Mares and horses are integral components of equine studies, focusing on the reproductive and behavioral aspects of equine biology. Mares, or adult female horses, play a significant role in breeding programs and are often studied for their reproductive physiology, gestation, and maternal behaviors. Horses, as a broader category, encompass both sexes and all age groups, providing a comprehensive view of equine anatomy, physiology, and behavior. Research in this area often investigates the differences and similarities between mares and other horses in terms of hormonal cycles, reproductive health, and social interactions. This page compiles peer-reviewed studies and scholarly articles that explore the biological and behavioral characteristics of mares and horses, offering insights into their roles in equine science and management.
ROWLANDS IW.Shortly after Cole & Hart [1930] had reported the discovery of a gonadotrophic hormone in the blood of the mare in early pregnancy they [Cole, Howell & Hart, 1931] described the changes that occur in the ovaries throughout gestation, and associated the unusually active condition of the ovaries between the 40th and 150th day with the presence of the gonadotrophin in the blood. During this period the ovaries are very large and contain numerous follicles and a small number of functional corpora lutea. The authors claim that the latter serve initially to supplement the function of the primary corp...
Salcedo-Jiménez R, Kenney DG, Dubois MS.This case series reports four late pregnancy broodmares that were diagnosed with bladder rupture. The initial presentations were abdominal discomfort (n = 3) and dystocia (n = 1). All mares (n = 4) were overdue or at their expected time of delivery. Three mares showed clinical signs related to bladder rupture: pollakiuria (n = 2) and hematuria (n = 1). At the time of diagnosis, three mares had increased peritoneal fluid creatinine, the mean peritoneal: serum creatinine ratio was 4.1, and the bladder tear was observed via cystoscopy in 3 cases. Two mares were discharged from the hospital. Compl...
Fischetti L, Perina F, Sarli G, Ellero N, Freccero F, Castagnetti C, Mariella J.A 286-day pregnant mare was referred for signs of impending abortion. The ultrasonographic evaluation revealed a high normal combined thickness of the utero-placental unit (CTUP), oligohydroallantois and a living fetus. No vulvar discharge was observed, and the cervical swab culture was negative. After a choke, the mare received NSAIDs and antibiotics and then developed systemic inflammatory response syndrome (SIRS) and aborted. The amniotic portion of the umbilical cord was excessively long and twisted and the chorionic side of the placenta showed a brown discoloration and rough surface area....
Bailey CS, Beachler TM, Mochel JP, Wulf LW, Yaeger M, Kundu D, Withowski K, Papich MG.Despite their widespread clinical use, there is limited pharmacokinetic data for many equine intrauterine antimicrobials. This study aimed to measure the concentration of gentamicin and penicillin in the uterine fluid of mares following infusion of either a standard (PPGent) or long-acting (LA-PPGent) compounded formulation. We hypothesized that both formulations would result in therapeutic concentrations, with total concentrations sustained for longer using the long-acting formulation. Mares were administered 2400 mg of procaine penicillin and 200 mg of gentamicin via a single intrauterin...
Lection J, Schnobrich M, Wagner B, Byron M, Back B, Rollins A, Castro Alves RF, Cheong SH, Diel de Amorim M.To evaluate inflammatory cytokine and chemokine concentrations in endometrial samples collected by cytobrush or swab as a potential screening diagnostic marker for equine endometritis. Unassigned: 88 mares had endometrial samples collected, which included cytobrush, swab, and/or biopsy. Clinical reproductive records, reproductive ultrasound examination, endometrial cytology and culture results, and biopsy grading score were recorded. Fluorescent bead-based multiplex assays for the inflammatory markers interferon-γ, interferon-α, IL-1β, IL-4, IL-10, IL-17A, soluble CD14, tumor necrosis facto...
Neto ME, Curcio BR, Rafael LA, Pivato GM, Silva GC, Souza RP, Mousquer MA, Nogueira CEW.The cesarian section (C-section) is a potential risk factor for retained fetal membranes (RFM) in mares, requiring prompt diagnosis and treatment to enhance outcomes. This study aimed to evaluate the use of umbilical vessel infusion for the treatment of RFM after elective C-section in mares. Ten pregnant criollo type-mares at 315 days of gestation were monitored daily and underwent elective C-section upon readiness for birth. All mares exhibited RFM, with placentas retained beyond three hours careful extraction of the foal by C-section. Those were randomly assigned into two groups: Umbilical v...
Merari A, Fielding L.To describe patient characteristics, laboratory data, fetal orientation, methods of correction, survival, and treatment in miniature equids with dystocia. Methods: Retrospective study conducted from January 2002 to June 2023. Methods: Equine referral hospital and field service. Methods: Seventy animals with a total of 78 instances of dystocia. Methods: None. Results: Recorded variables included signalment, clinicopathologic data, fetal presentation, correction method, survival to discharge, and complications. The survival of miniature equid mares was 94% (73/78), while survival of foals was 17...
Atayde MF, Vidondo B, Bruckmaier R, Freymond SB, Sieme H, Rey-Kaeser R, Burger D.In-hand breeding involving restraint methods is likely the most common practice in the horse breeding industry worldwide. However, welfare issues that arise from such management have not been investigated in detail. Objective: (1) To investigate whether the mares show increased stress responses during in-hand breeding using (a) a lip twitch and (b) hobbles. (2) To evaluate if the use of restraint methods influences the mare's expression of oestrous behaviour. Methods: Intra-individual cross-over design. Methods: Six Franches-Montagnes stallions and 10 warmblood mares were used in these experim...
Hedia M, Leroy JLMR, Loomans S, Benedetti C, Angel-Velez D, Chiers K, Govaere J, Van Soom A, Smits K.Lipopolysaccharide (LPS) in follicular fluid impairs steroid production and oocyte developmental competence in cows and mice. This study assessed LPS concentrations in equine follicular fluid and their association with steroid and some cytokine levels. Additionally, we evaluated whether LPS exposure during in vitro maturation (IVM) affects equine oocyte developmental competence. In experiment 1, follicular fluid from large follicles (>30 mm in diameter) was collected from 16 slaughterhouse mares, and concentrations of LPS, estradiol, progesterone, TNF-α, and IL-6 were measured. In experiment...
Carey KJ, Smith I, Hartley CA, Bailey KE, McIntosh K, Broder CC, Gilkerson JR.Hendra virus (HeV) is a high consequence pathogen that causes severe respiratory and/or neurological disease in both horses and humans with high mortality. The equine vaccine, Equivac® HeV, is a recombinant soluble version of the G glycoprotein of HeV (HeV-sG) that elicits a potent HeV-neutralising antibody response in adult horses and also provides indirect protection for humans. Maternally derived HeV-G specific antibodies could interfere with subsequent foal vaccination, although other factors such as foal age and the suitability of vaccination protocols that have been optimised for adult ...
Sharshar A, Hammad A, Salem M, El-Sunsafty M.This study was carried out to evaluate a rectal pull-back one-stage technique, which is a modification of the one-stage Goetz technique, for treating third-degree perineal laceration or rectovestibular fistula. Methods: This study was performed on 12 mares, ten of whom suffered from third-grade perineal laceration, and two suffered from rectovestibular fistula and were included in this study. After incision of the vestibular shelf horizontally, the dissected rectal flap was pulled caudally and sutured to the anal sphincter during its reconstruction at the final stage. While the vestibular shel...
Motta D, Pedrosa J, Lilenbaum W.Leptospirosis is a zoonotic disease caused by pathogenic bacteria of the genus Leptospira. A lesser-known form, equine genital leptospirosis (EGL), has been identified as a chronic and often silent infection involving the colonisation of the mare's genital tract. Despite its potential impact, EGL remains underdiagnosed and poorly understood, particularly in its association with reproductive inefficiency. This study showed the presence of Leptospira spp. DNA by lipL32-PCR in the genital tract of mares with a history of reproductive disturbances. Cervicovaginal mucus samples were collected from ...
Samsel J, Gündemir O, Szara T, Witkowski M.Uterine torsion in mares belongs to maternal pregnancy disorders, accounting for 5-10% of complications in the last trimester of pregnancy. Two surgical techniques for repositioning uterine torsion are used: flank laparotomy in local anesthesia on a standing mare (SFL) and midline laparotomy carried out under general anesthesia (MI). The study aims to present the exact protocol used by the authors to qualify a mare with uterine torsion for surgery using one of the above-mentioned methods.A total of 19 mares were operated on, of which 13 underwent midline laparotomy under general anesthesia, an...
Muderspach ND, Daucke R, Nielsen MW, Scoggin KE, Fedorka CE, Miller LMJ, May MG, Troedsson MHT, Ferreira-Dias G, Agerholm JS, Schoof EM....Endometrial fibrosis leads to subfertility when periglandular fibrosis impairs endometrial gland function. Identifying distinct protein expressions in mares suffering from this condition is essential for understanding the pathogenesis and developing treatments to delay fibrotic progression. To gain a better understanding of protein dynamics underlying this condition, Data-Independent Acquisition Mass Spectrometry was utilized to comprehensively characterize and compare the equine endometrial and plasma proteome from mares with different severities of endometrial fibrosis. Mares in diestrus wer...
Alfatlawy HJ. in Arabian mares poses a significant reproductive challenge, necessitating proper pathogen identification and antimicrobial susceptibility determination. Unassigned: To investigate the prevalence of intrauterine pathogens and their antimicrobial susceptibility patterns in Arabian mares with postbreeding endometritis. Unassigned: Seventeen Arabian mares were examined clinically and ultrasonographically. Uterine swabs were collected for bacterial isolation and antimicrobial susceptibility testing. Unassigned: Clinical endometritis was detected in 29.4% of the mares. Ultrasonographic examination...
Moore HL, Klabnik JL, Boothe DM, Cruz-Espindola C, Mita N, Thungrat K, Babu RJ, Lyman CC.To investigate the IV pharmacokinetic parameters of clomiphene citrate (CC), a selective estrogen receptor modulator, in mares. Unassigned: This was an experimental study to assess the pharmacokinetic parameters of CC in the mare. Eight mares received a single 2,000-mg dose of IV CC to identify plasma concentrations over 336 hours. Following this, 6 mares received a multidose regimen of IV CC (2,000 mg, q 24 h) for 5 days to identify trough plasma concentration each day. Unassigned: CC was well tolerated, demonstrated a short elimination half-life of 4.95 ± 1.10 hours and a mean residence tim...
Thomé C, Márquez-Moya A, Sala-Ayala L, Carreras-Vico N, Cuervo-Arango J.Post-mortem oocyte collection serves to preserve the genetic material of valuable mares and to obtain recipient oocytes for cloning purposes. Therefore, the number of oocytes retrieved per ovary is a critical factor in increasing the likelihood of obtaining a viable embryo. This study evaluated the efficiency of two post-mortem oocyte retrieval techniques: follicular scraping (Scraping) and ultrasound-guided follicular aspiration (OPU). The comparison was based on several parameters, including the number of follicles aspirated per ovary, oocyte recovery rate (ORR), number of oocytes obtained p...
de Lara NSS, Weiss RR, Oba E, Kozicki LE, Souza FA, Bergstein-Galan TG, Muehlbauer E, Silvestri M, de Lima PHL, Vaz ES.In equine reproduction, determining foetal sex is of economic and strategic importance, but currently available methods are often invasive, costly, or require specialised expertise. This study aimed to assess whether plasma progesterone concentrations could serve as a predictive tool for foetal sex determination in Criollo mares between the 4th and 8th months of gestation and to determine whether these measurements could identify foetal sex. Blood samples were collected at 30-day intervals from 17 Crioula mares between 114 days and 240 days of gestation. Maternal plasma progesterone concen...
Khan Y, Gautier C, Aurich C, El-Shalofy A.Letrozole is a potent and highly selective third-generation aromatase inhibitor. In the present study, we aimed to investigate the effects of letrozole treatment of non-pregnant mares on estrous cycle characteristics. Cyclic, non-lactating mares (n = 9) were included. After estrus synchronization, mares were monitored to detect ovulation (d0:) of the treatment cycle. Each three mares were randomly assigned to one of three treatments: control, 0.5, and 1 mg/kg body weight letrozole in three consecutive cycles (d7 to d13 of the treatment cycle). Mares were inseminated in the estrus after trea...
Roxon CA, Deacon LJ, Abraham M, Stefanovski D, Sertich PL.Gestation length is not a reliable indicator of fetal maturity due to the variability of normal gestation length in the mare. A standard method to accurately predict equine fetal maturity is not being used clinically. The presence of continuous gastrointestinal peristalsis, as detected ultrasonographically, is an indicator that both human and canine fetuses are mature (can survive after elective cesarean section). To determine if continuous gastrointestinal peristalsis, which we termed Phase 5, was a valid indicator of fetal maturity in the horse, and whether this indicator varied in late-gest...
Feijo LS, Ledeck J, Wolfsdorf K, Ponthier J, Parry S, Felippe MJB.Associations between the immune and endocrine systems during equine pregnancy remain poorly understood. Based on the hypothesis that distinct phases of the equine healthy gestation are characterized by specific associations between circulating immunological and hormonal parameters, contributing to pregnancy maintenance, this investigation aimed to: (i) evaluate how circulating immunological and hormonal parameters change across different phases of pregnancy; (ii) investigate associations between changes in circulating immunological and hormonal parameters; and (iii) propose potential hormonal ...
Miguel EL, Carneiro MFL, Griffo ALC, Baatsch Nascimento F, Dória RGS, Corrêa RR, Celeghini ECC.Vaginal varicosities in mares are rarely reported, although considered relatively common. Clinical recognition can be challenging, especially during early pregnancy, due to the intermittent nature of the bleeding. This report aims to describe the diagnostic approach, clinical evolution, and treatment of a case of vaginal varicosity in a pregnant mare, emphasizing a practical and minimally invasive method. A 9-year-old Brazilian Sport Horse mare with intermittent vaginal hemorrhage underwent clinical evaluation, showing no abnormalities. Vaginoscopy with a rigid endoscope revealed varicose vein...
Ali A, Derar DR, Alaeyeari AA, Alharbi YM.This study aimed to monitor intrauterine fetal growth, establish predictive equations for gestational age estimation, and determine the optimal period for fetal sexing in Arabian horses using ultrasonography. Unassigned: Seven Arabian mares were monitored from insemination to parturition using transrectal ultrasonography. The following fetal and embryonic parameters were measured: embryonic vesicle (EV), crown-rump length (CRL), biparietal diameter (BIP), stomach diameter (STD), chest depth (CHD), abdominal diameter (ABD), kidney length (KDL), eyeball diameter (EBD), and eye lens length (ELL)....
Kranenburg LC, Reinke KS, van den Broek J, Zaal EA, van den Boom R, van Doorn DA.Hydrolysed collagen is used as a supplement for horses with osteoarthritis, hoof horn growth problems, and gastric ulcers. To determine the oral availability of a specific hydrolysed collagen supplement and the appropriate dose, six Warmblood mares were fed two different concentrations of the supplement: 100 g HC (C), 50 g HC (C), and a control of 0 g HC (C) during one week in a randomised cross-over design. On day 7, 14 and 21, blood sampling for amino acid (AA) analysis was performed, just prior to feeding the supplement (t = 0) and every hour after feeding for 8 h (t = 1-8). Statistical ana...
Kyle-LaBell E, Andersson A, Baughman B.Fibrocartilaginous embolic myelopathy (FCE) was diagnosed in a 15-year-old pony mare by histopathologic examination of the spinal cord. The horse was euthanized and submitted for necropsy following focal seizures and lateral recumbency for approximately 12 h. Histopathology of spinal cord segments C5-C7 revealed severe ischemic myelomalacia with intravascular amorphous material that stained positive with Alcian Blue, consistent with cartilaginous matrix. These features in addition to the acute onset of clinical signs are characteristic for FCE. This case report describes the clinical and histo...
Broothaers K, Jouneau A, Angel-Velez D, De Coster T, Festuccia N, Archilla C, Calderari S, Jouneau L, Van den Branden E, Peere S, Polfliet E....In vitro production of equine embryos has been performed using intracytoplasmic sperm injection (ICSI) for the last two decades. Since 2022, a repeatable protocol for conventional in vitro fertilization (IVF) provides a successful alternative. However, little is known about the influence of the fertilization method on embryo quality and the transcriptomic profile. In this study, we aimed to examine differentially expressed genes (DEGs) between ICSI and IVF embryos in the horse. Therefore, ten equine sibling blastocysts, produced in vitro by either ICSI or IVF from three different mares, were s...
Silva JA, Vasquetto A, Mouguelar H, Nader-Macías MEF, Pellegrino MS.Equine endometritis, a major cause of subfertility in mares, has a significant economic impact on horse breeding. In the face of rising antimicrobial resistance, the use of beneficial bacteria to prevent this disease is a non-antibiotic alternative which aligns with "One Health" principles. This study characterised vaginal autochthonous lactic acid bacteria (LAB) from healthy mares. Out of the 25 presumptive LAB isolates obtained from 15 clinically healthy thoroughbred mares, 24 were confirmed. Surface properties were assessed (autoaggregation, hydrophobicity, biofilm formation, exopolysacchar...
Sala-Ayala L, Cuervo-Arango J, Martínez Boví R.Endometrial edema is an ultrasonographic sign of estrus in mares and is positively associated with fertility. This study aimed to evaluate the influence of follicular size, systemic progesterone (P4), and exogenous estradiol benzoate (EB) on the onset and duration of endometrial edema. In Experiment 1, anestrus (n = 4) and diestrus mares (n = 4) received 4 mg of EB intramuscularly; edema scores and plasma P4 were monitored over four days. In a complementary group (n = 5), mares were monitored until ovulation, then administered 4 mg of EB and examined every 12 h for 48 h. In Experimen...
Sabzpoosh M, Hoveizi E, Gooraninejad S.This study aimed to extract and isolate endometrial stromal cells from Arabian mares and investigate their growth and differentiation potential. Endometrial biopsies were obtained from three healthy 6-year-old Arabian mares using a standardized, minimally invasive protocol. The isolated cells were characterized using flow cytometry and differentiation analysis. Flow cytometry revealed mesenchymal markers CD90 (95.2%) and CD105 (97.4%) and hematopoietic markers CD34 (1.17%) and CD45 (0.339%). The cells exhibited differentiation potential into adipocytes, osteoblasts, and chondrocytes. The findi...
Tainturier D, Tainturier B, Michaud S, Briand-Amirat L, Topie E, Moreno D.A total of 147 mares of different breeds (110 were sport or race horses, often very valuable) have been monitored over 5 years from 2012 to 2016. When at or near term, the mares were monitored in order to induce foaling, by checking the mammary development by palpation, analysing the colour and consistency of the precolostrum, estimating the calcium and antibodies concentrations in the precolostrum and by measuring the plasmatic progestagens concentration every day at 6 p.m. At the end of gestation, it has been observed that the progestagens rate levelled off (the top concentration varies from...
