Heart rate in horses is a physiological parameter that reflects the number of heartbeats per minute. It is an important indicator of cardiovascular function and can be influenced by factors such as exercise, stress, excitement, and health status. Monitoring heart rate provides valuable insights into the horse's physical condition and can aid in assessing fitness levels or detecting potential health issues. In equine practice, heart rate is often measured using stethoscopes, heart rate monitors, or electrocardiograms. This page compiles peer-reviewed research studies and scholarly articles that explore the determinants, measurement techniques, and implications of heart rate variations in equine health and performance.
Decloedt A, De Clercq D, Ven Sofie S, Van Der Vekens N, Sys S, Broux B, van Loon G.Right ventricular (RV) function is scarcely described in horses. Objective: To establish reliable echocardiographic measurements of right heart size and function in horses. Methods: Descriptive study in healthy horses. Methods: Ten healthy untrained adult trotter horses underwent repeated echocardiography performed by 2 sonographers from right and left parasternal standard and nonstandard views. Nonstandard views included a right parasternal view focused on the right atrium, left parasternal long-axis pulmonary artery view, left parasternal long-axis view focused on the right ventricle includi...
Smith AV, Proops L, Grounds K, Wathan J, McComb K.Whether non-human animals can recognize human signals, including emotions, has both scientific and applied importance, and is particularly relevant for domesticated species. This study presents the first evidence of horses' abilities to spontaneously discriminate between positive (happy) and negative (angry) human facial expressions in photographs. Our results showed that the angry faces induced responses indicative of a functional understanding of the stimuli: horses displayed a left-gaze bias (a lateralization generally associated with stimuli perceived as negative) and a quicker increase in...
Rigby BR, Grandjean PW.To summarize the physical benefits of therapeutic horseback riding and hippotherapy and suggest directions for future research. Methods: Review of databases for peer-reviewed articles related to equine-assisted activities and therapies. Databases included MEDLINE via EBSCO, Web of Science, PubMed, Google Scholar, and Academic Search Complete. Articles were limited to those with full-text access published in English since 1987. Results: Acute and residual improvements in physical benefits, such as gross motor function (e.g., walking, running, jumping), spasticity, muscle symmetry, posture, bala...
Firshman AM, Borgia LA, Valberg SJ.To compare effects of training on conventional and underwater treadmills on fiber properties and metabolic responses of the superficial digital flexor (SDF) and gluteal muscles to high-speed exercise in horses. Methods: 6 unconditioned Quarter Horse-type horses. Methods: 6 horses were walked on underwater and conventional treadmills for 5 d/wk (maximum, 40 min/d) for 8 weeks in a randomized crossover design (60-day detraining period). Horses underwent a standardized exercise test (SET) at high speed before and after training. Analyte concentrations and fiber characteristics were measured in mu...
Teixeira FA, Araújo AL, Ramalho LO, Adamkosky MS, Lacerda TF, Coelho CS.The aim of this study was to evaluate the effects of oral creatine supplementation on the athletic performance of equines used for barrel racing. Ten healthy Quarter Horses, or Quarter Horse crossbred, weighing 429.7 ± 25.3 kg and with mean age of 3.8 ± 1.2 years, were used. Animals were evaluated in four different moments (M1, M2, M3, M4), and between M3 and M4, they were supplemented with 28 g of creatine/100 kg of body weight, orally, for 45 days. Although significant alterations for LDH activity, plasma glucose and packed cell volume were observed, it was possible to conclude th...
Conde Ruiz C, Cruz Benedetti IC, Guillebert I, Portier KG.This prospective blinded randomized study aimed to determine whether the timing of morphine and phenylbutazone administration affects the breathing response to skin incision, recovery quality, behavior, and cardiorespiratory variables in horses undergoing fetlock arthroscopy. Ten Standardbred horses were premedicated with acepromazine (0.04 mg kg(-1) IM) and romifidine (0.04 mg kg(-1) IV). Anesthesia was induced with diazepam (0.05 mg kg(-1)) and ketamine (2.2 mg kg(-1)) IV at T0. Horses in group PRE (n = 5) received morphine (0.1 mg kg(-1)) and phenylbutazone (2.2 mg kg(-1)) I...
Schrammel N, Deichsel K, Aurich J, Aurich C.Horses are seasonal breeders, and robust breeds may exhibit a winter hypometabolism when kept under semiferal conditions. In this study, we analyzed the effects of artificial long days on rectal temperature, heart rate, heart rate variability, hematology, coat changes, semen parameters, and plasma testosterone concentrations in Shetland stallions stabled overnight and assigned to a control group (CON, n = 9) kept under natural photoperiod, and a treatment group exposed to a long-day light program from 15 December to 20 March (AL, n = 9). During the 8-month study, rectal temperature, heart rate...
Kusano K, Nomura M, Toju K, Ishikawa Y, Minamijima Y, Yamashita S, Nagata S.Procaterol (PCR) is a beta-2-adrenergic bronchodilator widely used in Japanese racehorses for treating lower respiratory disease. The pharmacokinetics of PCR following single intravenous (0.5 μg/kg) and oral (2.0 μg/kg) administrations were investigated in six thoroughbred horses. Plasma and urine concentrations of PCR were measured using liquid chromatography-mass spectrometry. Plasma PCR concentration following intravenous administration showed a biphasic elimination pattern. The systemic clearance was 0.47 ± 0.16 L/h/kg, the steady-state volume of the distribution was 1.21 ± 0.23 L/kg, ...
Potter JJ, MacFarlane PD, Love EJ, Tremaine H, Taylor PM, Murrell JC.To compare sedative and analgesic properties of buprenorphine or morphine for standing procedures combined with a detomidine continuous rate infusion (CRI). Methods: Blinded, prospective, randomized clinical pilot study. Methods: Ten horses presented for dental or sinus procedures. Methods: Horses received 0.02 mg kg(-1) acepromazine intravenously (IV), followed 30 minutes later by detomidine 10 μg kg(-1) IV. Five minutes later, buprenorphine 0.01 mg kg(-1) (n = 6) or morphine 0.1 mg kg(-1) (n = 4) was administered IV. Detomidine was administered by CRI (0.2 μg kg(-1) minute(-1)) and adjuste...
Stefánsdóttir GJ, Ragnarsson S, Gunnarsson V, Roepstorff L, Jansson A.This study compared the effect of ridden tölt and trot at 3 speeds on physiological responses in trained adult (15.3 ± 1.6 yr) Icelandic horses. The experiment had a crossover design with 8 horses, 2 treatments (incremental exercise test in tölt and trot), and 2 riders. Each horse performed 2 tests per day (1 gait with 2 riders, minimum 4.5 h between) on 2 separate days, with 1 d of rest in between. The exercise test consisted of three 642-m phases at 3.0 m/s (Speed), 4.0 m/s (Speed), and 5.0 m/s (Speed) and was performed outdoors on a 300-m oval gravel riding track in northern Iceland in M...
Curtis L, Burford JH, Thomas JS, Curran ML, Bayes TC, England GC, Freeman SL.The majority of research on the evaluation of horses with colic is focused on referral hospital populations. Early identification of critical cases is important to optimise outcome and welfare. The aim of this prospective study was to survey the primary evaluation of horses with clinical signs of abdominal pain by veterinary practitioners, and compare the initial presentation of critical and non-critical cases. Results: Data from 1016 primary evaluations of horses presenting with clinical signs of colic were submitted by 167 veterinary practitioners across the United Kingdom over a 13 month p...
Casella S, Vazzana I, Giudice E, Fazio F, Piccione G.The changes of cortisol, red blood cells (RBC), hemoglobin (Hb), hematocrit (Hct), heart rate (HR), respiratory rate (RR) and rectal temperature (RT) were evaluated after a reining training session in eight Quarter Horses. All parameters were measured before exercise (T0), immediately after exercise (T1), 1 h after exercise (T2), 2 h after exercise (T3) and 24 h after exercise (T4). One-way analysis of variance (ANOVA) for repeated measures, followed Bonferroni's post hoc test, showed a significant effect of the reining training session (P < 0.0001) on cortisol, RBC, Hb, Hct, HR, RR and RT. Si...
Christensen JW.Fear reactions in horses are a major cause of horse-human accidents, and identification of effective pathways for reduction in fearfulness can help decreasing the frequency of accidents. For a young mammal, the mother is one of the most salient aspects of its environment, and she can have a strong influence on her offspring's behaviour. This study investigated whether fearfulness in foals can be reduced through weekly exposure to usually frightening objects with a habituated mother during the first 8 weeks of life. Prior to foaling, mares (N = 22) were habituated to five initially fear-elic...
Tavanaeimanesh H, Dezfouli MR, Vajhi A, Rostam A, Akbarinejad V, Sadeghian Chaleshtori S, Corley KT.The cardiovascular effects and duration of action of hypertonic saline are not yet fully understood in the horse. Objective: To determine the effects of hypertonic saline on cardiac measurements derived from echocardiography over a period of 90 min after infusion in euvolaemic and healthy horses. Methods: Experimental study. Methods: Five healthy conscious euvolaemic horses were infused with 5 ml/kg bwt hypertonic saline via a jugular catheter over 1 h. Immediately prior to infusion and at 0, 20, 40, 60 and 90 min after the completion of the infusion, echocardiographic images were obtained fro...
Younes M, Robert C, Cottin F, Barrey E.Nearly 50% of the horses participating in endurance events are eliminated at a veterinary examination (a vet gate). Detecting unfit horses before a health problem occurs and treatment is required is a challenge for veterinarians but is essential for improving equine welfare. We hypothesized that it would be possible to detect unfit horses earlier in the event by measuring heart rate recovery variables. Hence, the objective of the present study was to compute logistic regressions of heart rate, cardiac recovery time and average speed data recorded at the previous vet gate (n-1) and thus predict...
Villas-Boas JD, Dias DP, Trigo PI, Almeida NA, de Almeida FQ, de Medeiros MA.Startle is a fast response elicited by sudden acoustic, tactile, or visual stimuli in a variety of animals and in humans. As the magnitude of startle response can be modulated by external and internal variables, it can be a useful tool to study reaction to stress. Our study evaluated whether acupuncture can change cardiac autonomic modulation (heart rate variability); and behavioural (reactivity) and endocrine (cortisol levels) parameters in response to startle. Brazilian Sport horses (n = 6) were subjected to a model of startle in which an umbrella was abruptly opened near the horse. Before s...
Nagel C, Ille N, Erber R, Aurich C, Aurich J.Invasive procedures in animals are challenging for veterinary students who may perceive a gynaecological examination of mares as stressful. Simulator-based training may reduce stress. In this study, students received equine gynaecology training 4 times either on horses (group H; n = 14) or a teaching simulator (group SIM; n = 13). One day and 14 days thereafter, their diagnostic skills were tested on horses (skills tests 1 and 2). During the skills tests, the students' stress response was analysed by heart rate, heart rate variability (HRV) parameters SDRR (standard deviation of beat-to-b...
McConachie EL, Giguère S, Rapoport G, Barton MH.To describe heart rate variability (HRV) in horses with acute gastrointestinal disease that undergo exploratory laparotomy. We hypothesized that horses with ischemic gastrointestinal disease will have reduced HRV compared to horses with nonischemic lesions. We further hypothesized that a reduction in HRV will be associated with nonsurvival. Methods: Prospective, clinical, observational study. Methods: University veterinary teaching hospital. Methods: Horses presented for acute colic (n = 57) or elective surgical procedures (n = 10) were enrolled. Methods: Admission heart rate (HR) was recorded...
Briefer Freymond S, Bardou D, Briefer EF, Bruckmaier R, Fouché N, Fleury J, Maigrot AL, Ramseyer A, Zuberbühler K, Bachmann I.Stereotypies are repetitive and relatively invariant patterns of behavior, which are observed in a wide range of species in captivity. Stereotypic behavior occurs when environmental demands produce a physiological response that, if sustained for an extended period, exceeds the natural physiological regulatory capacity of the organism, particularly in situations that include unpredictability and uncontrollability. One hypothesis is that stereotypic behavior functions to cope with stressful environments, but the existing evidence is contradictory. To address the coping hypothesis of stereotypies...
Fortier J, Deley G, Julliand V.This study aimed at quantifying energy expenditure during 4 specific training exercises, that is, promenade, jogging, parcours, and interval exercises, using field measurements of oxygen consumption and heart rate in trotters. Six animals performed 2 preliminary tests to determine their individual maximum velocity and to establish their individual oxygen consumption/heart rate relationship from an incremental test. Then, they undertook each of the 4 specific exercises separated by 1 wk to avoid fatigue. The intensity of the 4 exercises was expressed in percent of individual maximum velocity as...
Afonso T, Giguère S, Rapoport G, Barton MH, Coleman AE.Pimobendan is an inodilator used in dogs for the management of heart failure due to myxomatous valve disease or dilated cardiomyopathy. The lack of data regarding the effects of pimobendan in horses prevents the rational use of this drug. Objective: To determine the cardiovascular effects of pimobendan in healthy mature horses. Methods: Randomised experimental study. Methods: Five horses were fasted overnight prior to receiving i.v. pimobendan (0.25 mg/kg bwt), intragastric (i.g.) pimobendan (0.25 mg/kg bwt) or i.g. placebo with a washout period of one week between each administration. Horses ...
Cullen S, OʼLoughlin G, McGoldrick A, Smyth B, May G, Warrington GD.The physiological demands of jockeys during competition remain largely unknown, thereby creating challenges when attempting to prescribe sport-specific nutrition and training guidelines. The purpose of this study was to evaluate the physiological demands and energy requirements of jockeys during flat racing. Oxygen uptake (V[Combining Dot Above]O2) and heart rate (HR) were assessed in 18 male trainee jockeys during a race simulation trial on a mechanical horse racing simulator for the typical time duration to cover a common flat race distance of 1,400 m. In addition, 8 male apprentice jockeys ...
Lemasson A, Remeuf K, Hausberger M.Animal calls are commonly considered indicators of a sudden change in their arousal state. However, reports evidencing associated internal physiological changes are rare. By homology with human "emotional" vocal productions (e.g., laughter and crying), we predicted that animal vocal productions may result in relaxing tenseness or excitement. In this study, 15 stallions equipped with a heart rate monitor were presented a mare at some distance so as to prevent contact, thereby increasing the males' arousal. Stallions' heart rates increased just before whinnying but returned to baseline rates whi...
Hopster K, Hopster-Iversen C, Geburek F, Rohn K, Kästner SB.The aim of this study was to assess the effect of duration of anaesthesia and concentration of isoflurane on global perfusion as well as intestinal microperfusion and oxygenation. Nine Warmblood horses were premedicated with xylazine; anaesthesia was induced with midazolam and ketamine, and maintained with isoflurane. Horses were ventilated to normocapnia. During 7 h of anaesthesia, mean arterial blood pressures (MAP), heart rate, central venous pressure, pulmonary artery pressure, expiratory isoflurane concentration (ETIso) and cardiac output using lithium dilution were measured; cardiac in...
Karrasch NM, Hubbell JA, Aarnes TK, Bednarski RM, Lerche P.This study compared cardiorespiratory variables in dorsally recumbent horses anesthetized with guaifenesin-ketamine-xylazine and spontaneously breathing 50% or maximal (> 90%) oxygen (O2) concentrations. Twelve healthy mares were randomly assigned to breathe 50% or maximal O2 concentrations. Horses were sedated with xylazine, induced to recumbency with ketamine-diazepam, and anesthesia was maintained with guaifenesin-ketamine-xylazine to effect. Heart rate, arterial blood pressures, respiratory rate, lithium dilution cardiac output (CO), inspired and expired O2 and carbon dioxide partial pr...
McKenzie EC, Di Concetto S, Payton ME, Mandsager RE, Arko M.To determine the effect of dantrolene premedication on various cardiovascular and biochemical variables and recovery in isoflurane-anesthetized horses. Methods: 6 healthy horses. Methods: Each horse was anesthetized twice with a 21- to 28-day washout period between anesthetic sessions. Food was not withheld from horses before either session. During each session, dantrolene (6 mg/kg in 2 L of water) or water (2 L) was administered via a nasogastric tube 1 hour before anesthesia was induced. Anesthesia was maintained with isoflurane for 90 minutes, during which blood gas analyses and lithium-dil...
Hiraga A, Sugano S.Since the first recording of electrocardiograms (ECGs) of a horse in Japan was carried out in 1944, studies on ECGs have been performed intensively. During the early stages of research from the 1950s to 1960s, leads to use for ECG recording were evaluated using several different approaches including unipolar leads, bipolar limb leads, and bipolar chest leads. Based on these studies, the AB lead, which is oriented along the long axis of the heart, became the standard reference method in Japan. Electrodes of the AB lead are placed on the upper 1/4th point along a straight line between the wither...
Ringmark S, Lindholm A, Hedenström U, Lindinger M, Dahlborn K, Kvart C, Jansson A.Training of Standardbred race horses aims to improve cardiovascular and metabolic functions but studies on the effects of different training strategies from breaking till racing are lacking. Sixteen horses with the goal to race as 3-year-olds were studied from breaking (1-year-olds) to December as 3-year-olds. Horses were allocated to either a control (C) or reduced (R) training program from 2 years of age. The aim was to evaluate the effect of reducing the distance of high intensity exercise by 30% with respect to velocity at lactate concentration 4 mmol/l (VLa4), blood lactate and cardiovasc...
Navas de Solis C, Dallap Schaer BL, Boston R, Slack J.The objectives of this investigation were to: (1) Determine if acute hemorrhage is associated with increased plasma cardiac troponin I (cTnI) concentration or cardiac arrhythmias, (2) to describe the types of arrhythmias and their clinical course in horses following acute hemorrhage, (3) to determine the ability of clinical or clinicopathological variables to predict an increase in cTnI concentration and the presence of arrhythmias, and (4) to determine the associations of cTnI and cardiac arrhythmias with outcome. Methods: Prospective observational study. Methods: Large animal veterinary teac...
Pollitt CC, Davies CT.The effect of alimentary carbohydrate overload on hoof temperature was investigated to determine the state of the sublamellar vasculature preceding the onset of equine laminitis. Hoof, core and ambient temperatures and heart rate were logged continuously in 21 mature Standardbred horses kept in an environmental chamber set at 10 degrees C. Recording hoof temperature was a successful, noninvasive, method to measure indirectly, shifts in digital blood flow against a background of cold induced, physiological, vasoconstriction. High hoof temperatures were assumed to indicate digital vasodilation a...
Cullen LK, Steffey EP, Bailey CS, Kortz G, da Silva Curiel J, Bellhorn RW, Woliner MJ, Elliott AR, Jarvis KA.The effects of different arterial carbon dioxide tensions (PaCO2) on cerebrospinal fluid pressure (CSFP) and intraocular pressure (IOP) were studied in 6 male halothane-anesthetized horses positioned in left lateral recumbency. Steady-state anesthetic conditions (1.06% end-tidal halothane concentration) commenced 60 minutes following anesthetic induction with only halothane in oxygen. During atracurium neuromuscular blockade, horses were ventilated, and respiratory rate and peak inspiratory airway pressure were maintained within narrow limits. The CSFP and IOP were measured at 3 different leve...
Farag AMM, Ibrahim HMM.Donkey (Equus asinus), the cheapest form of agricultural power in Egypt, is used principally as draught or pack animals and may also be ridden, or used for threshing, raising water, milling, and other work. The aim of the present study was to provide B-mode and M-mode echocardiographic reference ranges from a sample of population of donkeys (E. asinus) based on the probability theory and statistics. In the present study, B-mode and 2-dimensional guided M-mode echocardiography were performed on 44 clinically healthy donkeys (E. asinus) (22 males and 22 females), without any neither clinical nor...
Ennezat PV, Darchis J, Lamblin N, Tricot O, Elkohen M, Aumégeat V, Equine O, Dujardin X, Saadouni H, Le Tourneau T, de Groote P, Bauters C.Although mitral regurgitation (MR) has been associated with an increased risk of death and heart failure after myocardial infarction (MI), the relationship between post-MI MR and left ventricular (LV) remodeling has not been entirely clarified. In addition, the optimal timing for assessing MR after MI remains unknown. Methods: Post-MI MR was assessed by Doppler echocardiography at hospital discharge (baseline) and after 3 months in 261 patients with an inaugural anterior MI. We studied LV remodeling during a 1-year period and clinical follow-up after 3 years, according to MR severity at baseli...
Wong DM, Sponseller BA, Alcott CJ, Agbedanu PN, Wang C, Hsu WH.To evaluate the effect of IV administration of polymyxin B on clinical and serum biochemical variables in foals with experimental endotoxemia. Methods: Prospective experimental study. Methods: 14 healthy neonatal foals. Methods: Foals were randomly assigned to a treatment or control group and were administered a single dose of lipopolysaccharide (0.5 μg/kg [0.23 μg/lb]) IV over 30 minutes. The treatment group received polymyxin B (6,000 U/kg [2,727 U/lb], IV) immediately after completion of lipopolysaccharide infusion; the control group was administered an equal volume of saline (0.9% NaCl) ...
Morton AJ, Varney CR, Ekiri AB, Grosche A.N-butylscopolammonium bromide (NBB) and xylazine are commonly used medications for the treatment of spasmodic colic and other forms of abdominal pain in horses. Both NBB and xylazine exert significant effects on the cardiovascular system and other vital systems of horses. Objective: To evaluate the effects of i.v. administration of NBB, xylazine, and the combination of NBB and xylazine on heart rate, other commonly measured physiological parameters, cardiac rhythm and blood pressure. Methods: Six mature horses of mixed breed were used. In a random cross-over design, each horse was given 0.3 mg...
Munsters CC, Visser EK, van den Broek J, Sloet van Oldruitenborgh-Oosterbaan MM.Mounted police horses have to cope with challenging, unpredictable situations when on duty and it is essential to gain insight into how these horses handle stress to warrant their welfare. The aim of the study was to evaluate physiological and behavioral responses of 12 (six experienced and six inexperienced) police horses during police training. Horses were evaluated during four test settings at three time points over a 7-week period: outdoor track test, street track test, indoor arena test and smoke machine test. Heart rate (HR; beats/min), HR variability (HRV; root means square of successiv...
Wittenberg-Voges L, Kästner SB, Raekallio M, Vainio OM, Rohn K, Hopster K.To compare the effects of MK-467 during isoflurane anaesthesia combined with xylazine or dexmedetomidine on global and gastrointestinal perfusion parameters. Methods: Prospective, randomized experimental trial. Methods: A total of 15 warmblood horses. Methods: Horses were divided into two groups for administration of either dexmedetomidine (D) or xylazine (X) for premedication (D: 3.5 μg kg; X: 0.5 mg kg) and as constant rate infusion during isoflurane anaesthesia (D: 7 μg kg hour; X: 1 mg kg hour). During anaesthesia, heart rate, mean arterial blood pressure (MAP), systemic vascular resista...
Lo Feudo CM, Stucchi L, Cavicchioli P, Stancari G, Conturba B, Zucca E, Ferrucci F.To evaluate the association between the severity of dynamic upper airway obstruction (DUAO) and selected fitness parameters in Standardbred racehorses measured by treadmill test. 191 Standardbred racehorses that underwent a standardized diagnostic protocol for poor performance evaluation between 2002 and 2021 at the Veterinary Teaching Hospital, University of Milan. Horses underwent a diagnostic protocol including clinical examination, lameness evaluation, laboratory analyses, ECG, resting upper airway endoscopy, metabolic incremental treadmill test, high-speed treadmill endoscopy, postexercis...
Decloedt A, De Clercq D, Ven S, Vera L, van Loon G.The disproportionate rise of pulmonary artery pressure compared to systemic blood pressure during exercise can lead to detrimental right ventricular remodelling in endurance athletes. Horses may act as an extreme model of these athletic cardiovascular adaptations, as they show a three fold increase in pulmonary pressures during exercise. Right ventricular function was examined in ten healthy horses using post-exercise and pharmacological stress echocardiography in a randomised cross-over design. Exercise testing was performed on a treadmill while pharmacological testing was performed using an ...
Robertson JT, Muir WW, Sams R.The cardiopulmonary and behavioral effects of butorphanol were evaluated in pain-free adult horses. Butorphanol tartrate was administered IV in doses of 0.1, 0.2, and 0.4 mg/kg to the same horses on 3 separate occasions. There were no significant (P less than 0.05) changes in heart rate, mean and diastolic arterial pressure, mean and diastolic pulmonary arterial blood pressure, or cardiac output recorded in the horses given these doses. Systolic arterial blood pressure was significantly (P less than 0.05) increased in only the horses given the 0.2 mg/kg dose. Significant (P greater than 0.05) ...
Couroucé A, Geffroy O, Barrey E, Auvinet B, Rose RJ.Standardised exercise tests were performed at 2 different tracks and on an uninclined treadmill during the same week to determine the influence of exercise surface on different measured variables such as heart rate (HR), blood lactate concentration, packed cell volume, stride frequency, stride length, gait symmetry and regularity and on different derived physiological variables such as the speed at a HR of 200 beats/min (V200), the speed at a blood lactate concentration of 4 mmol/l (V4), the speed at a maximal HR (VHRmax). Five French Trotters, age 3 years, in training for 3 months prior to th...
Hesselkilde EZ, Almind ME, Petersen J, Flethøj M, Præstegaard KF, Buhl R.Despite increased focus on cardiac arrhythmias in horses, the nature and prevalence is still poorly described. Case reports suggest that arrhythmias occurring secondary to systemic disease are seen more commonly in the clinic than arrhythmias caused by cardiac disease. The aim of this study was to investigate the prevalence of arrhythmias in colic horses referred for hospital treatment. Associations between electrolyte disturbances and arrhythmias were also investigated. Results: Heart rate was 37.4 ± 3.7 bpm in the control group, and 51.6 ± 11.8 bpm, in the colic group, which was ...
Yamanaka T, Oku K, Koyama H, Mizuno Y.To clarify time-related changes in equine cardiovascular system during maintenance anesthesia (180 min, 1.2 minimum alveolar concentration) with sevoflurane (Sev-group) compared to isoflurane (Iso-group) as the basis for clinical use of Sev, horses were examined for the heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), systemic vascular resistance (SVR) and pre-ejection period (PEP)/ejection time (ET) that is an index of the cardiac contractility. The HR was almost 30 beats/min in both groups without significant temporal change. MAP was significantly elevated with time but the...
Goachet AG, Julliand V.Measurements of respiratory exchanges in genuine exercise conditions are undoubtedly of interest to further define the energy needs of endurance horses. However, the equine K4b2, the gas exchanges portable device validated for equines, has not been used in Arabian endurance horses yet. Therefore, the objective of this study was to implement field cardio-respiratory measurements in such horses using the equine K4b2 in order to assess energy expenditure (EE). Measurements of heart rate (HR), oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory frequency (RF), tidal volume (VT) and ...
Sedlinská M, Kabeš R, Novák M, Kološ F, Melková P.A five-month-old African jenny was presented with a history of exercise intolerance and syncopal episodes. Severe bradycardic arrhythmia due to a high-grade second-degree atrioventricular (AV) block with progression to complete AV block was diagnosed. The jenny underwent a transvenous single-chamber pacemaker implantation. The implantation procedure was performed in a lateral recumbency and the ventricular lead was inserted through the jugular vein. Positioning of the lead was guided by echocardiography. The pacemaker was programmed to VVI mode with a minimal ventricular rate of 40 pulses per ...
Wagner AE, Mama KR, Steffey EP, Hellyer PW.To determine whether infusion of xylazine (XYL) and ketamine (KET) for 30 minutes after isoflurane administration in horses would result in improved quality of recovery from anesthesia, without detrimental cardiopulmonary changes. Methods: Randomized, blinded experimental trial. Methods: Seven healthy adult horses aged 6.4 +/- 1.9 years and weighing 506 +/- 30 kg. Methods: Horses were anesthetized twice, at least 1 week apart. On both occasions, anesthesia was induced by the administration of XYL, diazepam, and KET, and maintained with isoflurane for approximately 90 minutes, the last 60 minut...
Manohar M, Hutchens E, Coney E.Catheter mounted micro-tip-manometers (the signals from which were matched with fluid-filled pressure signals from same cardiovascular sites and zeroed at the point of the shoulder), were used to study pulmonary haemodynamics in 8 healthy sound horses at rest and during exercise performed at 8, 10, 12 and 14 m/s on a treadmill. Measurements were made without frusemide (control) and 4 h after iv administration of 250 mg frusemide. Post-frusemide data were also obtained on a separate day, and these observations were not significantly different from those made on the same day as controls. Pre-fru...
Zuber N, Zuber M, Schwarzwald CC.Assessment of cardiac electromechanical function in horses requires training, experience and specialised equipment and does not allow continuous monitoring over time. Objective: The objective of this study was to establish the use of an acoustic ECG monitor (Audicor ) in healthy horses. It provides noninvasive, examiner-independent, continuous analyses combining ECG and phonocardiography to calculate indices of cardiac mechanical activity and haemodynamics. Device usability was investigated, reference intervals calculated and reproducibility of analyses assessed. Methods: Prospective descripti...
Love EJ, Lane JG, Murison PJ.To determine the effect of morphine administration on commonly monitored cardio-respiratory variables and recovery quality in horses undergoing anaesthesia and surgery. Methods: Prospective, randomized clinical study. Methods: Thirty-eight thoroughbred horses, 32 geldings and six mares, 3-13 years old, weighing 411-600 kg. Methods: A standard anaesthetic technique was used. Twenty minutes after induction of anaesthesia horses received 0.1 mg kg(-1) (0.1 m) or 0.2 mg kg(-1) (0.2 m) morphine by intravenous injection. A control group did not receive morphine. Heart rate, respiratory rate (fr), me...
Masko M, Domino M, Lewczuk D, Jasinski T, Gajewski Z.A treadmill is an important tool in the equine analysis of gait, lameness, and hoof balance, as well as for the evaluation of horse rehabilitation or poor performance including dynamic endoscopy. Before all of these uses, horses have to be habituated to a treadmill locomotion. We used principal component analysis to evaluate the relationship between aspects of the horse's temperament and emotional response, and progress in the behavioral habituation to a treadmill. Fourteen horses were tested, by the same familiar handler, using the novel object test, the handling test, and both positive and n...
Momozawa Y, Terada M, Sato F, Kikusui T, Takeuchi Y, Kusunose R, Mori Y.The aim of the study was to determine parameters reflecting equine anxiety trait by comparing results obtained in a behavior test and an anxiety score assessed by familiar caretakers in response to a questionnaire. In the behavior test, horses were individually led into a novel room by their caretakers and loosely tethered to decrease excessive movement using the common cross-tying technique with two leads and breakable plastic cords. The horses initially remained with their caretaker for 2 min; the caretaker then left and the subject animal was left alone for 2 min. The latency to break the p...
Lees P, Serrano L.1 The butyrophenone tranquilizer, azaperone, was administered intramuscularly, at dose levels of 0.4 and 0.8 mg/kg, to ponies and its effects on cardiovascular and respiratory functions assessed. 2 Arterial blood pH, CO2 tension (PaCO2) and O2 tension (PaO2) remained relatively constant throughout the course of action of azaperone. 3 Azaperone did not modify plasma protein concentration but venous blood packed cell volume and haemoglobin concentration were reduced by 5 to 10% for at least 4 hours. These changes were probably caused by uptake of erythrocytes into the splenic reservoir. 4 Small ...
Gramkow HL, Evans DL.Running ability of Thoroughbred racehorses is correlated with maximal oxygen uptake, and the velocity at maximal oxygen uptake is highly correlated with the velocity at maximal heart rate (VHRmax). Objective: To investigate the relationship between VHRmax and racing performance, expressed as 'peak dollars earned per race start'. Methods: Heart rate (HR) and velocity were recorded in 25 Thoroughbred racehorses during trotting and subsequent fast gallops in the field at velocities of 15-16 m/sec. Velocity was recorded by a global positioning system (GPS). Maximal HR (HRmax) and maximal velocity ...
Dhanjal JK, Wilson DV, Robinson E, Tobin TT, Dirikolu L, Dirokulu L.To determine the optimal dose, serum concentrations and analgesic effects of intravenous (IV) tramadol in the horse. Two-phase blinded, randomized, prospective crossover trial. Seven horses (median age 22.5 years and mean weight 565 kg). Horses were treated every 20 minutes with incremental doses of tramadol HCl (0.1-1.6 mg kg(-1)) or with saline. Heart rate, respiratory rate, step frequency, head height, and sweating, trembling, borborygmus and head nodding scores were recorded before and up to 6 hours after treatment. In a second study, hoof withdrawal and skin twitch reflex latencies (HWRL ...
Geor RJ, McCutcheon LJ.This study examined the effects of hyperhydration, exercise-induced dehydration, and oral fluid replacement on physiological strain of horses during exercise-heat stress. On three occasions, six horses completed a 90-min exercise protocol (50% maximal O2 uptake, 34.5 degrees C, 48% relative humidity) divided into two 45-min periods (exercise I and exercise II) with a 15-min recovery between exercise bouts. In random order, horses received no fluid (NF), 10 liters of water (W), or a carbohydrate-electrolyte solution (CE) 2 h before exercise and between exercise bouts. Compared with NF, preexerc...
Connysson M, Muhonen S, Lindberg JE, Essén-Gustavsson B, Nyman G, Nostell K, Jansson A.High-energy forage might be an alternative to concentrates for performance horses and such forage can be produced by an early cut. However, early cut forage is high in crude protein (CP), which may result in an excessive CP intake. Objective: To investigate how CP intake affects nitrogen (N), fluid and acid-base balance, and exercise response in horses fed high-energy forage diets. The hypothesis was that high CP intake causes acidosis, and alters fluid balance and response to intensive exercise. Methods: Two forage-only diets based on high-energy grass forage were fed for 23 days in a crossov...
Braun C, Trim CM, Eggleston RB.To investigate the impact of a change in body position on blood gases and arterial blood pressures in foals anesthetized with guaifenesin, ketamine, and xylazine. Methods: Prospective, randomized experimental study. Methods: Twelve Quarter Horse foals, age of 5.4 +/-0.9 months and weighing 222 +/- 48 kg. Methods: Foals were anesthetized with guaifenesin, ketamine, and xylazine for 40 minutes in lateral recumbency and then assigned to a change in lateral recumbency after hoisting (Group 1, n = 6), or no change (Group 2, n = 6). Oxygen 15 L minute(-1) was insufflated into the endotracheal tube t...
Clark L, Clutton RE, Blissitt KJ, Chase-Topping ME.To study the effects of morphine on haemodynamic variables, blood gas values and the requirement for additional anaesthetic drugs in horses undergoing surgery. Methods: Prospective randomized study. Methods: Thirty-eight client-owned horses, ASA(American Society of Anesthesiologists) category I or II, undergoing elective surgical procedures, were studied. Horses were divided between two groups, and were paired according to operation, anaesthetist, body position during surgery, mass and breed. Group M+ received morphine by intravenous (IV) injection (0.15 mg kg(-1)) before induction of anaesthe...
