mg intramuscularly daily, starting 1 or 2 days after donor mare ovulation. Embryos were transferred on day 7 after donor ovulation. Mare 1 became pregnant after the first embryo transfer and had a normally developing fetus on necropsy on day 45 of gestation. Mare 3 became pregnant after the third embryo transfer, but the embryo was lost between day 14 and day 18 of gesta...
Nichani AK, Sharma RD, Sarup S.Efficacy of medium RPMI-1640 (supplied by Gibco USA, Centron and Hi-media) supplemented with horse, donkey, sheep and goat sera was evaluated for in vitro propagation of Theileria annulata (Hisar) infected bovine mononuclear cells. The results were compared with the growth rate in RPMI-1640 supplemented with foetal bovine serum (Gibco). RPMI-1640 (Gibco) proved to be the best medium for in vitro cultivation of the parasite infected cells. Foetal bovine serum could be easily, safely and reliably substituted with goat and sheep sera in the growth medium. Horse and donkey sera also gave comparabl...
Wagner LH, Aurich J, Claaßen S, Melchert M, Kaps M, Aurich C.Transrectal and transabdominal ultrasonography is an established method to monitor pregnancy, fetal growth and wellbeing in different species. Growth charts with multiple bio-morphometric parameters to estimate days of gestation and days before parturition exist in small companion animals, sheep and goats, riding type horses and large ponies but not in small horse breeds like Shetland ponies. The aim of this study was to apply fetal biometric assessment and detailed description of physiologic fetal development to mid and late term pregnancies in Shetland mares and to generate reference data fo...
Medina-Bolívar AL, Faleiros RR, Martínez-Aranzales JR.Limited information is available on gastric diseases in neonatal foals as compared with extensive studies in young, adult, and geriatric horses. Reports on fetuses are scarce. Objective: Assess at necropsy stomachs of horse, donkey and mule fetuses in the third trimester of gestation to characterize lesions present during intrauterine life. Methods: Forty-six fetal stomachs from both sexes (21 horses, 21 donkeys, and 4 mules) in the third trimester of gestation were collected from a processing plant immediately after slaughter. Methods: Measurements of longitudinal and transverse axes, weight ...
Arroyo E, Whitelock LM, Stanton ME, Stevenson V, de Aguiar LH, Kelleman A.Hydropsical conditions in domestic animals are characterized by abnormal fluid accumulation. While their complete pathophysiology remains unclear, factors such as changes in chorioallantoic membranes, placentitis, or fetal abnormalities may contribute. Hydrops present as a medical emergency that can cause complications for the mare. Early diagnosis and treatment are crucial for the mare's prognosis, as fetal survival is often poor. This report describes a case of hydroallantois in a 9-year-old pregnant Quarter mare at 271 days of gestation, leading to dystocia of a non-viable foal with multipl...
Brito PHS, Ferreira MA, Rusch E, Arantes JA, Carregaro AB, Valadão CAA, Ghantous GF, Dória RGS.Submitting late-term pregnant mares to anesthesia for non-obstetric surgery raises concerns about the survival of the mother and fetus. This study aimed to evaluate and describe transient maternal and fetal hemodynamic changes during general inhalation anesthesia in mares during the last month of gestation. Nine adult mares in the last month of gestation were subjected to general inhalation anesthesia and dorsal recumbency for 90 minutes. Trans-anesthetic vital parameters, arterial hemogasometry, cardiac output, pulmonary arterial pressure, central venous pressure, and fetal heart rates were a...
Fedorka CE, Scoggin KE, Coleman SJ, Hatzel JN, Burleson MD, Troedsson MHT.Alterations during the early stages of embryo development have been associated with long-term effects on the fetus, neonate, and adult, but this has not been investigated in horses. In recent years, intracytoplasmic sperm injection (ICSI) has gained in commercial popularity in the equine population. Research suggests an association between ICSI-produced embryos and placental malformations, but there exists little understanding of the physiology involved. Therefore, we aim to produce a complete transcriptomic analysis of chorioallantois and provide potential pathways that may be impacted follow...
de Castro Sasahara TH, Gomes SP, Abdala FCM, Schimming BC, Miglino MA.Sexual differentiation in the equine fetus involves coordinated morphogenetic processes that shape both the gonads and the genital ducts. Although the formation of testes and ovaries has been relatively well documented, the temporal dynamics and morphometric patterns of the mesonephric (Wolffian) and paramesonephric (Müllerian) ducts remain insufficiently characterized. This study aimed to detail the timeline of gonadal and ductal differentiation in male and female equine fetuses during the critical developmental window between 60 and 80 days of gestation. Gross anatomical evaluation, histo...
Barrantes Murillo DF, Camillo G, Souza Serrano B, Almeida Luciano LP, Castilho Bichara GV, Chaves Vás CA, Furlan Gouvêa FH, Brandini Nespoli PE....Facial abnormalities and brain defects in aborted equine fetuses are rarely reported, and the causes that predispose the occurrence of this condition are difficult to identify. This work reports the morphological and tomographic findings of a case of cryptophthalmia, microphthalmia, oronasal malformation, and hydrocephalus in an aborted equine fetus with umbilical cord torsion in the state of Mato Grosso, Brazil, from a primiparous Quarter Horse female, with 7 months of gestational age. The occurrence of miscarriage was associated with compromised maternal-fetal blood flow due to umbilical cor...
