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.
Mattei DN, Harman RM, Van de Walle GR, Smith R, Grivel JC, Abdelalim EM, Vinardell T.Mesenchymal stromal cells (MSCs) have regenerative and immunomodulatory potential and may be used to treat injured tissues. Pregnancy has been associated with increased MSCs in the peripheral circulation in multiple species, but to date, there are no reports on this matter in horses. This study aimed to evaluate the effect of pregnancy on isolation efficiency and proliferation capacity of equine MSCs derived from the peripheral blood (PB) of mares. Venous blood samples were collected at the 11th month of gestation and 1 month after delivery from clinically healthy Arabian mares that presented ...
Sielhorst J, Koether K, Volkmann N, Blanco M, Vicioso R, Baade S, Kemper N, de Mestre AM, Sieme H.Little is known about the incidence and outcome of high-risk pregnancies in equine practice and clinical studies on spontaneous occurring placentitis cases and treatments are missing. Therefore, the aims of this retrospective field study were to (1) describe the incidence and severity of ultrasonographic assessed placental abnormalities (UPA) in 4,192 pregnancies on a large commercial warmblood stud farm in 2017 - 2019 and (2) characterize these UPA cases and their pregnancy outcome. UPA severity (Placental abnormality score (PSc) 1-3; low to high), nine treatment regimens (TM1-9) used in UPA ...
Melchert M, Aurich J, Ertl R, Reichart U, Walter I, Gautier C, Kaps M, Aurich C.Mares resume ovarian activity rapidly after foaling. Besides follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the pituitary synthesizes prolactin and growth hormone which stimulate insulin-like growth factor (IGF) synthesis in the liver. We tested the hypothesis that follicular growth is initiated already antepartum, mares with early and delayed ovulation differ in IGF-1 release and that there is an additional IGF-1 synthesis in the placenta. Plasma concentrations of LH, FSH, IGF-1, IGF-2, activin and prolactin. IGF-1, IGF-2, prolactin and their receptors in placental tissues w...
Holmes CM, Babasyan S, Wagner B.The end of gestation, ensuing parturition, and the neonatal period represent highly dynamic phases for immunological changes in both mother and offspring. The regulation of innate immune cells at the maternal-fetal interface during late term pregnancy, after birth, and during microbial colonization of the neonatal gut and other mucosal surfaces, is crucial for controlling inflammation and maintaining homeostasis. Innate immune cells and mucosal epithelial cells express antileukoproteinase (SLPI), which has anti-inflammatory and anti-protease activity that can regulate cellular activation. Unas...
Morris L, Harteveld R, Gibb Z.Insemination of mares with frozen-thawed spermatozoa requires intensive management and results in 40%-60% per cycle pregnancy rates. Objective: To determine if satisfactory fertility is possible for frozen-thawed semen after processing it through a microfluidic device, followed by storage at 17°C for up to 24 h before fixed-time insemination. Methods: Uncontrolled field trials. Methods: A pilot study evaluated the motility of frozen-thawed spermatozoa after centrifugation and storage (17°C) in two different media for up to 48 h. Subsequently, the motility of frozen-thawed semen processed...
Peere S, van Den Branden E, Papas M, Gerits I, Smits K, Govaere J.Twin gestation in the mare is undesirable and can have disastrous consequences. As in many cases, the key to success in twin management lies in a thorough follow-up and accurate recording of clinical findings in the pre-breeding examination. A pregnancy diagnosis in the mobility phase is imperative for a good outcome in the event of twin reduction. If a twin gestation is not diagnosed during this early pregnancy stage, several other procedures exist for managing post-fixation twins (>16 days) with varying degrees of success. Most twin pregnancies are the result of multiple ovulations (dizygo...
Cardiovascular changes have been reported in late pregnancy in mares. However, there are no data on changes in peripheral blood flow. Doppler ultrasound represents a sensitive method for assessing the blood flow directed to the hoof. The aims of this study were to evaluate the blood flow parameters of the lateral palmar digital artery (LPDA) in pregnant mares and to assess intra- and interrater agreement between two observers with different levels of experience. The LPDAs of pregnant Italian Standardbred mares were examined. The vessels were located with B-mode ultrasound and analyzed with col...
Kovacsy S, Ismer A, Funes J, Hoogewijs M, Wilsher S.Equine embryos >300 μm require puncture before vitrification. Protocols that do not require pre-puncture would make vitrification easier and allow for its widespread use. Objective: To design a successful vitrification protocol for embryos >300 μm without puncture as a pre-treatment. Methods: Experimental in vivo study. Methods: Thirty-eight embryos were divided into 3 groups (G1: ≤300 μm, n = 11; G2: >300-500 μm, n = 20; G3: >500 μm, n = 7). Embryos were vitrified using a human vitrification kit. Following a 15 min exposure to equilibration solution ...
Ellerbrock M, Krohn J, Büttner K, Wehrend A.Dystocia typically presents a life-threatening condition for both the mare and the foal. This prospective long-term study aimed to ascertain whether mares with prior pregnancy disorders or a history of dystocia were at a higher risk of experiencing subsequent dystocia in comparison to those without such medical antecedents. To achieve this goal, the authors analysed 207 parturitions and 164 mares over a 10-year period. Of these, 57 were associated with pregnancy disorders or prior dystocia (Group 1), while 150 parturitions followed uneventful pregnancies in mares that had not yet experienced d...
Martínez-Boví R, Sala-Ayala L, Querol-Paajanen A, Plaza-Dávila M, Cuervo-Arango J.PGF is commonly given at the end of embryo flushing (EF) to shorten the interval to the next oestrus and ovulation. Objective: To determine the effect of repeated EF on plasma progesterone concentration, percentage of mares with endometritis, unwanted pregnancy and subsequent fertility in mares flushed without the use of PGF . Methods: Controlled experiments. Methods: Nine mares were inseminated in seven consecutive cycles (n = 63), to either perform an EF (n = 54) 7-9 days after ovulation or left pregnant (n = 9). PGF was not used to induce oestrus. Ultrasound examination and bl...
Sadowska A, Molcan T, Wójtowicz A, Lukasik K, Pawlina-Tyszko K, Gurgul A, Ferreira-Dias G, Skarzynski DJ, Szóstek-Mioduchowska A.The establishment of the fetomaternal interface depends on precisely regulated communication between the conceptus and the uterine environment. Recent evidence suggests that microRNAs (miRNAs) may play an important role in embryo-maternal dialogue. This study aimed to determine the expression profile of endometrial miRNAs during days 26-28 of equine pregnancy. Additionally, the study aimed to predict target genes for differentially expressed miRNAs (DEmiRs) and their potential role in embryo attachment, adhesion, and implantation. Using next-generation sequencing, we identified 81 DEmiRs betwe...
Sielhorst J, Baade S, Neudeck KC, Tönissen A, Rohn K, Hollinshead F, Sieme H.Transvaginal ultrasound-guided aspiration (TUA) is used for post-fixation twin reduction in mares. However, there is limited information regarding factors that influence pregnancy outcome after TUA. Objective: To evaluate the effect of day of gestation on which TUA is performed, aspiration volume, puncture of the conceptus, medication administered before and after TUA, embryo location, mare age and parity and operator experience on pregnancy and foaling rates after TUA. Methods: Retrospective case series. Methods: Data were collected from case records of 464 TUAs performed by 14 operators in 4...
Smith L, Moran AW, Al-Rammahi M, Daly K, Shirazi-Beechey SP.Studies carried out in several species have demonstrated that detection of low-calorie sweeteners in the lumen of the intestine, by the sweet receptor, T1R2-T1R3, initiates a signaling pathway leading to enhanced expression and activity of intestinal Na/glucose cotransporter 1, SGLT1. This results in an increased gut capacity to absorb glucose, sodium chloride and water, the basis for oral rehydration therapy. Horses express T1R2, T1R3 and downstream signaling elements in the intestinal tissue. As such, the potential of sweetener-stimulation of T1R2-T1R3 leading to upregulation of SGLT1 allows...
Delchiaro SB, Oliveira PVLF, Júnior RJP, Gonçalves GD, Morotti F, Seneda MM.Mares (n = 77) were evaluated by antral follicle count (AFC) and selected as embryo recipients. Cyclic recipients received embryos between days 4-6 after ovulation. The acyclic recipients received an intramuscular (i.m.) protocol with 5mg of estradiol benzoate (EB) on the day of donor ovulation (D0; D-4 recipient), 3mg of EB on the following day (D1; D-3 recipient), and 3mg of EB (D2; D-2 recipient). Furthermore, 1500mg of progesterone (P4) i.m. given on D0 of the recipient (D4 donor) followed by 1500mg of P4 on the day of ET (D4-6 recipient). On the ET day, the AFC and animals' weight, body c...
Morrissey J, Pinsky T, Roy MF.Pregnancy loss after Day 40 in mares usually results in the expulsion (abortion) of the fetus and placental membranes. However, fetal retention within the uterus is also a possible outcome, leading to either fetal mummification or maceration. Fetal maceration is septic decomposition of fetal tissues within the uterus following failure of expulsion. It requires the presence of bacteria and oxygen within the uterus, likely originating from an open cervix, and results in tissue autolysis, leaving only fetal bones remaining in the mare. Fetal maceration is a rare complication of pregnancy in mares...
Arnold LC, Stout TAE, Claes ANJ.Management of twin pregnancy after conceptus vesicle fixation in the horse is challenging because the reduction techniques described are either invasive, difficult to perform or associated with disappointing success rates. Objective: To evaluate the success of transrectal ultrasound-guided fetal thorax compression for reducing post-fixation twin pregnancy in mares. Methods: Retrospective clinical study. Methods: Sixteen mares were presented for twin reduction between 51 and 79 days of gestation. History obtained from the owner and/or referring veterinarian detailed information regarding the ...
Köhne M, Hegger A, Tönissen A, Hofbauer L, Görgens A, Sieme H.Bacterial endometritis is a major problem in equine reproduction usually treated with antibiotics, however reports of success rates are scarce. This study collected data from mares diagnosed with intrauterine bacterial growth and compared the outcome of different therapies for bacterial endometritis in German stud farm practice. Data on mares with positive uterine culture results were collected retrospectively in veterinary practices (n = 5; 2018-2022). Information relating to 30 factors (mare, diagnostics, therapy, pregnancy rate) of bacterial endometritis cases (n = 772) were recorded an...
Ren W, Wang J, Zeng Y, Wang T, Meng J, Yao X.Kazakh mares have attracted widespread attention with their outstanding lactation traits. Lactation is a complex dynamic process regulated by multiple factors. The extensive application of transcriptome sequencing technology enables researchers to further explore this biological issue. This study selected three pregnant and three non-pregnant Kazakh mares as the research subject. Their mammary glands were taken for transcriptome sequencing. The results show that there are 9 lncRNAs and 122 mRNAs differentially expressed between the two groups. GO enrichment analysis shows that there are 175 mo...
Lawson JM, Verheyen K, Smith KC, Bryan JS, Foote AK, de Mestre AM.Excessive umbilical cord length (UCL) is associated with equine pregnancy loss. However, a lack of UCL reference values makes it difficult to define excessive UCL. Further, factors associated with differences in UCL are poorly understood. Objective: To (i) report the total, allantoic and amniotic UCL in healthy term pregnancies in Thoroughbreds, (ii) describe the relationship between gestational age and UCL, fetal weight and crown rump length (CRL) using clinically normal pregnancies (CNPs) from mares dying during gestation, and (iii) identify associations between UCL and maternal age and pari...
Lawson JM, Shilton CA, Lindsay-McGee V, Psifidi A, Wathes DC, Raudsepp T, de Mestre AM.Excessive inbreeding increases the probability of uncovering homozygous recessive genotypes and has been associated with an increased risk of retained placenta and lower semen quality. No genomic analysis has investigated the association between inbreeding levels and pregnancy loss. Objective: To compare genetic inbreeding coefficients (F) of naturally occurring Thoroughbred Early Pregnancy Loss (EPLs), Mid and Late term Pregnancy Loss (MLPL) and Controls. The F value was hypothesised to be higher in cases of pregnancy loss (EPLs and MLPLs) than Controls. Methods: Observational case-control st...
Oddsdóttir C, Jónsdóttir HK, Sturludóttir E.Few studies have been conducted on haematological reference intervals (RIs) in Icelandic horses. Reference intervals have been published for Icelandic horses in Austria and a preliminary study in Iceland compared haematological values in riding horses to published RIs for other breeds as well as Icelandic horses abroad. Haematological parameters can vary greatly due to factors such as breed, gender, age, reproductive status, and training, as well as feeding, prior exercise and management method. Icelandic broodmares are kept on pasture under supervision throughout the year, with haylage provid...
Vigolo V, Gautier C, Ertl R, Aurich C, Falomo ME.Subfertility is one of the main issues in horse breeding and the study of mRNAs in sperm might help in elucidating the reasons that lead to this diagnosis. The present study aims at assessing the differences in the expression of 10 potential candidate genes in stallions of different fertility. Frozen-thawed semen of 29 stallions was included. Each sample was classified into two groups according to pregnancy rates (PR) achieved with this semen: "good fertility" (GF; n = 17; PR ≥ 30 %) or "poor fertility" (PF; n = 12; PR <20 %). All stallions underwent a breeding soundness examination ...
Blanco M, Foss R, Tönißen A, Rohn K, Burger D, Sieme H.This retrospective evaluation of data from a large commercial embryo transfer facility aimed to determine the extent to which age and treatment on the day of embryo transfer in recipient mares influence the likelihood of pregnancy. Methods: Embryo recovery was carried out on days 8-10 post-ovulation using transcervical uterine flushing. Recipient mares grouped according to their age were treated once on the day of embryo transfer (Day 3-8 post ovulation) and were assigned randomly to 1 of 3 groups: Mares in Group A (n=101) received antispasmodic, antimicrobial, and anti-inflammatory drugs. Mar...
Robles M, Rousseau-Ralliard D, Dubois C, Josse T, Nouveau É, Dahirel M, Wimel L, Couturier-Tarrade A, Chavatte-Palmer P.In horses, the prevalence of obesity is high and associated with serious metabolic pathologies. Being a broodmare has been identified as a risk factor for obesity. In other species, maternal obesity is known to affect the development of the offspring. This article is a follow-up study of previous work showing that Obese mares (O, n = 10, body condition score > 4.25 at insemination) were more insulin resistant and presented increased systemic inflammation during pregnancy compared to Normal mares (N, n = 14, body condition score < 4 at insemination). Foals born to O mares were more insulin-resi...
Rödel HG, Ibler B, Ozogány K, Kerekes V.Reproduction in young females can show a particularly sensitive response to environmental challenges, although empirical support from individual-based long-term studies is scarce. Based on a 20-year data set from a free-roaming Przewalski's horse population (Equus ferus przewalskii), we studied effects of large-herbivore density (horses + cattle) and weather conditions experienced during different life stages on females' annual birth rates. Foaling probability was very low in 2-year-olds, reaching maximum values in 5 to 10-year-olds, followed by a decrease in older females indicating repro...
Newcombe JR, Wilsher S, Silva ESM, Sala-Ayala L, Cuervo-Arango J.Two experiments were conducted in the Northern (UK) and Southern (Brazil) hemispheres to determine the effect of season (month of conception) on the development of supplementary CL (SCL) and the relationship with pregnancy loss. In experiment 1, 199 pregnancies were followed between Day 14 and term, to determine the number of SCL and pregnancy viability (Northern Hemisphere). From the 199 pregnancies, 178 were obtained from inseminations during the breeding season (March-September), while the rest, 21 pregnancies resulted from conceptions in the non-breeding season (October to February). Pregn...
Christoffersen M, Nielsen SB, Madvig CB, Agerholm JS.Equine pregnancy failure can occur throughout gestation with etiologies varying by region. In Europe, umbilical cord torsion (UCT) has been reported to account for up to 52% of abortions and stillbirths. Little is known about what causes excessive twisting of the umbilical cord (UC), and up till now, only the length of the UC has been identified as a risk factor for UCT. The aim of the present study was to determine the association of potential maternal and fetal risk factors with UCT and umbilical cord length (UCL). A retrospective cohort study was performed on aborted or prematurely delivere...
Szóstek-Mioduchowska A, Wójtowicz A, Sadowska A, Moza Jalali B, Słyszewska M, Łukasik K, Gurgul A, Szmatoła T, Bugno-Poniewierska M....In the current study, transcriptome profiles of mare endometrium, classified into categories I, IIA, and IIB according to Kenney and Doig, were compared using RNA sequencing, analyzed, and functionally annotated using in silico analysis. In the mild stage (IIA) of endometrosis compared to category I endometrium, differentially expressed genes (DEGs) were annotated to inflammation, abnormal metabolism, wound healing, and quantity of connective tissue. In the moderate stage (IIB) of endometrosis compared to category I endometrium, DEGs were annotated to inflammation, fibrosis, cellular home...
Wagner LH, Aurich J, Melchert M, Okada CTC, Gautier C, Kaps M, Claaßen S, Aurich C.High progesterone concentrations in the early luteal phase support pregnancy, whereas subphysiological progesterone concentrations delay embryonic development at least until placentation. In this study, fetal growth and development of pregnancy was investigated in pregnancies with prostaglandin F-induced low progesterone concentrations (PGF) in the early luteal phase and control pregnancies (CON) in the same mares (n = 12). Mares were inseminated and in PGF pregnancies received the prostaglandin F analogue cloprostenol (62.5 µg) on days 0-3 after ovulation to induce subphysiological proges...
Li N, Dai S, Wu H, Zhang F, Song S, Guo Y, Wang S, Chang S, Zeng S.The application of embryo recovery and transfer technology in the donkey industry is far lower than that of horses and cattle. Sometimes the recovered embryos could not be transferred in time, which required embryo cryopreservation. The embryo cryopreservation technology is more conducive to the preservation and transportation of recovered embryos with excellent genetic traits. However, this technique for donkey embryos is not efficient and needs further optimization. The objective of this study was to evaluate the effect of different manual puncture methods on the viability and pregnancy rate...
Barrandeguy M, Parreño V, Lagos Mármol M, Pont Lezica F, Rivas C, Valle C, Fernandez F.Many countries have reported rotavirus diarrhoea in foals. In Argentina it causes important economic losses to the horse industry. In this work we present the results obtained using an experimental vaccine in a farm with enzootic infection of rotavirus. A hundred mares were vaccinated 60 and 30 days before foaling with inactivated rotavirus SA11 (G3P2), H2 (G3P12), Lincoln (G6P1), with aluminum hydroxide as adjuvant; 65 mares were included in the unvaccinated, control group. To evaluate the vaccine, morbidity, duration of the diarrhoea and rotavirus shedding were recorded. Antibody levels were...
Palmer E, Bézard J, Magistrini M, Duchamp G.Since the first successful collection of oocytes by non-surgical puncture, there have been numerous attempts to fertilize them but few segmented embryos have resulted. The latest attempts at follicular puncture (Palmer et al., 1987) provided 159 oocytes. Oocytes found broken (18%) were probably already broken, or at least fragile, before puncture. The 41 oocytes were fertilized only with semen treated with Ionophore A23187. Following ionophore treatment of semen, 16 ova segmented (of 113 inseminated oocytes) indicating fertilization, and another 7 showed signs of fertilization but not segmenta...
Stout TA, Allen WR.A growing equine conceptus must suppress the cyclical release of PGF(2 alpha) from the endometrium to effect maternal recognition of its presence in the uterus. Paradoxically, the conceptus itself secretes PGF(2 alpha), together with other prostaglandins. In this study, the PGF(2 alpha) and PGE(2) content of, and production in vitro by, day 10-32 equine conceptuses were measured and the influence of pregnancy on the concentrations of these prostaglandins in the uterine lumen was examined. In vitro, the release of both prostaglandins per mg conceptus tissue was very high on day 10 after ovulati...
Smith KC, Whitwell KE, Binns MM, Dolby CA, Hannant D, Mumford JA.From 1988 to 1991, 51 pregnant pony mares were challenged intranasally or by aerosol with an isolate of EHV-1 (AB4) originally recovered from a quadriplegic mare. This resulted in 32 abortions, occurring from 9 to 29 days after infection. In 14 of the early abortions (Days 9-14), EHV-1 was not demonstrated in the foetal tissues by virus isolation or immunostaining despite no other non-viral cause for the abortion being evident. Application of the polymerase chain reaction to foetal tissues from 9 of these cases also proved negative. One of the 14 mares was destroyed immediately after abortion,...
Morrell JM, Johannisson A, Dalin AM, Hammar L, Sandebert T, Rodriguez-Martinez H.Artificial insemination is not as widely used in horses as in other domestic species, such as dairy cattle and pigs, partly because of the wide variation in sperm quality between stallion ejaculates and partly due to decreased fertility following the use of cooled transported spermatozoa. Furthermore, predictive tests for sperm fertilising ability are lacking. The objective of the present study was to assess sperm morphology and chromatin integrity in ejaculates obtained from 11 warmblood breeding stallions in Sweden, and to evaluate the relationship of these parameters to pregnancy rates to i...
Bowers S, Gandy S, Anderson B, Ryan P, Willard S.The objective of this study was to investigate use of digital infrared thermal imaging (DITI) to determine whether surface temperature gradient differences exist between pregnant and nonpregnant mares as a noncontact method to determine pregnancy status. On the day measurements were collected, each pregnant mare (n=10; beginning at 292.4+/-1.4 d of gestation) was paired with a nonpregnant mare (n=17). Ambient temperature, DITI measurements (left and right flank, wither temperatures [i.e., animal surface control] and background temperature), and rectal temperatures were obtained every 7 d for 5...
Weber JA, Freeman DA, Vanderwall DK, Woods GL.The hypothesis that treatment of pregnant mares with prostaglandin E2 (PGE2) hastens the oviductal transport of equine embryos was tested by treating bred mares with PGE2 on Day 3 after ovulation and subsequently measuring the rate of hastened oviductal transport (estimated by the uterine embryo recovery rate on Day 4 after ovulation). In a preliminary, noncontrolled experiment, oviductal transport was apparently not hastened after intramuscular, intrauterine, or intraperitoneal PGE2 administration to bred mares (0/6, 0/3, and 0/3 mares, respectively). Oviductal transport appeared to be hasten...
Smith KC, Mumford JA, Lakhani K.Four Welsh Mountain pony mares at 3 months of gestation and one mare at 5 months were inoculated intranasally with equid herpesvirus-1 (EHV-1: Ab4 isolate) at doses of 10(5) to 10(6.6) TCID50. All five mares became infected, but no cases of paresis or abortion occurred. On days 8, 9, 11, 12 (3-month-pregnant mares) and 13 (5-month-pregnant mare) after infection, a detailed examination of the pregnant uterus was made. Small numbers of vascular lesions with EHV-1 antigen expression in endothelial cells were present in the uteri of the early gestational mares; thrombi were rare and foci of thromb...
Madigan JE, Hietala S, Muller N.A 2-year field study was performed to determine the capability of increasing Rhodococcus equi specific antibody in foals via plasma transfusion or mare vaccination, to determine the kinetics of R. equi (ELISA) antibody decay and to assess the protective effects of these procedures in foals on a farm endemic for R. equi. Plasma donors were vaccinated with a killed R. equi bacterin and produced high levels of anti-R. equi antibodies, which were harvested by plasmapheresis. In Experiment 1, 68 foals were given 1 litre of hyperimmune plasma intravenously (i.v.) between 1-60 days of age. Foal plasm...
Sant C, d'Abadie R, Pargass I, Basu AK, Asgarali Z, Charles RA, Georges KC.Equine piroplasmosis caused by Theileria equi and Babesia caballi is endemic in Trinidad and Tobago. Transmission occurs by ticks of the family Ixodidae. T. equi can also be transmitted transplacentally; however transplacental transmission of B. caballi is unknown. This study aims to investigate transplacental transmission of equine piroplasmosis from thoroughbred mares naturally infected via the tick vector. Whole blood and serum samples were collected from 117 mares in the fifth month of pregnancy. Blood samples were also collected from each of their foals (89 in total) within the first 36h ...
Batellier F, Vidament M, Fauquant J, Duchamp G, Arnaud G, Yvon JM, Magistrini M.In the horse industry, milk or milk-based extenders are used routinely for dilution and storage of semen cooled to 4-8 degrees C. Although artificial insemination (AI) with chilled and transported semen has been in use for several years, pregnancy rates are still low and variable related to variable semen quality of stallions. Over the years, a variety of extenders have been proposed for cooling, storage and transport of stallion semen. Fractionation of milk by microfiltration, ultrafiltration, diafiltration and freeze-drying techniques has allowed preparation of purified milk fractions in ord...
Vidament M, Vincent P, Martin FX, Magistrini M, Blesbois E.A suitable method for the cryopreservation of donkey semen would be very valuable for the ex situ management of genetic diversity in this species. This report uses a variety of observation and trials to evaluate the effect of cryoprotectants in per-cycle pregnancy rates (PC) in equids females (jennies (donkey) and mares (horse)). This was explored by (1) comparing the results of insemination of jennies and mares with cooled or frozen donkey semen, (2) examining the possible toxic effect of the cryoprotectant (CPA) glycerol in these two species and (3) studying alternative solutions. Donkey and...
Allen WR.Four separate components combine to produce the progesterone and biologically active 5 alpha-reduced pregnanes needed to maintain pregnancy in the mare. The primary corpus luteum (CL) is prolonged beyond its cyclical lifespan by the down-regulation of endometrial oxytocin receptors to prevent activation of the luteolytic pathway and its waning progesterone production is supplemented from day 40 of gestation by the formation of a series of accessory CL which develop in the maternal ovaries as a result of the gonadotrophic actions of pituitary FSH and the equine chorionic gonadotrophin (eCG). Fr...
Corradetti B, Correani A, Romaldini A, Marini MG, Bizzaro D, Perrini C, Cremonesi F, Lange-Consiglio A.Amniotic membrane-derived mesenchymal cells (AMCs) are considered suitable candidates for a variety of cell-based applications. In view of cell therapy application in uterine pathologies, we studied AMCs in comparison to cells isolated from the endometrium of mares at diestrus (EDCs) being the endometrium during diestrus and early pregnancy similar from a hormonal standpoint. In particular, we demonstrated that amnion tissue fragments (AM) shares the same transcriptional profile with endometrial tissue fragments (ED), expressing genes involved in early pregnancy (AbdB-like Hoxa genes), pre-imp...
Smits K, Nelis H, Van Steendam K, Govaere J, Roels K, Ververs C, Leemans B, Wydooghe E, Deforce D, Van Soom A.The equine oviduct plays a pivotal role in providing the optimal microenvironment for early embryonic development, but little is known about the protein composition of the oviducal fluid in the horse. The aim of the present study was to provide a large-scale identification of proteins in equine oviducal fluid and to determine the effects of ovulation and pregnancy. Four days after ovulation, the oviducts ipsilateral and contralateral to the ovulation side were collected from five pregnant and five non-pregnant mares. Identification and relative quantification of proteins in the oviducal fluid ...
Ginther OJ.Movement of the conceptus within the uterine lumen of barren mares was studied by daily ultrasound examinations on days 11-20 and by rectal palpation on days 15-48 (Experiment 1) and by ultrasound examinations 3 or 4 times per day at 2-4 hour intervals on days 11-16 (Experiment 2). In addition, broodfarm records were analyzed to compare side of ovulation with side of embryo attachment (Experiment 3). The vesicle was found in opposite uterine horns for 43% of the successive, daily, ultrasound examinations on days 11 and 12, 12 and 13, 13 and 14, and 14 and 15; 24% of the successive examinations...
Lane EA, Bijnen ML, Osborne M, More SJ, Henderson IS, Duffy P, Crowe MA.To evaluate factors contributing to fertility of thoroughbred mares, data from 3743 oestrous periods of 2385 mares were collected on a large thoroughbred farm in Ireland. Fourteen stallions (mean age 8.3 years; range 4-15 years) had bred 2385 mares (mean age 9.4 years; range 3-24 years). Maiden mares accounted for 12%, mares with a foal at foot for 64%, and barren, slipped or rested mares for 24% of the total. The mean pregnancy rate per cycle was 67.8% (68.6% in year 1 and 66.9% in year 2). Backward stepwise multivariable logistic regression analysis was utilized to develop two models to eval...
Rizzo M, Ducheyne KD, Deelen C, Beitsma M, Cristarella S, Quartuccio M, Stout TAE, de Ruijter-Villani M.Advanced mare age is associated with declining fertility and an increased risk of early pregnancy loss. Compromised oocyte quality is probably the primary reason for reduced fertility, but the defects predisposing to embryonic death are unknown. In women, advanced age predisposes to chromosome segregation errors during meiosis, which lead to embryonic aneuploidy and a heightened risk of miscarriage. Objective: To evaluate the effect of advanced mare age on chromosome alignment and meiotic spindle morphology in in vitro-matured (IVM) oocytes. Methods: Morphometric and morphological analysis. M...
Nath LC, Anderson GA, McKinnon AO.To evaluate the reproductive efficiency of horse farms in north-east Victoria and identify aspects of management to be targeted for improving reproductive efficiency. Methods: Retrospective study. Methods: Records from seven Thoroughbred (TB) and four Standardbred (STB) studs in north-east Victoria from 1990 to 2001 were reviewed; 8813 cycles in 4455 mares were analysed. TB mares were inseminated by natural mating, whereas STB mares (89%) were artificially inseminated. Results: The overall early pregnancy rate per cycle was 68.8% for TB mares and for STB mares, 68.3%. Multiple pregnancy per cy...
Coutinho da Silva MA, Canisso IF, MacPherson ML, Johnson AE, Divers TJ.Placentitis is a prevalent cause of abortion, premature delivery and neonatal death in mares. Early diagnosis is paramount for the survival of the fetus and delivery of a live foal. Objective: To determine: 1) Serum amyloid A (SAA) profile in healthy mares during late gestation; 2) if placentitis affects SAA concentrations and 3) the effects of therapy on SAA concentrations and pregnancy outcome in mares with placentitis. Methods: In Experiment I, 15 healthy pregnant mares were evaluated from 280 days of gestation to 60 h post partum. In Experiment II, pregnant mares were inoculated intra-cerv...
Ginther OJ, Gastal EL, Gastal MO, Utt MD, Beg MA.The temporal relationships between blood flow in the corpus luteum (CL) and circulating progesterone concentrations were studied in 20 mares. Retrospective inspection of plasma progesterone concentrations indicated that a precipitous decrease occurred during Days 15-17 (Day 0 = ovulation) and was defined as the luteolytic period. Mean percentage of CL with color-Doppler signals for blood flow was maximum on Day 10 (77.3%), and Days 10-14 (49.8%) were defined as the preluteolytic period. The cross-sectional area of the CL decreased progressively from Day 4 (9.0 cm2) to Day 19 (1.5 cm2). Progest...
Adams AP, Antczak DF.A system for transplanting invasive equine trophoblast (i.e., chorionic girdle) to ectopic sites has been developed as a means to study the differentiation of this tissue and to assess maternal immune responses to the conceptus tissue in a site outside the uterus. Chorionic girdle was isolated from Day 33 to 34 conceptuses and surgically placed into the vulvar mucosa or subdermal skin of recipient mares. Biopsy specimens of the graft sites for immunohistochemical staining were taken at weekly or biweekly intervals after grafting. Serum samples were collected from each recipient and tested for ...
Hinrichs K.This paper reviews current equine assisted reproduction techniques. Embryo transfer is the most common equine ART, but is still limited by the inability to superovulate mares effectively. Immature oocytes may be recovered by transvaginal ultrasound-guided aspiration of immature follicles, or from ovaries postmortem, and can be effectively matured in vitro. Notably, the in vivo-matured oocyte may be easily recovered from the stimulated preovulatory follicle. Standard IVF is still not repeatable in the horse; however, embryos and foals can be produced by surgical transfer of mature oocytes to th...
Boerboom D, Brown KA, Vaillancourt D, Poitras P, Goff AK, Watanabe K, Doré M, Sirois J.Luteolysis in domestic species is mediated by the release of luteolytic pulses of prostaglandin (PG) F(2alpha) by the uterus at the end of diestrus, which must be suppressed by the conceptus to permit maternal recognition of pregnancy. In many species, including the horse, both the conceptus and the endometrium also synthesize PGE(2), which may antagonize PGF(2alpha) by playing a luteotropic and/or antiluteolytic role. While the release of PGE(2) and PGF(2alpha) by the equine endometrium in late diestrus and early pregnancy has been previously studied, the underlying prostaglandin synthase gen...
Hartt LS, Carling SJ, Joyce MM, Johnson GA, Vanderwall DK, Ott TL.Uterine function is primarily controlled by the combined actions of oestrogen and progesterone working through their cognate nuclear receptors. The mechanism of establishment of pregnancy in the mare is of interest because it involves prolonged pre-attachment and conceptus migration phases, and both invasive and non-invasive placental cell types, and as such has been an important comparative model. This study characterised regulation of oestrogen (ER) and progesterone (PR) receptors in the endometrium of the mare during the oestrous cycle and early pregnancy. Endometrial tissues collected duri...
Barrier Battut I, Kempfer A, Becker J, Lebailly L, Camugli S, Chevrier L.Several laboratories routinely use flow cytometry to evaluate stallion semen quality. However, objective and practical tools for the on-field interpretation of data concerning fertilizing potential are scarce. A panel of nine tests, evaluating a large number of compartments or functions of the spermatozoa: motility, morphology, viability, mitochondrial activity, oxidation level, acrosome integrity, DNA integrity, "organization" of the plasma membrane, and hypoosmotic resistance, was applied to a population of 43 stallions, 33 of which showing widely differing fertilities (19%-84% pregnancy rat...
Zuidema D, Kerns K, Sutovsky P.Artificial insemination of livestock has been a staple technology for producers worldwide for over sixty years. This reproductive technology has allowed for the rapid improvement of livestock genetics, most notably in dairy cattle and pigs. This field has experienced continuous improvements over the last six decades. Though much work has been carried out to improve the efficiency of AI, there are still many areas which continue to experience improvement, including semen analysis procedures, sperm selection techniques, sperm sexing technologies, and semen storage methods. Additionally, the use ...
