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Topic:Equine Health

Equine health encompasses the study and management of diseases, disorders, and overall well-being of horses. It involves understanding various physiological systems, preventive care, and treatment strategies to maintain optimal health in equine populations. Common areas of focus include nutrition, infectious diseases, orthopedic conditions, and reproductive health. Research in equine health aims to advance knowledge on diagnostic methods, therapeutic interventions, and management practices that improve horse welfare and performance. This page collects peer-reviewed research studies and scholarly articles that explore the diverse aspects of equine health, offering insights into current findings and advancements in the field.
Why the long face? Comparative shape analysis of miniature, pony, and other horse skulls reveals changes in ontogenetic growth.
PeerJ    September 16, 2019   Volume 7 e7678 doi: 10.7717/peerj.7678
Heck L, Sanchez-Villagra MR, Stange M.Much of the shape variation found in animals is based on allometry and heterochrony. Horses represent an excellent model to investigate patterns of size-shape variation among breeds that were intentionally bred for extreme small and large sizes. Methods: We tested whether ponies (wither height 148 cm, here-after called horses) during ontogenetic growth. We used a dataset of 194 specimens from 25 horse and 13 pony breeds, two of which are miniature breeds (wither height < 96.5 cm)-Falabella, Shetland. We applied three-dimensional geometric morphometrics, linear measurements, and multivariat...
The preliminary studies on protein profile in retained and not retained foetal membranes in heavy draft mares.
Reproduction in domestic animals = Zuchthygiene    September 14, 2019   Volume 54, Issue 12 1543-1551 doi: 10.1111/rda.13561
Wawrzykowski J, Rapacz-Leonard A, Wiącek D, Kankofer M, Janowski T.Protein profile of the placenta expresses its function and maintenance. Any alterations can be reflected in qualitative and quantitative changes in this profile. The aim of the present study was the evaluation of protein profile in the placenta of mares suffering from the retention of foetal membranes (FMR) by two separation methods and the comparison with physiologically released tissues. Placentas from 14 healthy, heavy draft mares were collected immediately after the expulsion of newborn. Tissues after homogenization and staining with fluorescent dyes were subjected to electrophoretic as we...
Water treadmill exercise reduces equine limb segmental accelerations and increases shock attenuation.
BMC veterinary research    September 13, 2019   Volume 15, Issue 1 329 doi: 10.1186/s12917-019-2075-6
Greco-Otto P, Baggaley M, Edwards WB, Léguillette R.Equine water treadmills (WTs) are growing in popularity because they are believed to allow for high resistance, low impact exercise. However, little is known about the effect of water height on limb loading. The aim of this study was to evaluate the effect of water height and speed on segmental acceleration and impact attenuation during WT exercise in horses. Three uniaxial accelerometers (sampling rate: 2500 Hz) were secured on the left forelimb (hoof, mid-cannon, mid-radius). Horses walked at two speeds (S1: 0.83 m/s, S2: 1.39 m/s) and three water heights (mid-cannon, carpus, stifle), ...
Collagens and DNA methyltransferases in mare endometrosis.
Reproduction in domestic animals = Zuchthygiene    September 13, 2019   Volume 54 Suppl 3 46-52 doi: 10.1111/rda.13515
Alpoim-Moreira J, Fernandes C, Rebordão MR, Amaral A, Pinto-Bravo P, Bliebernicht M, Skarzynski DJ, Ferreira-Dias G.Inflammation and fibroproliferative diseases may be modulated by epigenetic changes. Therefore, we suggest that epigenetic mechanisms could be involved in equine endometrosis pathogenesis. DNA methylation is one of the methods to evaluate epigenetics, through the transcription of methyltransferases (DNMT1, DNMT3A, DNMT3B). The correlation between DNMTs and collagen (COL) transcripts was assessed for the different Kenney and Doig's (Current Therapy in Theriogenology. Philadelphia: WB Saunders; 1986) endometrium categories. Endometrial biopsies were randomly collected from cyclic mares. Histolog...
Glucagon-like peptide-1, insulin-like growth factor-1, and adiponectin in insulin-dysregulated ponies: effects of feeding a high nonstructural carbohydrate diet and association with prospective laminitis.
Domestic animal endocrinology    September 13, 2019   Volume 71 106397 doi: 10.1016/j.domaniend.2019.106397
Meier AD, de Laat MA, Reiche DB, Sillence MN.Endocrinopathic laminitis, related to equine metabolic syndrome and insulin dysregulation, causes marked pain and suffering in horses and represents a substantial cost to the horse industry. This study investigated the effect of feeding a diet high in nonstructural carbohydrates on concentrations of active glucagon-like peptide-1 (aGLP-1), total insulin-like growth factor-1 (IGF-1), and high-molecular-weight (HMW) adiponectin, in insulin-dysregulated ponies. Thirty-seven ponies were challenged with this diet for up to 18 d to induce hyperinsulinemia. Hormone concentrations were measured in se...
Effect of permeable cryoprotectant-free vitrification on DNA fragmentation of equine oocyte-cumulus cells.
Reproduction in domestic animals = Zuchthygiene    September 13, 2019   Volume 54 Suppl 3 53-56 doi: 10.1111/rda.13491
Pereira BC, Ortiz I, Dorado JM, Diaz-Jimenez MA, Consuegra C, Gosalvez J, Hidalgo M.DNA fragmentation of cumulus cells could be used as an indicator of oocyte vitrification success as an indirect indicator of the quality of the oocyte. This study was designed to compare the DNA fragmentation of post-mortem equine cumulus cells before or after vitrification in the absence of permeable cryoprotectant agents. Cumulus-oocyte complexes (COCs; n = 56) were recovered from slaughterhouse ovaries and subjected to in vitro maturation (42 hr/38.2°C/5%CO ) before (control group) or after a permeable cryoprotectant-free vitrification method using 1 M sucrose (vitrification group). Af...
Comparative forelimb myology and muscular architecture of a juvenile Malayan tapir (Tapirus indicus).
Journal of anatomy    September 13, 2019   Volume 236, Issue 1 85-97 doi: 10.1111/joa.13087
MacLaren JA, McHorse BK.The absence of preserved soft tissues in the fossil record is frequently a hindrance for palaeontologists wishing to investigate morphological shifts in key skeletal systems, such as the limbs. Understanding the soft tissue composition of modern species can aid in understanding changes in musculoskeletal features through evolution, including those pertaining to locomotion. Establishing anatomical differences in soft tissues utilising an extant phylogenetic bracket can, in turn, assist in interpreting morphological changes in hard tissues and modelling musculoskeletal movements during evolution...
Sperm mitochondrial regulation in motility and fertility in horses.
Reproduction in domestic animals = Zuchthygiene    September 13, 2019   Volume 54 Suppl 3 22-28 doi: 10.1111/rda.13461
Meyers S, Bulkeley E, Foutouhi A.The biological nature of age-related declines in fertility in males of any species, including stallions, has been elusive. In horses, the economic costs to the breeding industry are frequently extensive. Mitochondrial function in ejaculated sperm, which is essential for sperm motility, is reflected by adenosine triphosphate production, mitochondrial oxidative efficiency and production of reactive oxygen species, and that this balance may become compromised in ageing stallions and during the process of cryopreservation. This presentation will focus on mitochondrial integrity and function as an ...
Equid alphaherpesvirus 1 from Italian Horses: Evaluation of the Variability of the ORF30, ORF33, ORF34 and ORF68 Genes.
Viruses    September 13, 2019   Volume 11, Issue 9 851 doi: 10.3390/v11090851
Preziuso S, Sgorbini M, Marmorini P, Cuteri V.This study investigates the genetic variability of the equid alphaherpesvirus type 1 (EHV-1), a virus in horses, by evaluating four specific genes (ORF30, ORF33, ORF34, and ORF68) in Italian horse [...]
The Use of the Water Treadmill for the Rehabilitation of Musculoskeletal Injuries in the Sport Horse.
Journal of veterinary research    September 13, 2019   Volume 63, Issue 3 439-445 doi: 10.2478/jvetres-2019-0050
Muñoz A, Saitua A, Becero M, Riber C, Satué K, de Medina AS, Argüelles D, Castejón-Riber C.In recent years, exercise on a water treadmill has come to have great relevance in rehabilitation and training centres for sport horses. Its use exploits certain physical properties of water, related to the fundamental principles of hydrodynamics, such as buoyancy, viscosity, hydrostatic pressure, and water temperature. These properties together with deliberate specification of the depth of the water and the velocity of the treadmill provide a combination of parameters that can be varied according to the purpose of the rehabilitation or training programme, the disease to rehabilitate, or the h...
Molecular Characterization of Equine Staphylococcus aureus Isolates Exhibiting Reduced Oxacillin Susceptibility.
Toxins    September 13, 2019   Volume 11, Issue 9 535 doi: 10.3390/toxins11090535
Scholtzek AD, Hanke D, Walther B, Eichhorn I, Stöckle SD, Klein KS, Gehlen H, Lübke-Becker A, Schwarz S, Feßler AT.The detection of borderline oxacillin-resistant (BORSA) represents a challenge to both, veterinary and human laboratories. Between 2015 and 2017, 19 equine with elevated minimal inhibitory concentrations for oxacillin were detected in routine diagnostics. The aim of this study was to characterize these isolates to identify factors possibly associated with the BORSA phenotype. All were subjected to antimicrobial susceptibility testing and whole genome sequencing (WGS). A quantifiable β-lactamase activity assay was performed for a representative subset of 13 isolates. The WGS data analysis o...
Cyclical cervical function in the mare involves remodelling of collagen content, which is correlated with modification of oestrogen receptor 1 abundance.
Animal reproduction science    September 12, 2019   Volume 210 106192 doi: 10.1016/j.anireprosci.2019.106192
Campbell MLH, Peachey L, Callan L, Wathes DC, de Mestre AM.This study was conducted to elucidate mare cervical dilation mechanisms by testing two hypotheses: (i) the proportion of collagen staining in histological samples of mare cervices and (ii) the abundance of hormone receptors in the equine cervix differ with stage of the oestrous cycle and site within the cervix. Tissues and jugular vein blood samples were collected from 15 mares. Collagen content was assessed using Masson's Trichome staining. Receptor abundance was assessed using RT-PCR, qRT-PCR and immunohistochemistry. In sub-epithelial stroma, there was less collagen during the follicular th...
Could Pressure Distribution Under Race-Exercise Saddles Affect Limb Kinematics and Lumbosacral Flexion in the Galloping Racehorse?
Journal of equine veterinary science    September 12, 2019   Volume 81 102795 doi: 10.1016/j.jevs.2019.102795
Murray R, Mackechnie-Guire R, Fisher M, Fairfax V.Back pain is frequently recognized in racehorses, but saddle fit and design are rarely assessed. In sport horses, relationships between horse-saddle interaction, back pain, and altered kinematics are established, but few studies investigating horse-saddle interaction in racehorses exist. We hypothesized that reducing pressures under saddles at thoracic (T) vertebrae 10-13 in galloping racehorses is associated with improved limb and lumbosacral kinematics. The objectives of the study were to (1) determine pressure magnitude/distribution under 3 frequently used race-exercise saddles and a saddle...
Synovial butorphanol concentrations and mechanical nociceptive thresholds after intravenous regional limb perfusion in standing sedated horses.
Veterinary surgery : VS    September 12, 2019   Volume 48, Issue 8 1473-1482 doi: 10.1111/vsu.13309
Crabtree NE, Mochal-King CA, Sloan PB, Eddy AL, Wills RW, Meredith AN, Fontenot RL.To determine synovial butorphanol concentrations and mechanical nociceptive threshold (MNT) changes after butorphanol intravenous regional limb perfusion (IVRLP). Methods: Experimental ANIMALS: Six adult horses. Methods: Cephalic IVRLP was performed with 10 mg butorphanol in sedated horses with a wide rubber tourniquet and a total volume of 30 mL. Radiocarpal synovial fluid and serum concentrations along with MNT were evaluated prior to and 0.5, 1, 2, 4, and 6 hours after IVRLP. Butorphanol concentrations were determined with liquid chromatography coupled to tandem mass spectrometry posi...
Cortisol and adrenocorticotropic hormone concentrations in horses with systemic inflammatory response syndrome.
Journal of veterinary internal medicine    September 12, 2019   Volume 33, Issue 5 2257-2266 doi: 10.1111/jvim.15620
Stewart AJ, Hackett E, Bertin FR, Towns TJ.Plasma adrenocorticotropic hormone (ACTH) and serum cortisol concentrations increase with illness-associated stress. Dynamics of plasma ACTH and serum cortisol concentrations in adult horses with systemic illness are undocumented. Objective: To determine whether ACTH and cortisol concentrations and the ACTH/cortisol ratio vary with survival, the presence of systemic inflammatory response syndrome (SIRS), or ischemic gastrointestinal lesions at admission, or throughout hospitalization. Methods: One hundred fifty-one adult horses. Methods: Prospective study measuring serum cortisol and plasma AC...
A method for fatigue testing of equine McIII subchondral bone under a simulated fast workout training programme.
Equine veterinary journal    September 11, 2019   Volume 52, Issue 2 332-335 doi: 10.1111/evj.13163
Shaktivesh , Malekipour F, Whitton C, Lee PVS.Standard fatigue testing of bone uses a single load and frequency applied until failure. However, in situ, the subchondral bone of Thoroughbred racehorses is subjected to a combination (or a spectrum) of loads and frequencies during training and racing. Objective: To investigate the use of a fatigue testing method for equine third metacarpal (McIII) subchondral bone under a spectrum of loading conditions which a racehorse is likely to experience during a fast workout. Methods: In vitro biomechanical experimental study. Methods: McIII subchondral bone specimens (n = 12) of racehorses were ha...
Ameliorative Effect of Ascorbic Acid and Glutathione in Combating the Cryoinjuries During Cryopreservation of Exotic Jack Semen.
Journal of equine veterinary science    September 11, 2019   Volume 81 102796 doi: 10.1016/j.jevs.2019.102796
Kumar P, Kumar R, Mehta JS, Chaudhary AK, Ravi SK, Chandra Mehta S, Ansari MM, Legha RA, Tripathi BN, Talluri TR.The present study was designed to study the adverse effects of cryopreservation and evaluation of the cryoprotective effect of reduced glutathione (GSH) and ascorbic acid (AA) supplementation on exotic jack semen in combination or alone. For this, 24 semen samples from four adult and fertile jacks were collected via artificial vagina using an estrus jenny as dummy. After semen collection, the semen was evaluated for various qualitative and quantitative parameters in fresh, cooled, and frozen-thawed semen. The semen pellet was extended with the freezing extender containing either AA (0.9 g/L),...
Conditioning equine athletes on water treadmills significantly improves peak oxygen consumption.
The Veterinary record    September 11, 2019   Volume 186, Issue 8 250 doi: 10.1136/vr.104684
Greco-Otto P, Bond S, Sides R, Bayly W, Leguillette R.Equine water treadmills (WT) were initially designed for rehabilitation of musculoskeletal injuries, but are also commonly used for conditioning sport horses, however the effects are not well documented. The purpose of this study was to test the effect of an 18-day WT conditioning programme on peak oxygen consumption (V̇O2peak). Nine unfit Thoroughbreds were used in a randomised controlled trial. Six horses worked daily for 18 days in stifle-height water (WT group), while 3 control horses worked without water (dry treadmill group (DT)). Preconditioning and postconditioning maximal exercise ra...
Erratum: Author Correction: Improved reference genome for the domestic horse increases assembly contiguity and composition.
Communications biology    September 11, 2019   Volume 2 342 doi: 10.1038/s42003-019-0591-3
Kalbfleisch TS, Rice ES, DePriest MS, Walenz BP, Hestand MS, Vermeesch JR, O'Connell BL, Fiddes IT, Vershinina AO, Saremi NF, Petersen JL, Finno CJ....[This corrects the article DOI: 10.1038/s42003-018-0199-z.].
Analysis of genetic variation contributing to measured speed in Thoroughbreds identifies genomic regions involved in the transcriptional response to exercise.
Animal genetics    September 11, 2019   Volume 50, Issue 6 670-685 doi: 10.1111/age.12848
Farries G, Gough KF, Parnell AC, McGivney BA, McGivney CL, McGettigan PA, MacHugh DE, Katz LM, Hill EW.Despite strong selection for athletic traits in Thoroughbred horses, there is marked variation in speed and aptitude for racing performance within the breed. Using global positioning system monitoring during exercise training, we measured speed variables and temporal changes in speed with age to derive phenotypes for GWAS. The aim of the study was to test the hypothesis that genetic variation contributes to variation in end-point physiological traits, in this case galloping speed measured during field exercise tests. Standardisation of field-measured phenotypes was attempted by assessing horse...
Differentiation of equine induced pluripotent stem cells into mesenchymal lineage for therapeutic use.
Cell cycle (Georgetown, Tex.)    September 11, 2019   Volume 18, Issue 21 2954-2971 doi: 10.1080/15384101.2019.1664224
Chung MJ, Park S, Son JY, Lee JY, Yun HH, Lee EJ, Lee EM, Cho GJ, Lee S, Park HS, Jeong KS.In previous work, we established an equine induced pluripotent stem cell line (E-iPSCs) from equine adipose-derived stem cells (ASCs) using a lentiviral vector encoding four transcription factors: Oct4, Sox2, Klf4, and c-Myc. In the current study, we attempted to differentiate these established E-iPSCs into mesenchymal stem cells (MSCs) by serial passaging using MSC-defined media for stem cell expansion. Differentiation of the MSCs was confirmed by analyzing expression levels of the MSC surface markers CD44 and CD29, and the pluripotency markers Nanog and Oct4. Results indicated that the E-iPS...
Resiliency of equid H19 imprint to somatic cell reprogramming by oocyte nuclear transfer and genetically induced pluripotency†.
Biology of reproduction    September 11, 2019   Volume 102, Issue 1 211-219 doi: 10.1093/biolre/ioz168
Poirier M, Smith OE, Therrien J, Rigoglio NN, Miglino MA, Silva LA, Meirelles FV, Smith LC.Cell reprogramming by somatic cell nuclear transfer and in induced pluripotent stem cells is associated with epigenetic modifications that are often incompatible with embryonic development and differentiation. For instance, aberrant DNA methylation patterns of the differentially methylated region and biallelic expression of H19-/IGF2-imprinted gene locus have been associated with abnormal growth of fetuses and placenta in several mammalian species. However, cloned horses are born with normal sizes and with no apparent placental anomalies, suggesting that H19/IGF2 imprinting may be epigenetical...
African Horse Sickness: A Review of Current Understanding and Vaccine Development.
Viruses    September 11, 2019   Volume 11, Issue 9 doi: 10.3390/v11090844
Dennis SJ, Meyers AE, Hitzeroth II, Rybicki EP.African horse sickness is a devastating disease that causes great suffering and many fatalities amongst horses in sub-Saharan Africa. It is caused by nine different serotypes of the orbivirus African horse sickness virus (AHSV) and it is spread by Culicoid midges. The disease has significant economic consequences for the equine industry both in southern Africa and increasingly further afield as the geographic distribution of the midge vector broadens with global warming and climate change. Live attenuated vaccines (LAV) have been used with relative success for many decades but carry the risk o...
Racing performance of National Hunt thoroughbred racehorses after treatment of palatal dysfunction with a laryngeal tie-forward procedure and thermocautery of the soft palate with or without aryepiglottic folds resection.
Veterinary surgery : VS    September 10, 2019   Volume 49, Issue 1 114-123 doi: 10.1111/vsu.13321
Koskinen MJ, Virtala AK, McNally T.To assess racing performance of National Hunt thoroughbred (NH) racehorses with a definite diagnosis of palatal dysfunction treated with a laryngeal tie-forward procedure (LTF) and soft palate cautery (SPC) with or without transendoscopic laser excision of the aryepiglottic folds (TLEAF) and to determine correlation between performance measures. Methods: Retrospective cohort study. Methods: National Hunt racehorses treated with LTF, SPC ± TLEAF (n = 44) and nonaffected controls (n = 88). Methods: Performance was evaluated by using Racing Post ratings (RPR), race earnings (RE), and perform...
Molecular identification of vector-borne organisms in Ehrlichia seropositive Nicaraguan horses and first report of Rickettsia felis infection in the horse.
Acta tropica    September 10, 2019   Volume 200 105170 doi: 10.1016/j.actatropica.2019.105170
Tyrrell JD, Qurollo BA, Tornquist SJ, Schlaich KG, Kelsey J, Chandrashekar R, Breitschwerdt EB.Certain vector-borne organisms serve as etiological agents of equine disease. After previously identifying a new Ehrlichia species in horses from Mérida, we aimed to determine the infection frequency and screen for a wide range of vector-borne organisms from 93 tick-exposed, Ehrlichia seropositive horses in this region. PCR assays were performed to identify infection by organisms within the following genera: Anaplasma, Babesia, Bartonella, Ehrlichia, Leishmania, Mycoplasma, Neorickettsia, Rickettsia and Theileria. Overall, 90/93 horses (96.8%) were infected with one or more vector-borne organ...
Optimization and diagnostic evaluation of monoclonal antibody-based blocking ELISA formats for detection of neutralizing antibodies to Hendra virus in mammalian sera.
Journal of virological methods    September 9, 2019   Volume 274 113731 doi: 10.1016/j.jviromet.2019.113731
Di Rubbo A, McNabb L, Klein R, White JR, Colling A, Dimitrov DS, Broder CC, Middleton D, Lunt RA.Maintenance of Hendra virus (HeV) in pteropid bat populations has been associated with spillover events in horses, humans and dogs. Experimental studies have demonstrated infections for several other species including guinea pigs, cats and ferrets. The criteria of a sensitive and specific serological test that is effective for a range of species, but which does not require use of live virus, has not been satisfactorily addressed by currently available tests. We have evaluated the use of two HeV neutralizing monoclonal antibodies (mAbs) in a blocking format enzyme-linked immunosorbent assay (bE...
Ex Vivo Comparison of the Accuracy of a Clamped with a Hand-Held Drill Guide for Drilling Distal Third Metacarpals and Metatarsals in Equids.
Veterinary and comparative orthopaedics and traumatology : V.C.O.T    September 9, 2019   Volume 33, Issue 1 15-21 doi: 10.1055/s-0039-1694972
James OA, Elce Y, Cillán-Garcia E, Reardon RJM. The aim of this study was to determine whether a clamped drill guide can be used effectively to drill across equine distal third metacarpals and metatarsals and to compare accuracy and speed of a drilling with a hand-held drill guide. Methods:  Eighty equine cadaver limbs were divided between four surgeons with varying experience. The limbs were randomly allocated to clamped or hand-held drill guides and placed in a stand in an upright/standing position on a metal table. Drilling times from cis- to trans cortices were measured. Post-drilling computed tomography images were used to assess ...
Evaluation of combined testing to simultaneously diagnose pituitary pars intermedia dysfunction and insulin dysregulation in horses.
Journal of veterinary internal medicine    September 9, 2019   Volume 33, Issue 5 2249-2256 doi: 10.1111/jvim.15617
Horn R, Bertin FR.The thyrotropin-releasing hormone (TRH) stimulation test and the 2-step insulin sensitivity test are commonly used methods to diagnose, respectively, pituitary pars intermedia dysfunction (PPID) and insulin dysregulation (ID). Objective: To investigate the diagnostic value of combining the TRH stimulation test and the 2-step insulin sensitivity test to diagnose PPID and ID simultaneously. Methods: Twenty-seven adult horses, 10 control horses without PPID or ID, 5 horses with PPID only, 5 horses with ID only, and 7 horses with PPID and ID. Methods: Randomized prospective study. Horses underwent...
Perceptions of Whether Stereotypic Off-the-Track Thoroughbreds are Harder to Rehome Than Nonstereotypic OTTBs-A Pilot Survey Study.
Journal of equine veterinary science    September 9, 2019   Volume 81 102794 doi: 10.1016/j.jevs.2019.102794
Wickens C, Arias Esquivel AM, Hendricks C, Heleski C.Several studies have indicated higher incidence of stereotypic behaviors (STBs) in Thoroughbreds. The aftercare of Off-the-Track Thoroughbreds (OTTBs) has received increased attention in the last decade; however, research on the impact of STBs on placement of OTTBs after their racing career is limited. Thoroughbred Aftercare Alliance (TAA) accredits centers throughout North America that work to rehome OTTBs in a safe, welfare-friendly manner. Although the authors have suspected that having an STB would make OTTBs more challenging to rehome, this hypothesis remains to be empirically tested. The...
Equine fetal genotyping via aspiration of yolk-sac fluid at 22-28 days of gestation.
Theriogenology    September 8, 2019   Volume 142 34-40 doi: 10.1016/j.theriogenology.2019.09.012
Ripley AM, Penedo MCT, Grahn RA, Martinez de Andino EV, Walbornn SR, Serafini R, Love CC, Hinrichs K.Fetal genotyping has important applications in the horse, but currently necessitates embryo recovery and biopsy. We investigated whether fetal genotyping could be performed on yolk-sac fluid recovered from pregnant mares via transvaginal aspiration. Fluid was collected before Day 30 to provide results before establishment of the endometrial cups (Day 37). Genotyping and assessment of maternal DNA contamination was performed by analyzing histograms of PCR results for 19 loci. In Exp. 1, mares underwent yolk-sac aspiration on Days 22-28 of gestation. Fluid (0.56-1.02 mL) was recovered from fiv...