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Topic:Comparative Study

Comparative studies in equine research involve the systematic analysis of different horse breeds, management practices, or physiological responses to identify variations and similarities. These studies are instrumental in understanding how different factors influence health, performance, and behavior in horses. Common areas of comparison include genetic traits, nutritional requirements, disease resistance, and response to training. By evaluating these differences, researchers can develop targeted strategies for breeding, healthcare, and training. This page aggregates peer-reviewed research studies and scholarly articles that focus on the methodologies, findings, and implications of comparative studies in the context of equine science.
Comparison of two analyzers for measurement of plasma total carbon dioxide concentration in horses.
American journal of veterinary research    July 25, 2013   Volume 74, Issue 8 1091-1102 doi: 10.2460/ajvr.74.8.1091
Constable PD, Tinkler SH, Couëtil LL.To determine the degree of agreement between 2 analyzers for measurement of total CO₂ concentration (ctCO₂) in equine plasma. Methods: 6 healthy untrained horses, 6 trained Standardbreds undergoing a simulated race protocol, and 135 trained Standardbreds at a racetrack. Methods: Jugular venous blood samples were obtained from all horses. Two analyzers (commonly used analyzer A and less expensive analyzer B) were used to measure plasma ctCO₂ in each sample. Validation of both analyzers was conducted in accordance with guidelines established by the Clinical and Laboratory Standards Institu...
Effects of ketamine, propofol, or thiopental administration on intraocular pressure and qualities of induction of and recovery from anesthesia in horses.
American journal of veterinary research    July 25, 2013   Volume 74, Issue 8 1070-1077 doi: 10.2460/ajvr.74.8.1070
Ferreira TH, Brosnan RJ, Shilo-Benjamini Y, Moore SB, Hollingsworth SR.To assess the effects of ketamine hydrochloride, propofol, or compounded thiopental sodium administration on intraocular pressure (IOP) and qualities of induction of and recovery from anesthesia in horses. Methods: 6 healthy adult horses. Methods: Horses were sedated with xylazine hydrochloride (0.5 mg/kg), and anesthesia was induced with guaifenesin followed by ketamine (2 mg/kg), propofol (3 mg/kg), or thiopental (4 mg/kg) in a crossover study with ≥ 1 week between treatments. For each horse, IOP in the right eye was measured with a handheld applanation tonometer before and after xylazine ...
Functional limits of agreement applied as a novel method comparison tool for accuracy and precision of inertial measurement unit derived displacement of the distal limb in horses.
Journal of biomechanics    July 23, 2013   Volume 46, Issue 13 2320-2325 doi: 10.1016/j.jbiomech.2013.06.004
Olsen E, Pfau T, Ritz C.Over ground motion analysis in horses is limited by a small number of strides and restraints of the indoor gait laboratory. Inertial measurement units (IMUs) are transforming the knowledge of human motion and objective clinical assessment through the opportunity to obtain clinically relevant data under various conditions. When using IMUs on the limbs of horses to determine local position estimates, conditions with high dynamic range of both accelerations and rotational velocities prove particularly challenging. Here we apply traditional method agreement and suggest a novel method of functional...
Coat color genotypes and risk and severity of melanoma in gray quarter horses.
Journal of veterinary internal medicine    July 22, 2013   Volume 27, Issue 5 1201-1208 doi: 10.1111/jvim.12133
Teixeira RB, Rendahl AK, Anderson SM, Mickelson JR, Sigler D, Buchanan BR, Coleman RJ, McCue ME.Both graying and melanoma formation in horses have recently been linked to a duplication in the STX17 gene. This duplication, as well as a mutation in the ASIP gene that increases MC1R pathway signaling, affects melanoma risk and severity in gray horses. Objective: To determine if melanoma susceptibility in gray Quarter Horses (QH) is lower than gray horses from other breeds because of decreased MC1R signaling resulting from a high incidence of the MC1R chestnut coat color allele in the QH population. Methods: A total of 335 gray QH with and without dermal melanomas. Methods: Blood or hair roo...
Comparison of the lactate minimum speed and the maximal lactate steady state to determine aerobic capacity in purebred Arabian horses.
New Zealand veterinary journal    July 22, 2013   Volume 62, Issue 1 15-20 doi: 10.1080/00480169.2013.815103
Miranda MC, Queiroz-Neto A, Silva-Júnior JR, Pereira MC, Soares OA, Borghi RT, Ferraz GC.To compare five different protocols for estimating the lactate minimum speed (LMS) with that for estimating the maximal lactate steady state (MLSS) in Arabian horses, in order to obtain a more rapid method for monitoring aerobic capacity and prescribing training schedules. Methods: Eight purebred Arabian horses were conditioned to exercise on a treadmill for 12 days then submitted to three to five exercise sessions to determine the MLSS. Blood samples were collected from a jugular catheter at specific intervals for measurement of lactate concentrations. The MLSS was the velocity maintained dur...
Evaluation of conformation against traits associated with dressage ability in unridden Iberian horses at the trot.
Research in veterinary science    July 21, 2013   Volume 95, Issue 2 660-666 doi: 10.1016/j.rvsc.2013.06.017
Solé M, Santos R, Gómez MD, Galisteo AM, Valera M.The work describes and compares the conformation traits and gait characteristics in the main native Iberian dressage Purebreds (Lusitano, Spanish and Menorca horses). In total, 4 strides belonging to each of 66 males (4-14 years old) were recorded at handled trot, using a 3D semi-automatic movement analysis system. Principal component analysis (PCA) and intraclass Correlations (iC) were computed. The Menorca Purebred showed proportionally higher limbs (23.8 and 15.1cm for the forelimb cannon and pastern lengths), the Lusitano Purebred had larger inclinations (66.1°, 37.7° and 47.9° for the ...
Comparison of ultrasonography and histologic examination for identification of ocular diseases of animals: 113 cases (2000-2010).
Journal of the American Veterinary Medical Association    July 20, 2013   Volume 243, Issue 3 376-388 doi: 10.2460/javma.243.3.376
Gallhoefer NS, Bentley E, Ruetten M, Grest P, Haessig M, Kircher PR, Dubielzig RR, Spiess BM, Pot SA.To compare ultrasonographic and histologic examination findings for eyes of animals with ocular diseases. Methods: Retrospective case series. Methods: 116 eyes of 113 animals examined at 2 facilities. Methods: Diseased eyes of animals were examined by means of ultrasonography, removed via enucleation or exenteration, then histologically examined. Ultrasonographic images and histopathologic slides were evaluated, and diseases of eyes were identified with each of those methods and allocated to various categories. For each disease category, agreement between results of ultrasonography and those o...
Analysis of copy number variants by three detection algorithms and their association with body size in horses.
BMC genomics    July 18, 2013   Volume 14 487 doi: 10.1186/1471-2164-14-487
Metzger J, Philipp U, Lopes MS, da Camara Machado A, Felicetti M, Silvestrelli M, Distl O.Copy number variants (CNVs) have been shown to play an important role in genetic diversity of mammals and in the development of many complex phenotypic traits. The aim of this study was to perform a standard comparative evaluation of CNVs in horses using three different CNV detection programs and to identify genomic regions associated with body size in horses. Results: Analysis was performed using the Illumina Equine SNP50 genotyping beadchip for 854 horses. CNVs were detected by three different algorithms, CNVPartition, PennCNV and QuantiSNP. Comparative analysis revealed 50 CNVs that affecte...
Efficacy of cyclo-oxygenase inhibition by two commercially available firocoxib products in horses.
Equine veterinary journal    July 16, 2013   Volume 46, Issue 1 72-75 doi: 10.1111/evj.12095
Barton MH, Paske E, Norton N, King D, Giguère S, Budsberg S.Two firocoxib preparations for oral use are approved for use in animals in many countries: a chewable canine tablet and an equine paste. In order to reduce costs, many veterinarians use the canine product in horses even though this is an off-label use of the preparation. Objective: To determine the relative efficacy of 2 commercially available firocoxib products to inhibit prostaglandin E₂ (PGE2) synthesis after oral dosing in horses. Methods: A crossover design using 8 adult horses (n = 4 for each preparation during each treatment period). Body weight range 532-614 kg. Methods: Horses recei...
Evaluation of a continuous glucose monitoring system compared with an in-house standard laboratory assay and a handheld point-of-care glucometer in critically ill neonatal foals.
Journal of veterinary emergency and critical care (San Antonio, Tex. : 2001)    July 16, 2013   Volume 23, Issue 4 408-415 doi: 10.1111/vec.12072
Hug SA, Riond B, Schwarzwald CC.To evaluate the applicability and accuracy of a continuous glucose monitoring system (CGMS) in critically ill foals by comparing the performance of the CGMS, a point-of-care (POC) glucometer, and an in-house standard laboratory assay (SLA). Methods: Prospective study. Methods: University teaching hospital. Methods: Seven critically ill neonatal foals requiring intensive care. Methods: Foals were instrumented with a CGMS that measured interstitial glucose concentration every 5 minutes for the duration of 15-79 hours. Capillary and venous blood samples were taken every 4-6 hours for POC and SLA...
Use of bovine carpal joints as a training model for cruciate ligament repair.
ANZ journal of surgery    July 15, 2013   Volume 83, Issue 12 933-936 doi: 10.1111/ans.12308
Calvert N, Grainger N, Hurworth M.Currently, there is a lack of cheap and effective training models to allow orthopaedic surgery trainees to learn the basics of anterior cruciate ligament reconstruction. The aim of this paper was to investigate the viability of using various animal joints as models for the training of anterior cruciate ligament reconstruction. Methods: Equine stifles, bovine stifles and carpal joints, sheep stifles and porcine stifles, were sourced from a local abattoir. Each joint was assessed for the following criteria: suitable tendons for harvesting, ease of arthroscopy access, adequacy of arthroscopy view...
Cushioned versus noncushioned centrifugation: sperm recovery rate and integrity.
Theriogenology    July 9, 2013   Volume 80, Issue 6 648-653 doi: 10.1016/j.theriogenology.2013.06.009
Len JA, Beehan DP, Lyle SK, Eilts BE.It was hypothesized that optimal sperm recovery rate (RR) without damage to the sperm would be obtained after centrifugation without a cushion solution. Semen collected three times from six light breed stallions was extended to 25 × 10(6) sperm/mL and centrifuged at CON (noncentrifuged), 900NC (no-cushion), 900C (cushion), 1800NC, and 1800C × g for 10 minutes. Sperm concentration, motility (TM and PM), and intact plasma membranes (PLM) and acrosomes (ACR) pre- and postcentrifugation (D0) and after 24 hours (D1) of cooling were evaluated. The RR in the CON (100 ± 0.0), 900NC (93.7 ± 2.9), a...
Nociceptive thermal threshold testing in horses – effect of neuroleptic sedation and neuroleptanalgesia at different stimulation sites.
BMC veterinary research    July 9, 2013   Volume 9 135 doi: 10.1186/1746-6148-9-135
Poller C, Hopster K, Rohn K, Kästner SB.Aim of the study was to compare the effect of neuroleptic sedation with acepromazine and neuroleptanalgesia with acepromazine and buprenorphine on thermal thresholds (TT) obtained at the nostrils and at the withers. The study was carried out as a randomized, blinded, controlled trial with cross-over design. Thermal thresholds were determined by incremental contact heat applied to the skin above the nostril (N) or the withers (W). Eleven horses were treated with saline (S), acepromazine (0.05 mg/kg) (ACE) or acepromazine and buprenorphine (0.0075 mg/kg) (AB) intravenously (IV). Single stimula...
IHH gene polymorphism among three horse breeds and its application for association test in horses with osteochondrosis.
Hereditas    July 8, 2013   Volume 150, Issue 2-3 38-43 doi: 10.1111/j.1601-5223.2013.02282.x
Zabek T, Golonka P, Fornal A, Semik E.Genetic polymorphism of IHH gene were investigated in Angloarabian, Polish Coldblood and Polish Halfbred horses with the inclusion of a group of Polish Halfbreds affected by osteochondrosis. IHH is a good candidate gene for association study of developmental disorders mainly affecting skeleton development. DNA sequence spanning IHH gene annotated in the horse genome and its putative promoter were investigated using SANGER sequencing. Analysis of genetic variability at polymorphic sites in the IHH gene body and the promoter region confirmed genetic differences between warmblood and coldblood ho...
Breathing pattern and thoracoabdominal asynchrony in horses with chronic obstructive and inflammatory lung disease.
Research in veterinary science    July 6, 2013   Volume 95, Issue 2 654-659 doi: 10.1016/j.rvsc.2013.06.008
Haltmayer E, Reiser S, Schramel JP, van den Hoven R.The aim of the study was to show that changes in thoracoabdominal asynchrony (TAA) between quiet breathing and CO2-induced hyperpnoea can be used to differentiate between horses with healthy airways and those suffering from inflammatory airway disease (IAD) or recurrent airway obstruction (RAO). The level of TAA was displayed by the Pearson's correlation coefficient (PCC) of thoracic and abdominal signals, generated by respiratory ultrasonic plethysmography (RUP) during quiet breathing and hyperpnoea. Changes in TAA were expressed as the quotient of the PCCs (PCCQ) during normal breathing and ...
Comparative genome sequencing identifies a prophage-associated genomic island linked to host adaptation of Lawsonia intracellularis infections.
Veterinary research    July 4, 2013   Volume 44, Issue 1 49 doi: 10.1186/1297-9716-44-49
Vannucci FA, Kelley MR, Gebhart CJ.Lawsonia intracellularis is an obligate intracellular bacterium and the causative agent of proliferative enteropathy (PE). The disease is endemic in pigs, emerging in horses and has also been reported in a variety of other animal species, including nonhuman primates. Comparing the whole genome sequences of a homologous porcine L. intracellularis isolate cultivated for 10 and 60 passages in vitro, we identified a 18-kb prophage-associated genomic island in the passage 10 (pathogenic variant) that was lost in the passage 60 (non-pathogenic variant). This chromosomal island comprises 15 genes dow...
Plasma fructosamine concentrations in horses with pituitary pars intermedia dysfunction with and without laminitis.
Equine veterinary journal    July 4, 2013   Volume 46, Issue 2 249-251 doi: 10.1111/evj.12090
Knowles EJ, Menzies-Gow NJ, Mair TS.Plasma fructosamine concentration ([fructosamine]) is believed to reflect medium term, average blood glucose concentration and in a previous study was higher in horses with active laminitis than in normal horses. Pituitary pars intermedia dysfunction (PPID) is associated with hyperglycaemia and laminitis. Objective: To test the hypotheses that: [fructosamine] is higher in PPID cases than normal animals; furthermore, that within cases of PPID [fructosamine] is higher in those with active laminitis than nonlaminitic cases and in cases that have been affected by active laminitis in the preceding ...
The molecular basis for recognition of bacterial ligands at equine TLR2, TLR1 and TLR6.
Veterinary research    July 4, 2013   Volume 44, Issue 1 50 doi: 10.1186/1297-9716-44-50
Irvine KL, Hopkins LJ, Gangloff M, Bryant CE.TLR2 recognises bacterial lipopeptides and lipoteichoic acid, and forms heterodimers with TLR1 or TLR6. TLR2 is relatively well characterised in mice and humans, with published crystal structures of human TLR2/1/Pam3CSK4 and murine TLR2/6/Pam2CSK4. Equine TLR4 is activated by a different panel of ligands to human and murine TLR4, but less is known about species differences at TLR2. We therefore cloned equine TLR2, TLR1 and TLR6, which showed over 80% sequence identity with these receptors from other mammals, and performed a structure-function analysis. TLR2/1 and TLR2/6 from both horses and hu...
Three slight imprecisions in “Illustrated identification keys to strongylid parasites of Equidae” by Lichtenfels et al. (2008).
Veterinary parasitology    July 3, 2013   Volume 197, Issue 1-2 405-406 doi: 10.1016/j.vetpar.2013.06.017
Stancampiano L, Usai F, Pollio G.No abstract available
Long-term follow-up of atrial function after cardioversion of atrial fibrillation in horses.
Veterinary journal (London, England : 1997)    June 30, 2013   Volume 197, Issue 3 583-588 doi: 10.1016/j.tvjl.2013.05.032
Decloedt A, Verheyen T, Van Der Vekens N, Sys S, De Clercq D, van Loon G.Atrial fibrillation (AF) causes atrial electrical and contractile remodelling in horses. The aim of this study was to quantify left atrial (LA) contractile function and its time course of recovery after cardioversion of naturally-occurring AF in horses. The study population included 42 AF horses which were successfully treated using transvenous electrical cardioversion TVEC (n=39) or quinidine sulfate (n=3), with trivial or mild mitral regurgitation present in 25 horses. Thirty-seven healthy horses were used as controls. AF duration was estimated based on the history and previous examinations....
Development of a real-time PCR to detect Streptococcus equi subspecies equi.
Equine veterinary journal    June 28, 2013   Volume 46, Issue 1 56-59 doi: 10.1111/evj.12088
North SE, Wakeley PR, Mayo N, Mayers J, Sawyer J.Infection with Streptococcus equi subspecies equi (S. equi) is endemic in the UK. A proportion of horses serve as long-term carriers and act as a reservoir of infection. Detection of these persistently infected horses is difficult using standard culture techniques owing to a lack of sensitivity and overgrowth by contaminating bacteria. In addition, differentiation of this causative bacterium from the closely related S. equi zooepidemicus has made the development of reliable and accurate diagnostic tests difficult. Objective: To develop and validate a sensitive and specific real-time PCR assay ...
Effects of intravenous lipopolysaccharide infusion on glucose and insulin dynamics in horses with equine metabolic syndrome.
American journal of veterinary research    June 28, 2013   Volume 74, Issue 7 1020-1029 doi: 10.2460/ajvr.74.7.1020
Tadros EM, Frank N, De Witte FG, Boston RC.To test the hypothesis that glucose and insulin dynamics during endotoxemia differ between healthy horses and horses with equine metabolic syndrome (EMS). Methods: 6 healthy adult mares and 6 horses with EMS. Methods: Each horse randomly received an IV infusion of lipopolysaccharide (20 ng/kg [in 60 mL of sterile saline {0.9% NaCl} solution]) or saline solution, followed by the other treatment after a 7-day washout period. Baseline insulin-modified frequently sampled IV glucose tolerance tests were performed 27 hours before and then repeated at 0.5 and 21 hours after infusion. Results were ass...
Relationship between the Placental Retention Time and the Reproductive Performance at the Foal Heat in Thoroughbred and a Comparison with Heavy Draft.
Journal of equine science    June 28, 2013   Volume 24, Issue 2 25-29 doi: 10.1294/jes.24.25
Ishii M, Aoki T, Yamakawa K, Magata F, Gojo C, Ito K, Kayano M, Nambo Y.The aim of this study was to clarify the relationship between the placental retention time (PRT) and the reproductive performance following mating at the foal heat in Thoroughbreds. For this purpose, we interviewed 292 farmers over a period of 3 years with questionnaires evaluating foaling, expulsion of placenta and reproductive performance at the foal heat in 1,432 mares. The obtained data were later compared with a previous study of heavy draft mares. The average of the PRT of the 1,432 Thoroughbred mares was 58 ± 88 min (mean ± SD). The mean PRT of Thoroughbreds was significantly shorter ...
Arthroscopic optical coherence tomography provides detailed information on articular cartilage lesions in horses.
Veterinary journal (London, England : 1997)    June 28, 2013   Volume 197, Issue 3 589-595 doi: 10.1016/j.tvjl.2013.05.031
te Moller NC, Brommer H, Liukkonen J, Virén T, Timonen M, Puhakka PH, Jurvelin JS, van Weeren PR, Töyräs J.Arthroscopy enables direct inspection of the articular surface, but provides no information on deeper cartilage layers. Optical coherence tomography (OCT), based on measurement of reflection and backscattering of light, is a diagnostic technique used in cardiovascular surgery and ophthalmology. It provides cross-sectional images at resolutions comparable to that of low-power microscopy. The aim of this study was to determine if OCT is feasible for advanced clinical assessment of lesions in equine articular cartilage during diagnostic arthroscopy. Diagnostic arthroscopy of 36 metacarpophalangea...
Intramodality and intermodality agreement in radiography and computed tomography of equine distal limb fractures.
Equine veterinary journal    June 28, 2013   Volume 46, Issue 1 92-96 doi: 10.1111/evj.12082
Crijns CP, Martens A, Bergman HJ, van der Veen H, Duchateau L, van Bree HJ, Gielen IM.Computed tomography (CT) is increasingly accessible in equine referral hospitals. Objective: To document the level of agreement within and between radiography and CT in characterising equine distal limb fractures. Methods: Retrospective descriptive study. Methods: Images from horses that underwent radiographic and CT evaluation for suspected distal limb fractures were reviewed, including 27 horses and 3 negative controls. Using Cohen's kappa and weighted kappa analysis, the level of agreement among 4 observers for a predefined set of diagnostic characteristics for radiography and CT separately...
Morphologic radiographic study of the proximal sesamoid bones of the forelimb in thoroughbred racehorses in training.
Anatomia, histologia, embryologia    June 25, 2013   Volume 43, Issue 5 403-407 doi: 10.1111/ahe.12075
Beccati F, Gialletti R, Giontella A, Davanzo S, Di Meo A, Pepe M.The aim of this study was to identify differences in bone shape (height and width) of proximal sesamoid bones (PSB) in 2-year-old Thoroughbred racehorses in training. Dorsal 15° proximal-palmarodistal oblique images of each metacarpophalangeal joint were acquired before the horses started training and at 1 year after the start of exercise and racing. There were no changes in height and width of PSBs induced by training. There was a significant difference of height and width between medial and lateral PSBs. In both forelimbs, the medial PSB was significantly wider and shorter than the lateral...
Transmission of Streptococcus equi subspecies zooepidemicus infection from horses to humans.
Emerging infectious diseases    June 20, 2013   Volume 19, Issue 7 1041-1048 doi: 10.3201/eid1907.121365
Pelkonen S, Lindahl SB, Suomala P, Karhukorpi J, Vuorinen S, Koivula I, Väisänen T, Pentikäinen J, Autio T, Tuuminen T.Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) is a zoonotic pathogen for persons in contact with horses. In horses, S. zooepidemicus is an opportunistic pathogen, but human infections associated with S. zooepidemicus are often severe. Within 6 months in 2011, 3 unrelated cases of severe, disseminated S. zooepidemicus infection occurred in men working with horses in eastern Finland. To clarify the pathogen's epidemiology, we describe the clinical features of the infection in 3 patients and compare the S. zooepidemicus isolates from the human cases with S. zooepidemicus isolates...
Comparison of the levels of Equus caballus papillomavirus type 2 (EcPV-2) DNA in equine squamous cell carcinomas and non-cancerous tissues using quantitative PCR.
Veterinary microbiology    June 20, 2013   Volume 166, Issue 1-2 257-262 doi: 10.1016/j.vetmic.2013.06.004
Knight CG, Dunowska M, Munday JS, Peters-Kennedy J, Rosa BV.Equus caballus papillomavirus type 2 (EcPV-2) infection has been associated with equine genital squamous cell carcinomas (SCCs). However, quantitative PCR (qPCR) has not been performed to determine viral copy numbers within these lesions. Additionally, the frequency with which EcPV-2 can be detected in other common sites of equine SCC development remains uncertain. The aim of this study was to develop a qPCR assay to estimate the viral load in a variety of equine tissue samples. These included 40 SCC lesions, 19 penile non-SCC or precursor disease lesions, and 222 tissues without observable le...
Comparative analysis of 16S RNA nucleotide sequences of Anaplasma phagocytophilum detected in the blood of horses from various parts of Europe.
Journal of medical microbiology    June 20, 2013   Volume 62, Issue Pt 12 1891-1896 doi: 10.1099/jmm.0.058636-0
Dzięgiel B, Adaszek L, Winiarczyk M, García-Bocanegra I, Carbonero A, Dębiak P, Winiarczyk S.The aim of this study was to conduct a comparative analysis of the 16S rRNA gene fragment nucleotide sequences for Anaplasma phagocytophilum strains detected in the blood of horses from various parts of Europe. The study comprised 234 horses that had had contact with ticks. Using PCR, the genetic material of A. phagocytophilum was identified in the blood of 42 animals. The sequences of the 16S RNA gene amplicons that were obtained from our A. phagocytophilum isolates had 100 % similarity with each other and 96.4-100 % similarity with Anaplasma spp. sequences selected from those available i...
The Responses of Young Domestic Horses to Human-Given Cues.
PloS one    June 19, 2013   Volume 8, Issue 6 e67000 doi: 10.1371/journal.pone.0067000
Proops L, Rayner J, Taylor AM, McComb K.It has been suggested that the process of domestication, at least in some species, has led to an innate predisposition to be skilled at reading human communicative and attentional cues. Adult domestic horses (Equus caballus) are highly sensitive to subtle bodily cues when determining if a person is attending to them but they are less adept at using human communicative cues in object choice tasks. Here we provide the first study into the ontogeny of such skills in order to gain insights into the mechanisms underlying these abilities. Compared with adult horses, youngsters under the age of three...