Exercise in horses encompasses the physical activities that horses engage in, either through natural behaviors or structured training programs. These activities impact a horse's musculoskeletal, cardiovascular, and respiratory systems, influencing overall health and performance. Exercise can vary in intensity, duration, and frequency, and its effects are studied to understand conditioning, endurance, and recovery processes in equines. Research in this field often focuses on the physiological adaptations to different types of exercise, the prevention of exercise-related injuries, and the optimization of training regimens for various equestrian disciplines. This page compiles peer-reviewed research studies and scholarly articles that explore the physiological, biomechanical, and health-related aspects of exercise in horses.
Gerring EL.EXAMINATION of a horses 'wind' has long been a requirement at the time of sale. More recently the respiratory system has been the subject of investigation in the assessment of poor performance, although an examination for these purposes must be pan of a full clinical examination with special attention paid to the respiratory and cardiovascular systems. The differential diagnosis of adventitious respiratory sounds heard at exercise is considered here.
Ratzlaff MH, Shindell RM, DeBowes RM.Blood pressures from the catheterized lateral digital vein of the fore-limbs of 6 clinically normal horses were measured at rest, at the walk, and at the trot. Digital venous pressures were compared with the phases of the stride and weight-bearing forces, using electrogoniometry and a force platform. Rapid increases in digital venous pressures to maximal values were observed immediately before maximal forces during the support period of the stride. At the trot, increases in peak vertical forces were paralleled by increases in peak digital venous pressures. Seemingly, the hydrodynamics of the d...
Patterson PH, Coon CN, Hughes IM.Eighteen mature horses were used to study proteins requirements of working horses. Treatments included intense exercise, medium exercise and maintenance in a 3 X 3 factorial arrangement with three levels of calculated dietary crude protein (CP; 8.5, 7.0 and 5.5%). The horses were on the various exercise-protein treatments for 60 d, then fasted 4 d to evaluate their N status after the treatment period. Exercise had no significant effect on body weight over the feeding and fasting periods. No one exercise or protein treatment expressed the classical low plasma albumin or total protein concentrat...
Hodgson DR, Rose RJ, DiMauro J, Allen JR.The effects of training on skeletal muscle composition were studied in four Standardbred geldings given a seven week submaximal treadmill training programme. Before the start of training, muscle biopsies were collected from the left middle gluteal muscle for the determination of muscle fibre types, oxidative capacity and capillary numbers using histochemical techniques. The concentrations of citrate synthase, 3-hydroxyacyl-CoA dehydrogenase (HAD), lactate dehydrogenase and total muscle glycogen were measured using fluorometric methods. Muscle biopsy samples were repeated after one, three, five...
Parks CM, Manohar M.In recent years, increasing attention has been focused on the physiological responses of the horse to maximal exercise. Cardiovascular response in near maximally exercised galloping ponies (heart rate 225 +/- 7 beats/min; whole body oxygen consumption 122 +/- 12 ml/min/kg) comprised a marked increase in blood flow to the cerebellum, myocardium, diaphragm and the working muscles, while renal blood flow decreased precipitously. Cerebral and brainstem perfusion did not vary from resting values. Transmural homogeneity of myocardial blood flow persisted during near maximal exercise. It was reported...
Wyn-Jones G, Peremans KY, May SA.The management of a case of quadrilateral flexural contracture in a 10-year-old pony is described. The animal was restored to normal appearance and function through a combination of surgical desmotomy and management techniques; the importance of analgesia and exercise as adjuncts to surgery is emphasised. The aetiology and pathogenesis of the condition in the immature animal and the adult is compared and a possible association is made between this condition and palmar fibromatosis (Dupuytren's contracture) occurring in man.
Snow DH, Harris RC, Gash SP.Four thoroughbred horses performed 4 gallops (G1-G4) with intervals of 5 min. With one exception, gallops were sustained at maximal speed over 620 m. Muscle biopsy samples of the middle gluteal and brachiocephalicus were taken before, during, and after exercise and assayed for ATP and intermediary metabolites. The results showed a major involvement of the brachiocephalicus, in addition to the middle gluteal, during galloping. In three horses, who were clearly fatigued, muscle ATP decreased by up to 50% by the end of G4. This was matched by an equal rise in inosine 5'-monophosphate. Pronounced ...
Hodgson DR, Rose RJ, Allen JR, Dimauro J.Muscle biopsy samples were collected from the left middle gluteal muscle of the horses participating in day 2 (speed and endurance test) of a three day event. Six Thoroughbred horses were biopsied the day before and within 30 minutes of completion of the speed and endurance test. Serial muscle sections were reacted histochemically for myosin adenosine triphosphatase activity after acid pre-incubation to demonstrate Type I, IIA and IIB fibers and the glycogen content in the individual fibers was assessed using the periodic acid Schiff (PAS) reaction. Total glycogen in muscle was measured fluoro...
Soma LR, Laster L, Oppenlander F, Barr-Alderfer V.In 3 groups of horses with exercise-induced pulmonary hemorrhage (EIPH), comparisons of racing times and finishing positions were made between the 5 races before the horses were given furosemide and 5 races after furosemide administration. The horses were grouped according to 3 methods used to diagnose EIPH: group 1, observation of hemorrhage at the nostrils within 1 hour after a workout or race; group 2, observation of pulmonary hemorrhage only by endoscopic examination after a race or workout; and group 3, observation of hemorrhage at the nostrils during a race or immediately after a race. G...
Craig L, Hintz HF, Soderholm LV, Shaw KL, Schryver HF.There have been several studies of biochemical changes in horses doing intense exercise such as Thoroughbred and Standardbred racehorses and in horses performing exercise over a long period of time such as endurance horses and three-day eventing horses, but we are not aware of studies with polo horses. Blood samples were taken from 18 polo horses at rest, immediately after playing 2 chukkers of indoor polo, and after a 15 minute rest period. Each horse was studied at 2 different games. The blood samples were analyzed for lactic acid, protein, sodium, potassium, chloride, calcium, phosphorus, H...
Markel MD, Richardson DW.In a retrospective study, we examined the case records for 69 horses with noncomminuted fractures of the proximal phalanx, excluding proximal chip fractures. Forty-nine of the horses sustained the fracture while racing or training for racing. Radiographic examination of all affected limbs was performed, and fractures were classified into 6 noncomminuted types: midsagittal fractures, including short incomplete midsagittal fractures, long incomplete midsagittal (LIMS) fractures, and complete midsagittal (CMS) fractures; dorsal frontal fractures; distal joint fractures; plantar process fractures;...
Debski B.Erythrocytes, due to their simple metabolic processes, differ greatly from nucleated
cells. Their main metabolite of glycolysis is 2,3-Diphosphoglycerate (2,3-DPG), which
serves also as an energy store for producing ATP in the pyruvate kinase reaction. 2,3-DPG
modifies also the affinity of haemoglobin for oxygen (4). Increase in the concentration of
2,3-DPG, ATP and body temperature, or a decrease in the pH value of blood causes
decreased affinity of haemoglobin for oxygen as blood transverses muscle capillaries,
facilitating oxygen delivery. In equine erythrocytes, the level of ATP is s...
Burrell MH.A group of racehorses in training was examined on several occasions with a fibreoptic endoscope and monitored for viral infection. Only equine herpes virus-2 (EHV-2) infection was detected. Pharyngeal lymphoid hyperplasia (PLH) was present in all horses and decreased in severity with age. There was no association between PLH severity and antibody titres to EHV-1, or with the isolation of EHV-2. Finishing position in races was not affected by PLH severity. Exercise induced pulmonary haemorrhage (EIPH) was evident on 23 out of 49 (47 per cent) examinations after maximal speed training exercise. ...
Saibene F, Cortili G, Gavazzi P, Sala A, Faina M, Sardella F.Blood lactate concentrations were determined in 16 horses (three Thoroughbreds, seven Standardbreds and six polo ponies) before and 5 mins after they galloped over distances of 200, 300 and 400 m at maximal speed. The highest net lactate concentration (delta Lamax) of 14 to 15 mmol/litre was attained by the polo ponies and the highest speed by the Thoroughbreds. The maximal rate of lactate production (delta Låmax) was about 35 mmol/litre X min for the polo ponies and 20 to 25 mmol/litre X min for the Standardbreds and the Thoroughbreds. Values for delta Lamax and delta Låmax were similar to ...
Taylor CR.This paper develops three simple ideas about force development during sustained locomotion which provide some insights into the mechanisms that determine why animals change gait, how fast they can run, and how much metabolic energy they consume. The first idea is that the alternate stretch-shorten pattern of activity of the muscles involved in locomotion allows muscle-tendon units to function as springs, affecting the amount of force a given cross-sectional area of muscle develops, and the metabolic requirements of the muscles for force development. Animals select speeds and stride frequencies...
McMahon TA.The running gaits used by both bipedal and quadrupedal animals are reviewed and contrasted. At high speeds, bipeds use both ordinary running, in which the legs move opposite one another, and hopping. Quadrupeds generally use the trot or its variations at moderate speeds, and first the canter and then the gallop as speed increases. Running in both bipeds and quadrupeds generally involves at least one aerial phase per stride cycle, but certain perturbations to running including running in circles, running under enhanced gravity, running on compliant surfaces and running with increased knee flexi...
Uehara N, Sawazaki H, Mochizuki K.The area of the largest transverse section and the number of muscle fibres in a unit sectional area (1 mm2) were examined in 8 trunk and 12 extremity muscles of young and adult 16 light horses and 8 ponies. It was found that the area of the largest transverse section was enlarged and the number of muscle fibres in a unit area was decreased, with the advance in age. This result suggests that the development of muscle volume does not depend on the increase in the number of fibres, but depends on the hypertrophy of each muscle fibre.
Rossdale PD, Hopes R, Digby NJ, offord K.An epidemiological study of wastage among racehorses was conducted in 1982 and 1983 among six stables, five of which were in Newmarket. The basis of the survey was the inability of horses to take part in cantering exercise as a result of injury or disease. The greatest number of days lost to training was caused by lameness (67.6 per cent) and respiratory problems (20.5 per cent). Conditions of the foot (19 pe cent), muscle (18 per cent), carpus (14 per cent), fetlock joints (14 per cent), tendons (10 per cent) and sore shins (9 per cent) were the major reasons for training days being lost in 1...
Kociba GJ, Bayly WM, Milne DW, Wigton DH, Gabel AA, Muir WW.Two groups of 6 Standardbred horses each were used to study hemostatic functions at rest and after exercise with furosemide or a placebo. One group which was trained was given maximum exercise on the racetrack, and the other, a less-fit group, was given submaximum exercise on the treadmill. There was no difference in furosemide compared to placebo trial results in either group in coagulation screening tests, platelet concentration, or retention of platelets in a glass bead column. Increased fibrinogen concentration and enhanced platelet retention were associated with maximum exercise. Aggregat...
Forster HV, Pan LG, Bisgard GE, Flynn C, Dorsey SM, Britton MS.The objective of this study was to determine whether changes in limb motion per se influence arterial CO2 partial pressure (PaCO2) during muscular exercise in ponies. Fifteen ponies were studied at rest and during 8 min of treadmill exercise when the work load was constant or when the work load was increased after the 4th min. Five different treadmill settings were selected to provide for a range of metabolic rate achieved with primary changes in either speed or grade (1.8 mph at 3, 8, and 15% grade; or 3 and 6 mph at 3% grade). The ponies exercised either on all four legs or on only the hindl...
Crawford WH, Leach DH.A survey of a western Canadian racetrack determined the superelevation and transition curves to be less than the cited design standards. High-speed cinematography was used to film seven Standardbred pacers as they proceeded around one curve of the track at racing speed and for each horse 19 temporal stride parameters were obtained from these films using a film analyzer system. Average velocities were calculated and the mean stride length was found to vary from 5.08 m to 5.77 m. In all frames analyzed the hind foot was observed to contact the track surface prior to the ipsilateral forefoot and ...
Bayly WM, Grant BD, Breeze RG.Arterial blood gas and acid-base values during maximal exercise over a 1.2 km distance were recorded in four Thoroughbred horses before and after the chemical induction of pharyngeal lymphoid hyperplasia (PLH). Samples were collected after galloping 0.8 km and 1.2 km, immediately upon stopping and 5 mins after exercising. In only one horse was any difference noted in the pre and post PLH induction results. The horse was more hypercapnoeic at the 1.2 km mark and also took much longer to complete the gallop when it had PLH. However, it also had signs of lower respiratory disease. In the other ho...
Pan LG, Forster HV, Bisgard GE, Dorsey SM, Busch MA.We assessed the relationship of ventilation (VE) to cardiodynamic variables and CO2 transport in seven normal ponies during treadmill exercise. At 1.8, 3, and 6 mph, respectively, VE increased from 15 l/min at rest to 43, 51, and 86 l/min by 1 min and 48, 68, and 125 l/min by 8 min. In three ponies at the same work loads, cardiac output (Qc) increased from approximately 12 l/min at rest to 19.7, 28.1, and 40.3 l/min between 30-60 s (P less than 0.05) and then decreased by about 20% to a steady state by 3-4 min. Heart rate (HR) shows a similar biphasic response during exercise. Mean right ventr...
Anderson GF, Landsheft B.Performance horses should be thoroughly examined before sale to detect any defects that could render them unsuitable for the purchaser's intended use. With the horse in its stall, the eyes, nasolacrimal puncta, external ear canals and mouth are examined, the rectal temperature measured and the heart, lungs, trachea and sinuses auscultated. Moving the horse out of the stall, the head, parotid glands, mandibular lymph nodes, larynx, neck muscles, jugular veins and cervical vertebrae are inspected. The scapula, point of the shoulder, withers, tuber sacrale and point of the hip are palpated, after...
Forster HV, Pan LG, Bisgard GE, Dorsey SM, Britton MS.We characterized the temporal patterns of pulmonary O2 consumption (VO2) and CO2 excretion (VCO2) in exercising ponies. We also assessed the cardiac, ventilatory, and hematologic contributions to the VO2-VCO2 changes during exercise. At five moderate treadmill work loads in normal ponies, VO2 and VCO2 generally increased progressively throughout the 1st min reaching, respectively, approximately 95 and 80% of steady state by 45-60 s. Between 1 and 1.5 min, Vo2 and Vco2 were either stable or they decreased 300-500 ml, but then each increased slightly, reaching steady-state levels between 3 and 5...
Pan LG, Forster HV, Bisgard GE, Dorsey SM, Busch MA.We assessed cardiovascular variables and blood O2 contents in order to characterize O2 transport in ponies during treadmill exercise. In normal ponies at 1.8, 3, and 6 mph, respectively, cardiac output (Qc) increased from 12 l/min at rest to maximum levels of 19.7, 28.7, and 39.9 l/min between 30 and 60 s. Qc then decreased to steady-state levels of 18.2, 24.6, and 32.7 l/min by 4 min. Heart rate (HR) showed a similar biphasic response in the 1st min of exercise. Systolic and diastolic arterial blood pressure (BP) decreased at the onset of exercise by 20-25 Torr (P less than 0.05) and then inc...
Sandin A, Girma K, Sjöholm B, Lindholm A, Nilsson G.Plasma gastrin concentrations were determined in 6 Standardbreds (4 geldings and 2 mares) after 3 different meals consisting of unlimited amounts of hay (8-9 kg per horse), a restricted amount of hay (0.6 kg/100 kg body-weight) and grain (0.2 kg/100 kg body-weight) in combination or of grain alone (0.2 kg/100 kg body-weight). In another series of experiments the possible role of gastrin as a stress hormone was investigated. Plasma gastrin and cortisol concentrations were determined during fasting and compared with concentrations during hay feeding. In addition, gastrin and cortisol concentrati...
Butcher MT, Bertram JE, Syme DA, Hermanson JW, Chase PB.The digital flexors of horses must produce high force to support the body weight during running, and a need for these muscles to generate power is likely limited during locomotion over level ground. Measurements of power output from horse muscle fibers close to physiological temperatures, and when cyclic strain is imposed, will help to better understand the in vivo performance of the muscles as power absorbers and generators. Skinned fibers from the deep (DDF) and superficial (SDF) digital flexors, and the soleus (SOL) underwent sinusoidal oscillations in length over a range of frequencies (0....
Foreman JH.Metabolic causes of exercise intolerance can be subtle and difficult to document in horses. Because of increased metabolic rate in exercising muscle, most metabolic causes of exercise intolerance are clinically manifested by muscle abnormalities such as ER. Newer causes of ER are being documented by current research and are summarized in the article on muscular causes of equine exercise intolerance. Endocrine causes of exercise intolerance have been poorly documented, but recent work has shown the detrimental effects of hypothyroidism on exercise tolerance in horses. Many metabolic manifestati...
Manohar M, Goetz TE, Nganwa D.Diaphragmatic O2 and lactate extraction were examined in seven healthy ponies during maximal exercise (ME) carried out without, as well as with, inspiratory resistive breathing. Arterial and diaphragmatic venous blood were sampled simultaneously at rest and at 30-s intervals during the 4 min of ME. Experiments were carried out before and after left laryngeal hemiplegia (LH) was produced. During ME, normal ponies exhibited hypocapnia, hemoconcentration, and a decrease in arterial PO2 (PaO2) with insignificant change in O2 saturation. In LH ponies, PaO2 and O2 saturation decreased well below tha...
Baillet H, Leroy D, Vérin E, Delpouve C, Boulanger J, Benguigui N, Komar J, Thouvarecq R.The present research aims at quantifying the impact of practicing a new coordination pattern with an online visual feedback on the postural coordination performed on a mechanical horse. Forty-four voluntary participants were recruited in this study. They were randomly assigned to four practice groups based on i) with or without feedback (i.e., group 1, control, did not receive the feedback; group 2, 3 and 4 received an online feedback during practice) and ii) the specific trunk/horse coordination to target during practice (group 1, target coordination = 180° (without feedback); group 2, targe...
Ingvast-Larsson C, Kallings P, Persson S, Appelgren LE, Wiese B.The pharmacokinetics of theophylline at rest and the effects on cardio-respiratory and blood lactate responses to exercise were investigated after repeated oral administrations in six healthy Standardbred horses. A dose of 5 mg/kg body weight was administered every 12 h. The binding of theophylline to plasma protein was also determined. There was good agreement between predicted and observed plasma concentrations of theophylline at steady state. The mean half-life of elimination was shown to be 17.0 +/- 2.5 h, the mean half life of absorption was 1.6 +/- 1.8 h, the apparent volume of distribut...
Pruett HE, Thompson DL, Cartmill JA, Williams CC, Gentry LR.Light horse mares, stallions, and geldings were used to 1) extend our observations on the thyrotropin releasing hormone (TRH) inhibition of GH secretion in response to physiologic stimuli and 2) test the hypothesis that stimulation of endogenous TRH would decrease the normal rate of GH secretion. In Exp. 1 and 2, pretreatment of mares with TRH (10 microg/kg BW) decreased (P < 0.001) the GH response to exercise and aspartate infusion. Time analysis in Exp. 3 indicated that the TRH inhibition lasted at least 60 min but was absent by 120 min. Administration of a single injection of TRH to stal...
Kirberger RM, Gottschalk RD, Guthrie AJ.Twelve horses were injected intra-articularly into the metacarpophalangeal joint and extra-articularly in the region of the lateral palmar digital nerve with 1 ml air and local anaesthetic to simulate gas accidentally introduced during regional anaesthesia. Half the horses underwent limited exercise after which all horses were radiographed at 15 and 45 min and then every 24 h until all evidence of gas had disappeared. Intra-articular gas appeared as gas capped radiolucencies (GCR) in the proximal aspect of the joint. Extra-articular gas appeared as linear radiolucencies (LR) which initially te...
Nardelli M, Lanata A, Valenza G, Sgorbini M, Baragli P, Scilingo EP.This paper reports on a novel real time index designed to assess the quality of electrocardiographic (ECG) traces recorded in a group of five horses during a submaximal treadmill test procedure. During the experimental protocol two ECG monitoring systems were simultaneously applied to the animals. The first system was equipped with textile electrodes while the second one with standard red-dot electrodes. The procedure comprised four phases with an increased treadmill velocity, specifically, Walk 1, Trot 1, Trot 2 and Gallop. Three signal quality levels have been fixed according to the amount o...
Eto D, Yamano S, Hiraga A, Miyata H.There is little information about the muscle fibre recruitment pattern during sloped and flat track running in Thoroughbred horses. Objective: To examine the glycogen depletion pattern of each muscle fibre type during running on a flat and sloped treadmill. Methods: Thirteen Thoroughbred horses (3-9 years old) were used. They were initially subjected to incremental exercise tests on a treadmill at 10 and 0% inclines in each horse to determine running speed at 90 and 60% VO2max. Needle biopsy samples were obtained from the middle gluteal muscle immediately after the running at 90% VO2max for 4 ...
Kaikkonen M, Hyyppä S.Like potassium (K+), caesium (Cs+) tends to concentrate intracellularly. The aim here was to determine how moderate exercise affects the uptake of Cs+ from blood plasma. Methods: After an intravenous Cs+ dose of 5 micromol kg(-1), plasma Cs+ concentration was followed for 100 min in goats and for 60 min in horses. The latter were divided into two groups, one resting and the other trotting on a treadmill (inclination 3 degrees, speed 5 m s(-1)). Results: The plasma Cs+ concentration follows a multiphase exponential decay curve, which initially could be approximated with a two-phase curve. The i...
Caltabilota TJ, Milizio JG, Malone S, Kenney JD, McKeever KH.The purpose of this study was to test the hypothesis that sucralfate, a gastric ulcer medication, would alter plasma concentrations of total carbon dioxide (tCO2), lactate (LA), sodium (Na+), potassium (K+), chloride (Cl-) and total protein (TP), as well as calculated plasma strong ion difference (SID) and packed cell volume (PCV) in horses subjected to a simulated race test (SRT). Six unfit Standardbred mares (approximately 520 kg, 9-18 years) were used in a randomized crossover design with the investigators blinded to the treatment given. The horses were assigned to either a control (40-50 m...
Fenton JI, Orth MW, Chlebek-Brown KA, Nielsen BD, Corn CD, Waite KS, Caron JP.The effect of longeing and glucosamine supplementation on known biological markers of joint disease was studied in yearling quarter horses. Twenty-one yearling quarter horses were randomly assigned to one of 4 treatments: 1) longeing (longeing 20 min daily) supplement control (LN); 2) longeing/glucosamine (LG); 3) walking (mechanical walker for 120 min daily (WN)); and 4) walking/glucosamine (WG). Oral glucosamine was administered at 5.5 g b.i.d. weeks 1-4, 3.5 g b.i.d. during weeks 5-6, and 2.0 g b.i.d. during weeks 7-8. Serum was obtained weekly for 8 wk and analyzed for keratan sulfate and ...
Buzzetti AP, Nothaft IT, Paganela JC, Franzan BC, Braga GI, Barreira APB, de Lima LR, de Almeida FQ.This study aimed to perform ultrasonographic evaluation of the digital flexor tendons of jumping horses undergoing complementary training on a treadmill. Fifteen Brazilian Sport horses were divided into two groups: Group I with 7 animals in physical training complementary to the standard training at the Brazilian Army's Riding School; and Group II with 8 animals in standard training used in the Brazilian Army's Riding School. Complementary training was performed on a treadmill on an inclined plane. Ultrasonographic images were taken at the beginning and at the end of training. The left thoraci...
Anderson GF, Landsheft B.Performance horses should be thoroughly examined before sale to detect any defects that could render them unsuitable for the purchaser's intended use. With the horse in its stall, the eyes, nasolacrimal puncta, external ear canals and mouth are examined, the rectal temperature measured and the heart, lungs, trachea and sinuses auscultated. Moving the horse out of the stall, the head, parotid glands, mandibular lymph nodes, larynx, neck muscles, jugular veins and cervical vertebrae are inspected. The scapula, point of the shoulder, withers, tuber sacrale and point of the hip are palpated, after...
Harmegnies NF, Duvivier DH, Vandenput SN, Art T, Lekeux PM, Votion DM.This study aimed to compare exercise-induced pulmonary perfusion redistribution in healthy vs. 'heavey' horses using scintigraphy, a minimally invasive technique. Six healthy (A) and 5 'heavey' horses in remission (B(I)) and during clinical signs of disease (B(II)) were investigated. Dimensions of the exercising pulmonary perfusion (QE) images were expressed in percent of the resting perfusion (QR) images. Computed QE to QR ratios (QE/QR) images enabled the definition of the region more perfused at exercise than at rest (R1). In all groups, exercise induced a major enlargement of the Q image b...
Frape DL.There is no clear evidence that the chronic requirement for any non-energy yielding nutrient rises in proportion as the energy requirement increases with hard work. The need for protein, and probably that for calcium, remain a function of bodyweight daily. Some proportionality with energy may exist for certain nutrients, although the evidence has not been adduced. For example, because of an increase in both the proportion and amount of propionic acid in the volatile fatty acids of caecal contents, the tissue requirement for vitamin B12 may rise with an increase in the rate of energy metabolism...
Hinchcliff KW, McKeever KH, Muir WW.The systemic haemodynamic and acid-base effects of the administration of phenylbutazone (4.4 mg kg-1 intravenously) to standing and running horses were investigated. Phenylbutazone, or a placebo, was administered to each of six mares either 15 minutes before, or after 30 minutes of a 60-minute submaximal exercise test which elicited heart rates approximately 55 per cent of maximal, and to the same horses at rest. The variables examined included the cardiac output, heart rate, systemic and pulmonary arterial pressures, right atrial and right ventricular pressures, and arterial and mixed venous ...
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...
Gehlen H, Bubeck K, Stadler P.In 12 healthy warmblood horses (six trained and six untrained) the pulmonary wedge pressure and heart frequency was measured at rest and during a standardised exercise test on a treadmill. The mean pulmonary wedge pressure at rest was 14.53 +/- 2.36 mmHg. There was no significant difference in pulmonary wedge pressure either at rest or during exercise between trained and untrained horses. During walking (1.8 m/s) the mean pulmonary wedge pressure was 19.62 +/- 4.03 mmHg, during trotting (4 und 5 m/s) it was between 22.38 +/- 3.92 mmHg and 25.28 +/- 3.7 mmHg. During canter (6 m/s) and gallop (8...
Peloso JG, Stick JA, Nickels FA, Lumsden JM, Derksen FJ.A 2-year-old 400-kg Standardbred colt with a history of exercise intolerance was determined to have dorsal displacement of the soft palate (DDSP). Standing endoscopy revealed a soft, flaccid, and hypoplastic epiglottis and arytenoid cartilages that moved symmetrically and abducted fully. Lateral laryngeal radiography was used to calculate a corrected thyroepiglottic length of 6.48 cm. Videoendoscopy during exercise on a high-speed treadmill at standardized treadmill speeds was performed weekly for 3 consecutive weeks. The soft palate dorsally displaced at each examination. A sternohyoideus/ste...
McKeever KH.This article has presented information on the importance of the sympathetic nervous system in the response to exercise. The authors have reviewed the very limited information on the effects of sympathomimetic and sympatholytic drugs on exercise performance in the horse. Most of these drugs are specifically prohibited under the rules of racing, and they have significant side effects that either decrease performance or make their use dangerous to both the horse and horse-man. Additionally, all of these drugs or their metabolites are readily detected by current drug testing protocols. Further inf...
Bailey J, Redpath A, Hallowell G, Bowen M.The clinical examination of lame horses in real world settings often requires the use of sloped surfaces. This pilot study aimed to evaluate the effects of uphill and downhill locomotion on asymmetry in horses with naturally occurring lameness affecting forelimbs and hindlimbs. Ten horses (8-19 years) with forelimb lameness and eight horses (7-16 years) with hindlimb lameness were fitted with inertial sensors at the poll, withers, sacrum and both tuber coxae. Data were collected whilst the horses were trotted in hand on a level surface (20 mm) among conditions in individual horses. Two horse...
Bain FT, Merritt AM.To investigate the possibility that a disorder of potassium balance may have a role in the development of equine rhabdomyolysis, the potassium concentration within erythrocytes (RBC [K+]) and plasma (P [K+]) was measured in 3 groups of horses: group 1, eight 2-year-old fillies that had postexercise muscle soreness within 48 hours of sample collection; group 2, ten 2-year-old fillies subjected to identical management and training conditions (as fillies of group 1) and that did not have signs of myopathy; and group 3, 32 yearlings of both sexes on the farm of origin of groups 1 and 2 that were p...
Hartley JW, Hahn AW, DeLorey M, Caldwell WM.We have developed and used a system for recording and analyzing the electrocardiogram (ECG) of the horse during exercise. The system consists of a commercial ECG transmitter telemetering a Z lead (base-apex) ECG from an exercising horse. The received data are then remodulated at an audio frequency and stored on a audio cassette recorder. Exercise protocols of up to 10 minutes are digitized using a Macintosh II computer. For rhythm analysis, a computer program to identify the various waves of the ECG uses a modification and refinement of the integrated-squared-derivative (ISD) technique. This t...
Jiang B, Rugh KS, Hatfield DG, Jiang D, Hahn AW.We have developed a digital signal analysis technique which can be used to evaluate various cardiac events in ponies and horses at rest and during exercise. The algorithm is designed to identify R-wave peaks on the surface electrocardiogram, consistent reference points on the left ventricular pressure waveform and the initiation of the QRS complex on the epicardial electrogram. We have used the technique to evaluate data from 10 horses and ponies at rest, during strenuous exercise and during experimentally-induced coronary artery occlusion. The technique provided rapid and accurate beat-by-bea...
Knight PK, Ray SP, Rose RJ.Because the haemoglobin concentration Hb[ during exercise may be at the upper limit of blood viscosity for effective oxygen delivery, we hypothesised that administration of blood would not further enhance oxygen delivery or exercise capacity. Six Thoroughbred geldings were used in 5 incremental treadmill exercise tests over a period of 4 weeks. The first test was performed 6 days prior to phlebotomy, which involved the removal of 20 ml/kg bwt of venous blood. Exercise tests were performed at 1, 8 and 15 days after blood removal. Six days after the 15 day post phlebotomy exercise test, blood fr...
Shearman JP, Hopkins WG.To evaluate the reliability of 2 time-trial protocols, 1 that involved use of a pacemaker and 1 that did not, for assessing performance of Standardbred racehorses. Methods: 3- to 7-year-old Standardbred maiden pacers. Methods: 11 Standardbred pacers were used to determine the reliability of a time-trial protocol that involved use of a galloping pacemaker. All tests were performed by a single driver. Horses were paced for an initial 1,600 m then raced and timed for the final 800 m. They were retested 9 days later. Twenty-two horses were used to determine the reliability of a time-trial protocol...
van den Belt AJ, Becker CK, Dik KJ.The clinical and ultrasonographic features of desmitis of the accessory ligament of the deep digital flexor tendon (carpal check ligament) are reported in a series of 24 horses. Lameness associated with the carpal check ligament especially was found in Warmblood riding horses ranging in age from 6 to 18 years with a mean age of 11.3 years. The most striking clinical feature was a firm, painful swelling medially and laterally in the proximal and/or mid metacarpal region, corresponding with the dorsoproximal-palmarodistal oblique direction of the carpal check ligament. Sonographically swelling o...
Smetzer DL, Senta T, Hensel JD.Each of nine horses was treated with amphetamine alone, with atropine alone, and with amphetamine and atropine in combination. Cardiac effects of these drugs were studied by electrocardiography during resting and exercising states and immediately after exercise. Although each treatment increased heart rate significantly during the resting state, only the amphetamine plus atropine treatment increased heart rate significantly during exercise. Decrease in heart rate immediately after exercise differed significantly for each treatment; the most rapid decrease in heart rate was found after the amph...
