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Topic:Horses

"Horses" is a broad topic that encompasses various aspects of equine biology, behavior, and management. This category includes studies on the anatomy, physiology, and genetics of horses, as well as their behavior, nutrition, and care. Research in this area may also cover the historical and cultural significance of horses, their roles in agriculture, sport, and therapy, and the challenges associated with their conservation and welfare. The page aggregates peer-reviewed research articles and scholarly studies that explore the multifaceted relationships between humans and horses, examining both scientific and socio-economic perspectives.
Effects of extracorporeal shock wave therapy and polysulfated glycosaminoglycan treatment on subchondral bone, serum biomarkers, and synovial fluid biomarkers in horses with induced osteoarthritis.
American journal of veterinary research    June 2, 2011   Volume 72, Issue 6 772-779 doi: 10.2460/ajvr.72.6.772
Kawcak CE, Frisbie DD, McIlwraith CW.To evaluate effects of extracorporeal shock wave therapy (ESWT) and polysulfated glycosaminoglycan treatment (PSGAGT) on subchondral bone (SCB), serum biomarkers, and synovial fluid biomarkers in horses with induced osteoarthritis. Methods: 24 healthy 2- to 3-year-old horses. Methods: An osteochondral fragment was created on the distal aspect of the radial carpal bone in 1 middle carpal joint of each horse. Horses were randomly allocated to receive local application of ESWT (days 14 and 28; n = 8), PSGAGT (IM, q 4 d for 28 days; 8), or a sham ESWT probe (placebo; days 14 and 28; 8). Serum biom...
Evaluation of the ability of two transfection reagents to deliver small interfering RNA molecules to equine and guinea pig cartilage in vitro.
American journal of veterinary research    June 2, 2011   Volume 72, Issue 6 813-819 doi: 10.2460/ajvr.72.6.813
Dougherty SS, Santangelo KS, Bertone AL.To evaluate 2 commercially available transfection reagents for transfection efficiency and distribution of small interfering RNA (siRNA) molecules to chondrocytes in monolayer cultures and full-thickness cartilage explants from guinea pigs and horses. Methods: Cartilage explants from 5 one-month-old and 3 adult guinea pigs and 5 adult clinically normal horses. Methods: Monolayer chondrocytes and uniform cartilage explants were exposed to 1 of 2 siRNA transfection complexes according to manufacturers' protocols (1μM [1×]). Additionally, monolayer chondrocytes were exposed to 2× the suggested...
Evaluation of experimentally induced injury to the superficial digital flexor tendon in horses by use of low-field magnetic resonance imaging and ultrasonography.
American journal of veterinary research    June 2, 2011   Volume 72, Issue 6 791-798 doi: 10.2460/ajvr.72.6.791
Karlin WM, Stewart AA, Durgam SS, Naughton JF, O'Dell-Anderson KJ, Stewart MC.To evaluate tendon injuries in horses over a 16-week period by use of ultrasonography and low-field magnetic resonance imaging (MRI). Methods: Tendons of 8 young adult horses. Methods: The percentage of experimentally induced tendon injury was evaluated in cross section at the maximal area of injury by use of ultrasonography and MRI at 3, 4, 6, 8, and 16 weeks after collagenase injection. The MRI signal intensities and histologic characteristics of each tendon were determined at the same time points. Results: At 4 weeks after collagenase injection, the area of maximal injury assessed on cross ...
The use of nylon cable ties to repair rib fractures in neonatal foals.
The Canadian veterinary journal = La revue veterinaire canadienne    June 2, 2011   Volume 52, Issue 3 307-309 
Downs C, Rodgerson D.Commercially available nylon cable ties were used as a method of internal fixation for displaced rib fractures in 8 equine neonates. The procedure was effective, well-tolerated, rapid, and inexpensive. The use of nylon cable ties as internal fixation for displaced rib fractures in foals is an effective surgical procedure. Des attaches en nylon disponibles dans le commerce ont été utilisées comme méthode de fixation interne pour des fractures de côtes déplacées chez 8 nouveau-nés équins. L’intervention a été efficace, bien tolérée, rapide et peu dispendieuse. L’usage d’attac...
Effect of topical vapocoolant spray on response to arthrocentesis and intravenous catheterization in unsedated horses.
American journal of veterinary research    June 2, 2011   Volume 72, Issue 6 746-750 doi: 10.2460/ajvr.72.6.746
Fjordbakk CT, Haga HA.To assess the efficacy of a commercially available topical vapocoolant spray in reducing responses to arthrocentesis of the middle carpal (MC) and metacarpophalangeal (MCP) joints and jugular vein catheterization in unsedated horses. Methods: 8 healthy research horses. Methods: Arthrocentesis of both MC and MCP joints and bilateral jugular vein catheterization were performed in each horse. Immediately prior to skin penetration, 1 randomly selected MC joint, MCP joint, and jugular vein were sprayed with a vapocoolant liquid (intervention product), and the contralateral MC joint, MCP joint, and ...
Impact of successive freezing-thawing cycles on 3-T magnetic resonance images of the digits of isolated equine limbs.
American journal of veterinary research    June 2, 2011   Volume 72, Issue 6 780-790 doi: 10.2460/ajvr.72.6.780
Bolen GE, Haye D, Dondelinger RF, Massart L, Busoni V.To assess the impact of cycles of freezing and thawing on magnetic resonance (MR) images (obtained by use of a 3-T magnet) of equine feet examined ex vivo. Methods: 9 forelimbs from 9 horse cadavers. Methods: 9 forefeet underwent MR imaging first at ambient temperature within 12 hours after the horses' death and then after each freezing-thawing cycle. Three digits underwent freezing and thawing (at 4°C for 36 hours) 2 times, 3 digits underwent freezing and thawing (at 4°C for 36 hours) once and rescanning after 24 hours at ambient temperature, and 3 digits underwent freezing and thawing at a...
The effects of lactated Ringer’s solution (LRS) or LRS and 6% hetastarch on the colloid osmotic pressure, total protein and osmolality in healthy horses under general anesthesia.
Veterinary anaesthesia and analgesia    June 1, 2011   Volume 38, Issue 4 336-343 doi: 10.1111/j.1467-2995.2011.00622.x
Wendt-Hornickle EL, Snyder LB, Tang R, Johnson RA.To investigate changes in colloid osmotic pressure (COP), total protein (TP) and osmolality (OSM) during anesthesia in horses given intravenous lactated Ringer's solution (LRS) or LRS and hetastarch (HES). Methods: Prospective, clinical trial. Methods: Fourteen horses presented for surgery. Mean age 8.3 ± 1.9 years; mean weight 452 ± 25 kg. Methods: Horses were premedicated with xylazine intravenously (IV); anesthesia was induced with ketamine and diazepam IV, and maintained with sevoflurane. Butorphanol was administered IV with pre-medications or immediately after induction. Xylazine was ad...
Characterization of a full-length endogenous beta-retrovirus, EqERV-beta1, in the genome of the horse (Equus caballus).
Viruses    June 1, 2011   Volume 3, Issue 6 620-628 doi: 10.3390/v3060620
van der Kuyl AC.Information on endogenous retroviruses fixed in the horse (Equus caballus) genome is scarce. The recent availability of a draft sequence of the horse genome enables the detection of such integrated viruses by similarity search. Using translated nucleotide fragments from gamma-, beta-, and delta-retroviral genera for initial searches, a full-length beta-retrovirus genome was retrieved from a horse chromosome 5 contig. The provirus, tentatively named EqERV-beta1 (for the first equine endogenous beta-retrovirus), was 10434 nucleotide (nt) in length with the usual retroviral genome structure of 5'...
Impaired efficacy of ivermectin against Parascaris equorum, and both ivermectin and pyrantel against strongyle infections in trotter foals in Finland.
Veterinary parasitology    May 31, 2011   Volume 182, Issue 2-4 372-377 doi: 10.1016/j.vetpar.2011.05.045
Näreaho A, Vainio K, Oksanen A.In order to assess the resistance situation against macrocyclic lactones in Parascaris equorum and against tetrahydropyrimidine derivatives in strongyles in Finnish trotter horses, 112 foals on 18 farms, mostly 1 year old, were examined for these parasites with a modified McMaster faecal flotation method. P. equorum positive foals (n=24) were given ivermectin orally at a dose of 200 μg/kg b.w., while strongyle positive but P. equorum negative foals (n=38) received pyrantel embonate orally at a dose of 19 mg/kg. Sixteen P. equorum infected foals, treated with ivermectin, also harboured strongy...
Comparisons of computed tomography, contrast enhanced computed tomography and standing low-field magnetic resonance imaging in horses with lameness localised to the foot. Part 1: anatomic visualisation scores.
Equine veterinary journal    May 30, 2011   Volume 44, Issue 1 51-56 doi: 10.1111/j.2042-3306.2011.00372.x
Vallance SA, Bell RJ, Spriet M, Kass PH, Puchalski SM.To date, few reports exist comparing magnetic resonance imaging (MRI) and computed tomography (CT) for imaging of the equine distal limb, yet clinicians are required to decide which modality to use regularly. Objective: To report and compare anatomic visualisation scores obtained for CT, contrast enhanced CT (CECT) and standing low-field MRI (LFMRI) in the equine foot. Objective: Anatomic visualisation score discrepancies would exist between CT, CECT and LFMRI. Methods: Images of 22 lame horses (31 limbs) undergoing both CT and LFMRI of the foot were reviewed. When available, CECT images were ...
Effects of chronic acetazolamide administration on gas exchange and acid-base control in pulmonary circulation in exercising horses.
Equine veterinary journal. Supplement    May 28, 2011   Issue 38 40-50 doi: 10.1111/j.2042-3306.2010.00240.x
Vengust M, Stämpfli H, De Moraes AN, Teixeiro-Neto F, Viel L, Heigenhauser G.Carbonic anhydrase (CA) catalyses the hydration/dehydration reaction of CO(2) and increases the rate of Cl(-) and HCO(3)(-) exchange between the erythrocytes and plasma. Therefore, chronic inhibition of CA has a potential to attenuate CO(2) output and induce greater metabolic and respiratory acidosis in exercising horses. Objective: To determine the effects of Carbonic anhydrase inhibition on CO(2) output and ionic exchange between erythrocytes and plasma and their influence on acid-base balance in the pulmonary circulation (across the lung) in exercising horses with and without CA inhibition....
Investigation of the incidence and type of injuries associated with high-speed treadmill exercise testing.
Equine veterinary journal. Supplement    May 28, 2011   Issue 38 70-75 doi: 10.1111/j.2042-3306.2010.00234.x
Franklin SH, Barakzai SZ, Couroucé-Malblanc A, Dixon P, Nankervis KJ, Perkins JD, Roberts CA, Vanerck-Westergren E, Allen KJ.During the past 20 years, treadmill exercise testing has played an important role in both the study of equine exercise physiology and the investigation of poor athletic performance. However, it has been suggested that some trainers and veterinarians may be reluctant to refer horses for treadmill exercise testing because of fears that horses may be at increased risk of musculoskeletal injury during treadmill exercise. Objective: To investigate the incidence and types of injuries sustained by horses undergoing treadmill exercise. Methods: Data were collated from 9 centres in the UK, France and B...
Altered systolic left ventricular function in horses completing a long distance endurance race.
Equine veterinary journal. Supplement    May 28, 2011   Issue 38 216-219 doi: 10.1111/j.2042-3306.2010.00253.x
Amory H, Votion DM, Fraipont A, Goachet AG, Robert C, Farnir F, Van Erck E.It is unknown whether or not exercise-induced cardiac fatigue (EICF), as demonstrated in human athletes performing long duration exercise, occurs in endurance horses. Objective: To examine the effects of a long distance endurance race on left ventricular systolic function in horses. Methods: Echocardiography was performed before, and after, a 2 or 3 star international endurance race (106-132 km) in 11 horses. Systolic (s) and diastolic (d) interventricular and left ventricular free wall thickness (IVS and LVFW, respectively), left ventricular, left atrial and aortic internal diameter (LVID, LA...
Validation and comparison of two methods of measuring lactate in equine plasma.
Equine veterinary journal. Supplement    May 28, 2011   Issue 38 155-160 doi: 10.1111/j.2042-3306.2010.00219.x
Butudom P, Foreman JH, Kline KH, Whittem EL.Some methods of lactate (LA) measurement have not been validated appropriately for use in horses. Objective: To validate 2 LA analysers (YSI 2300 Stat Plus and TDx Lactic Acid Assay) for use with equine plasma and to compare plasma [LA] determined by the 2 methods. Methods: Both instruments were evaluated for linearity, parallelism, recovery and precision using serial dilutions of standard LA solutions and equine plasma and then comparing results with linear regression or paired t tests. Plasma [LA] results were compared in 275 blood samples collected from horses exercising at various intensit...
Cartilage damage involving extrusion of mineralisable matrix from the articular calcified cartilage and subchondral bone.
European cells & materials    May 28, 2011   Volume 21 470-478 doi: 10.22203/ecm.v021a35
Boyde A, Riggs CM, Bushby AJ, McDermott B, Pinchbeck GL, Clegg PD.Arthropathy of the distal articular surfaces of the third metacarpal (Mc3) and metatarsal (Mt3) bones in the Thoroughbred racehorse (Tb) is a natural model of repetitive overload arthrosis. We describe a novel pathology that affects the articular calcified cartilage (ACC) and subchondral bone (SCB) and which is associated with hyaline articular cartilage degeneration. Parasagittal slices cut from the palmar quadrant of the distal condyles of the left Mc3/Mt3 of 39 trained Tbs euthanized for welfare reasons were imaged by point projection microradiography, and backscattered electron (BSE) scann...
Osseous spinal pathology and epaxial muscle ultrasonography in Thoroughbred racehorses.
Equine veterinary journal. Supplement    May 28, 2011   Issue 38 654-661 doi: 10.1111/j.2042-3306.2010.00258.x
Stubbs NC, Riggs CM, Hodges PW, Jeffcott LB, Hodgson DR, Clayton HM, McGowan CM.The multifidus muscle plays a key role in spinal stabilisation. Multifidus atrophy ipsilateral to the side of osseous pathology has been demonstrated in man and pigs but has not been investigated in horses. Objective: To measure cross-sectional area (CSA) left/ right symmetry of equine multifidus ultrasonographically and relate asymmetry of multifidus with osseous spinal pathology in Thoroughbred racehorses. We hypothesised that ipsilateral multifidus CSA would be reduced when osseous pathological changes are present leading to left/right asymmetry in CSA. Methods: Twenty-two racehorses presen...
Inertial sensors for assessment of back movement in horses during locomotion over ground.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 417-424 doi: 10.1111/j.2042-3306.2010.00200.x
Warner SM, Koch TO, Pfau T.Assessing back movement is an important part of clinical examination in the horse and objective assessment tools allow for evaluating success of treatment. Objective: Accuracy and consistency of inertial sensor measurements for quantification of back movement and movement symmetry during over ground locomotion were assessed; sensor measurements were compared to optical motion capture (mocap) and consistency of measurements focusing on movement symmetry was measured. Methods: Six nonlame horses were trotted in hand with synchronised mocap and inertial sensor data collection (landmarks: T6, T10,...
Expression of lactate transporters MCT1, MCT2 and CD147 in the red blood cells of three horse breeds: Finnhorse, Standardbred and Thoroughbred.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 161-166 doi: 10.1111/j.2042-3306.2010.00205.x
Mykkänen AK, Pösö AR, McGowan CM, McKane SA.In exercising horses, up to 50% of blood lactate is taken up into red blood cells (RBCs). Lactate transporter proteins MCT1, MCT2 and CD147 (an ancillary protein for MCT1) are expressed in the equine RBC membrane. In Standardbreds (SB), lactate transport activity is bimodally distributed and correlates with the amount of MCT1 and CD147. About 75% of SB studied have high lactate transport activity in RBCs. In other breeds, the distribution of lactate transport activity is unknown. Objective: To study whether similar bimodal distribution of MCT1 and CD147 is present also in the racing Finnhorse ...
Kinematic characteristics of hoof landing in jumping horses at elite level.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 462-467 doi: 10.1111/j.2042-3306.2010.00187.x
Hernlund E, Egenvall A, Roepstorff L.Biomechanical events of the distal limb during the landing phase of a jump have been proposed to be risk factors for injury, indicating need for further characterisation of the landing and the hoof-surface interaction. This is essential also for valid testing of arena surfaces when simulating actual conditions. Objective: To investigate the hoof landing characteristics for different limbs of elite showjumping horses during the landing phase when jumping 1.30-1.50 m competition fences on 2 different arena surfaces. Methods: A single, fixed high speed camera (1000 frames/s) was aimed at landing ...
Fifty years of the British Equine Veterinary Association as a facilitator of progress in equine clinical science.
Equine veterinary journal    May 27, 2011   Volume 43, Issue 5 618-631 doi: 10.1111/j.2042-3306.2011.00379.x
Silver IA, Jeffcott LB, Rossdale PD.The British Equine Veterinary Association (BEVA) was established in 1961 and launched the Equine Veterinary Journal (EVJ) in 1968. This review outlines some of the major advances in equine science and practice that have occurred in that time and the role played by the Journal in facilitating those developments.
Saddle and leg forces during lateral movements in dressage.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 644-649 doi: 10.1111/j.2042-3306.2010.00201.x
de Cocq P, Mooren M, Dortmans A, van Weeren PR, Timmerman M, Muller M, Van Leeuwen JL.In the equestrian world it is assumed that riders use changes in weight distribution and leg forces as important instruments to give horses directions about speed and direction of movement. However, the changes of these forces have never been quantified. Objective: To investigate the distribution of normal forces (perpendicular to surface) underneath the saddle and of normal forces exerted by the rider's legs during lateral movements. Methods: Eleven riders performed 3 different exercises: riding straight ahead, shoulder-in and travers at trot. Three saddle force systems were used simultaneous...
Single-injection glucose kinetics with compartmental modelling during rest and low-intensity exercise in horses.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 361-369 doi: 10.1111/j.2042-3306.2010.00239.x
Treiber KH, Boston RC, Geor RJ, Hess TM, Harris PA, Kronfeld DS.Tools and criteria to evaluate and understand glucose metabolism are essential to optimise equine energy utilisation for exercise performance and reduced metabolic health risks. Objective: To re-evaluate models of glucose kinetics in the horse at rest and during endurance type exercise using a single injection technique and compartmental modelling. Methods: Twelve exercise trained Arabian geldings received a bolus of 100 µmol/kg bwt [6,6-(2) H]glucose i.v. while at rest and while running at ∼ 4 m/s on a treadmill. Tracer and tracee glucose curves from 4-150 min after the bolus dose (while t...
Assessment of the exercise tests used during overground endoscopy in UK Thoroughbred racehorses and how these may affect the diagnosis of dynamic upper respiratory tract obstructions.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 587-591 doi: 10.1111/j.2042-3306.2010.00281.x
Allen KJ, Franklin SH.Overground endoscopy is being performed with increasing frequency in the UK. A previous study has shown that the type of exercise test may affect the diagnosis of upper respiratory tract (URT) obstructions. The successful clinical application of overground endoscopy systems requires understanding of appropriate field exercise testing protocols. Objective: The aim of this study was to report the exercise test parameters used during overground endoscopy in UK Thoroughbred racehorses and to investigate potential effects of these on the diagnosis of URT obstructions. Methods: The exercise test par...
Evaluation of a mask for breath-by-breath respirometry during exercise in horses.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 240-245 doi: 10.1111/j.2042-3306.2010.00250.x
Ramseyer A, Sides R, Slinker B, Evans D, Bayly W.The ability to obtain breath-by-breath measures of ventilatory mechanics for the entirety of an exercise test, regardless of speed(s) or duration enables evaluations of equine ventilation during exercise that are necessary for assessments of performance. Objective: Evaluation of a new ergospirometer (Quadflow; QF) system's accuracy and repeatability for measuring pulmonary variables in contrast to the established pneumotachometer-based system (control) and assessment of its effects, if any, on exercise capacity at high speeds. Methods: Five Thoroughbred horses each performed 10 incremental exe...
Ground reaction force and kinematic analysis of limb loading on two different beach sand tracks in harness trotters.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 544-551 doi: 10.1111/j.2042-3306.2010.00202.x
Crevier-Denoix N, Robin D, Pourcelot P, Falala S, Holden L, Estoup P, Desquilbet L, Denoix JM, Chateau H.Although beach training is commonly used in horses, limb loading on beach sand has never been investigated. A dynamometric horseshoe (DHS) is well adapted for this purpose. Objective: To compare ground reaction force (GRF) and fetlock kinematics measured in harness trotters on 2 tracks of beach sand with different water content. Methods: Two linear sand tracks were compared: firm wet sand (FWS, 19% moisture) vs. deep wet sand (DWS, 13.5% moisture). Four French trotters (550 ± 22 kg) were used. Their right forelimb was equipped with a DHS and skin markers. Each track was tested 3 times at 7 m/...
Quantification of equine sacral and iliac motion during gait: a comparison between motion capture with skin-mounted and bone-fixated sensors.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 468-474 doi: 10.1111/j.2042-3306.2010.00204.x
Goff L, Van Weeren PR, Jeffcott L, Condie P, McGowan C.Information regarding movement at the ilium and sacrum in nonlame horses during normal gait may assist in understanding the biomechanics of the equine sacroiliac joint. Objective: To determine the amount and direction of motion at the ilium and sacrum using 3D orientation sensors during walk and trot in sound Thoroughbreds. To compare results from sensors fixed to the skin with results from sensors fixed to bone-implanted pins. Methods: Three 3D wireless orientation sensors were mounted to the skin over the tuber sacrale (TS) and sacrum of 6 horses and motion at the ilium and sacrum was record...
Morphological, haemato-biochemical and endocrine changes in young Standardbreds with ‘maladaptation’ to early training.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 171-178 doi: 10.1111/j.2042-3306.2010.00273.x
Leleu C, Haentjens F.The demands in the Standardbred trotters industry require young, still growing horses, to be trained well above light exercise level. During that period, the risk of occurrence of energy imbalance and maladaptation to training is high. In man, the lack of energy homeostasis is considered as the basic problem in the development of chronic fatigue. Objective: To find objective biomarkers of early maladaptation to training in young racehorses under field conditions. Methods: Sixty-five 2-year-old Standardbreds were followed during their first 3 months of training in 5 different training centres. ...
A pilot study on factors influencing the career of Dutch sport horses.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 28-32 doi: 10.1111/j.2042-3306.2010.00251.x
Sloet van Oldruitenborgh-Oosterbaan MM, Genzel W, van Weeren PR.Welfare concerns over the reasons for interruption or termination of a sporting career in horses have been expressed. Objective: To study the career of competition horses and factors that influence career length. Methods: In 2004, 46,576 rider-horse combinations were registered with the Dutch National Equestrian Federation (KNHS) in dressage, show jumping, eventing and endurance. From this population, approximately 1% of horses in each discipline were selected at random and all recorded competition data from the KNHS registration system collected and supplemented by detailed rider/owner teleph...
Muscular microRNA expressions in healthy and myopathic horses suffering from polysaccharide storage myopathy or recurrent exertional rhabdomyolysis.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 303-310 doi: 10.1111/j.2042-3306.2010.00267.x
Barrey E, Bonnamy B, Barrey EJ, Mata X, Chaffaux S, Guerin G.MicroRNAs (miRNA) are small endogenous noncoding interfering RNA molecules (18-25 nucleotides) regarded as major regulators in eukaryotic gene expression. They play a role in developmental timing, cellular differentiation, signalling and apoptosis pathways. Because of the central function of miRNAs in the proliferation and differentiation of the myoblasts demonstrated in mouse and man, it is assumed that they could be present in equine muscles and their expression profile may be related to the muscle status. Objective: To identify miRNA candidates in the muscles of control and affected horses ...
Circulating angiotensin converting enzyme in endurance horses: effect of exercise on blood levels and its value in predicting performance.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 152-154 doi: 10.1111/j.2042-3306.2010.00171.x
De Mello Costa MF, Anderson GA, Davies HM, El-Hage CM, Slocombe RF.Investigate angiotensin converting enzyme (ACE) activity in equine plasma as a predictor of performance in endurance competitions and the effect of endurance exercise on ACE activity. Objective: Precompetition values of ACE activity in equine blood are correlated with performance results and with heart rates pre- and post competition used as indicators of fitness. Endurance exercise increases ACE activity. Methods: Nineteen horses participating in an 80 km endurance competition had venous blood samples collected before and after the ride. ACE activity and total protein were measured in the blo...