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.
Hopster K, Wittenberg-Voges L, Kästner SBR.To investigate the effects of a xylazine infusion during isoflurane anesthesia on global perfusion parameters and gastrointestinal oxygenation and microperfusion, 8 adult warmblood horses were sedated with xylazine and anesthesia induced with midazolam and ketamine. Horses were mechanically ventilated during anesthesia. After 3 h of stable isoflurane anesthesia (FIso 1.3 Vol %), a xylazine infusion with 1 mg/kg body weight (BW) per hour was started for 1 h and then stopped. Before, during, and after xylazine infusion, heart rate (HR), arterial blood pressure (MAP), cardiac output (CO), central...
Carstensen H, Kjær L, Haugaard MM, Flethøj M, Hesselkilde EZ, Kanters JK, Pehrson S, Buhl R, Jespersen T.Antiarrhythmic compounds against atrial fibrillation (AF) often have reduced efficacy and may display cardiac and/or noncardiac toxicity. Efficacy can be improved by combining 2 compounds with distinct mechanisms, and it may be possible to use lower doses of each compound, thereby reducing the likelihood of adverse side effects. The purpose of this study was to investigate whether the effective doses of dofetilide and ranolazine can be reduced if the drugs are combined. Dofetilide, ranolazine, and a combination of these were administered in 4 incremental dosing regimens to horses with acutely ...
Lanata A, Guidi A, Valenza G, Baragli P, Scilingo EP.This study focuses on the analysis of human-horse dynamic interaction using cardiovascular information exclusively. Specifically, the Information Theoretic Learning (ITL) approach has been applied to a Human-Horse Interaction paradigm, therefore accounting for the nonlinear information of the heart-heart interplay between humans and horses. Heartbeat dynamics was gathered from humans and horses during three experimental conditions: absence of interaction, visual-olfactory interaction, and brooming. Cross Information Potential, Cross Correntropy, and Correntropy Coefficient were computed to qua...
Lenoir A, Trachsel DS, Younes M, Barrey E, Robert C.Analysis of the heart rate variability (HRV) gains more and more importance in the assessment of training practice and welfare in equine industry. It relies on mathematical analyses of reliably and accurately measured variations in successive inter-beat intervals, measured as RR intervals. Nowadays, the RR intervals can be obtained through two different techniques: a heart rate meter (HRM) or an electrocardiogram (ECG). The agreement and reliability of these devices has not been fully assessed, especially for recordings during exercise. The purpose of this study was to assess the agreement of ...
Reiners JK, Rossdeutscher W, Hopster K, Kästner SBR.The use of pulse oximetry in horses is limited due to inadequate readings with conventional transmission sensor probes. Objective: The objectives of this study were to 1) develop an improved sensor design for horses to be used at an appropriate anatomical site, and 2) evaluate this design in an experimental study. Methods: In vivo experiment. Methods: A new sensor design for reflectance pulse oximetry at the buccal mucosa was developed. A conventional Nonin 2000SL sensor for transmission pulse oximetry was included into this design. Three different prototypes (N1, N2a, N2b) were constructed an...
Ohmura H, Jones JH.We investigated changes in heart rate (HR) and HR variability as a function of age in newborn foals to old Thoroughbred horses. Experiments were performed on a total of 83 healthy and clinically normal Thoroughbred horses. Resting HR decreased with age from birth. The relationship between age and HR fit the equation Y=48.2X(R=0.705); the relationship between age and HR for horses 0-7 years old fit the equation Y=44.1X(R=0.882). Seven-day-old horses had the highest HR values (106 ± 10.3 beat/min). The low frequency (LF) and high frequency (HF) powers increased with age in newborn to old horses...
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...
Pohlin F, Brabender K, Fluch G, Stalder G, Petit T, Walzer C. Ecosystems with seasonal fluctuations in climate and food availability present physiological challenges to resident mammals and may cause "stress." The two predominant physiological responses to stressors are (1) the activation of the hypothalamic-pituitary-adrenal axis and (2) the modulation of the autonomic nervous system. To date, the primary indicator for "stress" in wildlife- and zoo animal research are glucocorticoid levels. By measuring the autonomic regulation of cardiac activity, particularly the vagal tone, heart rate variability (HRV) is presently emerging as a suitable indicator o...
Dancker C, Hopster K, Rohn K, Kästner SB.In the horse, effects of cardiovascular-active drugs on local perfusion of the gastrointestinal tract are poorly understood. Objective: To determine the effect of drugs commonly used to support blood pressure, on local intestinal blood flow and tissue oxygenation under isoflurane anaesthesia. Methods: In vivo randomised crossover experiment. Methods: Ten horses were anaesthetised with isoflurane. After 90 min of equilibration three doses (μg/kg bwt/min) of dobutamine (DOB 0.5/1/3), dopamine (DA 1/2/5), noradrenaline (NA 0.1/0.2/0.5) and phenylephrine (PHE 0.5/1/3) were infused for 15 min, in ...
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 ...
Knych HK, Stanley SD, McKemie DS, Arthur RM, Bondesson U, Hedeland M, Thevis M, Kass PH.Although developed as a therapeutic medication, meldonium has found widespread use in human sports and was recently added to the World Anti-Doping Agency's list of prohibited substances. Its reported abuse potential in human sports has led to concern by regulatory authorities about the possible misuse of meldonium in equine athletics. The potential abuse in equine athletes along with the limited data available regarding the pharmacokinetics and pharmacodynamics of meldonium in horses necessitates further study. Eight exercised adult thoroughbred horses received a single oral dose of 3.5, 7.1, ...
Lage J, Fonseca MG, de Barros GGM, Feringer-Júnior WH, Pereira GT, Ferraz GC.This study aimed to characterize the maximum heart rate (HR) and the intensity of official marcha contests (OMC) and to compare the cost of transport (COT) and metabolic power (Pmet) of Mangalarga Marchador (MM) horses of marcha batida (MB) and marcha picada (MP) gaits. Twenty-two MM horses participated in this study. The experiment was conducted in 3 phases: 1) maximum effort test (MET), 2) OMC, and 3) standardized marcha test (SMT). To characterize the HR, 19 horses (14 MB and 5 MP) underwent a MET. Of those, 13 (9 MB and 4 MP) were monitored during the OMC, which consisted of 4 stages: marc...
Davie AJ, Wen L, Cust ARE, Beavers R, Fyfe T, Zhou S.This study investigated the effects of six weeks of normobaric hypoxic training on transcriptional expression of the genes associated with mitochondrial and glycolytic activities in Thoroughbred horses. Eight horses were divided into two groups of four. They completed an identical incremental, moderate intensity training program, except that one group trained in a hypoxic chamber with 15% oxygen for 30 min on alternate days except Sundays (HT), while the other group trained in normal air (NC). Prior to and post training, heart rate and blood lactate were measured during an incremental treadm...
Brinkmann L, Riek A, Gerken M.Domesticated horses are increasingly kept under semi-natural housing conditions, whereas their adaptation capacity is not fully investigated. In all, 10 Shetland pony mares were held under semi-extensive conditions for 1 year. In winter animals were allocated into two feeding groups (60% and 100% of maintenance energy requirement, respectively). Triiodothyronine, thyroxine, non-esterified fatty acids (NEFA), total bilirubin, total protein, triglyceride, glucose, insulin and hair length were measured at monthly intervals, whereas BW, body condition score, cresty neck score and resting heart rat...
Bonelli F, Sgorbini M, Meucci V, Sighieri C, Baragli P.Low intensity exercise increases insulin-stimulated glucose uptake in skeletal muscle and decreases its plasma concentration. In this study, plasma insulin and glucose concentrations were evaluated 5min before and 5, 15, 25, 35, 45 and 60min after an IV bolus of glucose in 12 Thoroughbreds before and after 1 month of submaximal aquatraining exercise, monitored using heart rate and blood lactate. Plasma glucose concentrations were evaluated using a colorimetric enzymatic method, and plasma insulin concentrations with a solid-phase radioimmunoassay method. Pre-training plasma glucose concentrati...
Ricard A, Robert C, Blouin C, Baste F, Torquet G, Morgenthaler C, Rivière J, Mach N, Mata X, Schibler L, Barrey E.Endurance horses are able to run at more than 20 km/h for 160 km (in bouts of 30-40 km). This level of performance is based on intense aerobic metabolism, effective body heat dissipation and the ability to endure painful exercise. The known heritabilities of endurance performance and exercise-related physiological traits in Arabian horses suggest that adaptation to extreme endurance exercise is influenced by genetic factors. The objective of the present genome-wide association study (GWAS) was to identify single nucleotide polymorphisms (SNPs) related to endurance racing performance in 597 Ara...
Schmidt K, Deichsel K, de Oliveira RA, Aurich J, Ille N, Aurich C.We hypothesized that housing of stallions in a thermoneutral temperature zone during autumn and winter does not only influence metabolism and hair shedding but also improves the characteristics of raw and processed semen. Fertile Shetland pony stallions were followed from October to June. This time coincided with the seasons autumn, winter and spring. Ponies were kept in outside paddocks (group CON, n = 8) or in indoor stables (group ST, n = 8) from October to March when ST stallions returned to outdoor paddocks, but ponies remained in the same groups. The rectal temperature was measured o...
Sacks M, Ringer SK, Bischofberger AS, Berchtold SM, Bettschart-Wolfensberger R.To compare the effects of two balanced anaesthetic protocols (isoflurane-dexmedetomidine versus medetomidine) on sedation, cardiopulmonary function and recovery in horses. Methods: Prospective, blinded, randomized clinical study. Methods: Sixty healthy adult warm blood horses undergoing elective surgery. Methods: Thirty horses each were sedated with dexmedetomidine 3.5 μg kg (group DEX) or medetomidine 7 μg kg (group MED) intravenously. After assessing and supplementing sedation if necessary, anaesthesia was induced with ketamine/diazepam and maintained with isoflurane in oxygen/air and ...
Broux B, De Clercq D, Decloedt A, Ven S, Vera L, van Steenkiste G, Mitchell K, Schwarzwald C, van Loon G.Atrial fibrillation (AF) is the most common pathological arrhythmia in horses. After successful treatment, recurrence is common. Heart rate monitors are easily applicable in horses and some devices offer basic heart rate variability (HRV) calculations. If HRV can be used to distinguish between AF and sinus rhythm (SR), this could become a monitoring tool for horses at risk for recurrence of AF. Objective: The purpose of this study was to assess whether in horses AF (before cardioversion) and SR (after cardioversion) can be differentiated based upon HRV parameters. Methods: Cohort study with in...
Heliczer N, Gerber V, Bruckmaier R, van der Kolk JH, de Solis CN.OBJECTIVE To determine whether hypertension, high sympathetic tone, resting and exercising arrhythmias, and echocardiographic changes consistent with hypertensive cardiomyopathy were associated with equine metabolic syndrome (EMS) in ponies. DESIGN Prospective case-control study. ANIMALS 19 privately owned ponies with a diagnosis of EMS (history of laminitis, body condition score ≥ 7/9, cresty neck score ≥ 3/5, and abnormal oral sugar test result; cases) and 20 healthy control ponies. PROCEDURES Heart rate (HR), noninvasively measured arterial blood pressure (BP), markers of autonomic tone...
Kahn MK, Coverdale JA, Leatherwood JL, Arnold CE, Dabareiner RA, Bradbery AN, Millican AA, Welsh TH.Eighteen Quarter Horses were used in a randomized complete design for a 28-d experiment to evaluate age-related effects on inflammation and cartilage turnover after induction of a single inflammatory insult using lipopolysaccharide (LPS). Horses were grouped by age as yearlings (3 males and 3 females), 2 to 3 yr olds (2/3 yr old; 2 males and 4 females), and skeletally mature 5 to 8 yr olds (mature; 2 males and 4 females). On d 0, all horses were individually housed and fed diets that met or exceeded requirements. On d 14, horses were challenged with an intra-articular injection of LPS. Radial ...
Fenner K, Webb H, Starling MJ, Freire R, Buckley P, McGreevy PD.Rein tension is used to apply pressure to control both ridden and unridden horses. The pressure is delivered by equipment such as the bit, which may restrict voluntary movement and cause changes in behavior and physiology. Managing the effects of such pressure on arousal level and behavioral indicators will optimise horse learning outcomes. This study examined the effect of training horses to turn away from bit pressure on cardiac outcomes and behavior (including responsiveness) over the course of eight trials in a standardised learning task. The experimental procedure consisted of a resting p...
Hiraga A, Sugano S.Although the total number of horses raised in Japan dramatically decreased after World War II, because draft horses were still used for farm work in paddy fields and on farms during the period of the 1950s and 1960s, a performance test for selecting better draft horses was needed. In order to determine the most suitable size of draft horses for Japanese farm conditions, the working power of horses weighing from 185 to 622 kg was evaluated by performing an endurance test, several kinds of working power tests, and maximum pulling power tests. Oxygen consumption during draft exercise was measured...
Sleeper MM.Heart disease can be defined as any abnormality of the heart whether it is a cardiac dysrhythmia or structural heart disease, either congenital or acquired. Heart failure occurs when a cardiac abnormality results in the inability of the heart to pump enough blood to meet the body's needs. Heart disease can be present without leading to heart failure. Heart failure, however, is a consequence of heart disease. There are 4 main areas where the clinician can intervene to improve cardiac output with heart failure: preload, afterload, myocardial contractility, and heart rate.
Heliczer N, Mitchell K, Lorello O, Dauvillier J, Burger D, Schwarzwald CC, Navas de Solis C.A 20-year-old warmblood breeding stallion presented to a University practice for semen collection and evaluation was incidentally diagnosed with atrial fibrillation (AF). Electrocardiogram recordings during breeding revealed inappropriately rapid tachycardia and occasional ventricular premature depolarizations/aberrant ventricular conduction. Transvenous electrical cardioversion was performed. After successful cardioversion the horse displayed supraventricular ectopy and atrial contractile dysfunction and was administered sotalol hydrochloride in an attempt to decrease the risk of AF recurrenc...
Stefánsdóttir GJ, Gunnarsson V, Roepstorff L, Ragnarsson S, Jansson A.This study examined the effect of increasing BW ratio (BWR) between rider and horse, in the BWR range common for Icelandic horses (20% to 35%), on heart rate (HR), plasma lactate concentration (Lac), BWR at Lac 4 mmol/l (W4), breathing frequency (BF), rectal temperature (RT) and hematocrit (Hct) in Icelandic horses. In total, eight experienced school-horses were used in an incremental exercise test performed outdoors on an oval riding track and one rider rode all horses. The exercise test consisted of five phases (each 642 m) in tölt, a four-beat symmetrical gait, at a speed of 5.4±0.1 m/s (...
Lanata A, Guidi A, Valenza G, Baragli P, Scilingo EP.We present a study focused on a quantitative estimation of a human-horse dynamic interaction. A set of measures based on magnitude and phase coupling between heartbeat dynamics of both humans and horses in three different conditions is reported: no interaction, visual/olfactory interaction and grooming. Specifically, Magnitude Squared Coherence (MSC), Mean Phase Coherence (MPC) and Dynamic Time Warping (DTW) have been used as estimators of the amount of coupling between human and horse through the analysis of their heart rate variability (HRV) time series in a group of eleven human subjects, a...
Vincze B, Gáspárdy A, Kovács L, Albert E, Kézér L, Baska F, Szenci O.Transabdominal ultrasonography has been shown to be a useful and reliable method for assessing fetal well-being in horses and cattle. To test the applicability of fetal aortic diameter measurement in cattle, 44 late-term pregnant cows and heifers were examined 21 to 0 days prior to calving. Mean fetal aortic diameter was 2.07 ± 0.14 cm and mean fetal heart rate (FHR) was 109 ± 17 bpm. Three dead calves were dissected and their aortic diameter was measured in a water bath. The mean birth weight (n = 44) was 39.9 ± 5.8 kg. There was a significant negative correlation between FHR and fetal aor...
Ohmura H, Mukai K, Takahashi T, Aida H, Jones JH.OBJECTIVE To determine cardiorespiratory responses of Thoroughbreds to uphill and downhill locomotion on a treadmill at identical gradients. ANIMALS 5 highly trained Thoroughbred geldings. PROCEDURES Thoroughbreds were exercised for 2-minute intervals on a treadmill at 1.7, 3.5, 6.0, 8.0, and 10.0 m/s at a 4% incline, 0% incline (horizontal plane), and 4% decline in random order on different days. Stride frequency, stride length, and cardiopulmonary and O-transport variables were measured and analyzed by means of repeated-measures ANOVA and Holm-Šidák pairwise comparisons. RESULTS Horses com...
Cruz Benedetti IC, Nottrott K, Fourel I, Le Bris M, Mongellas E, Portier K.To compare the effects of a lidocaine constant rate infusion (CRI) combined with 1% isoflurane versus those of 2% isoflurane alone on cardiovascular variables in anaesthetized horses, and to estimate the sample size required to detect a difference in recovery quality. Methods: Prospective, randomized, blinded, crossover study. Methods: Twelve healthy experimental horses. Methods: Horses were anaesthetized twice using an intravenous (IV) administration of acepromazine, romifidine, diazepam and ketamine. Horses were placed in dorsal recumbency and ventilated mechanically. During the first 10 min...
Holdstock NB, Ousey JC, Rossdale PD.The aim of this study was to determine glomerular filtration rate (GFR), effective renal plasma flow (RPF) and filtration fraction (FF) values in Pony foals during the first 10 days post partum in order to assess any age-related changes and the reliability of the single injection inulin/p-aminohippurate (PAH) method. Arterial blood pressure and pulse rate were determined in Pony and Thoroughbred (TB) foals during the first 10 days post partum to establish age-related changes, differences between breeds and possible interrelationships with GFR and RPF. Inulin and PAH were injected intravenously...
Pascoe JR, Hiraga A, Hobo S, Birks EK, Yarbrough TB, Takahashi T, Hada T, Aida H, Steffey EP, Jones JH.Eight horses were fitted surgically with 8 ultrasonic sonomicrometer crystals each attached to their left ventricular pericardia and a left atrial catheter. Three horses returned to treadmill performance with a maximum rate of oxygen consumption similar to their presurgical values. These horses were evaluated to determine how well sonomicrometer estimates of cardiac output agreed with those obtained by a steady-state method, the Fick principle. Variance between the 2 was similar to the coefficient of variation (approximately 12.5%) of the Fick estimates. We conclude that left ventricular sonom...
de Vries A, Brearley JC, Taylor PM.Volatile agent-induced hypotension may contribute to anaesthetic-related morbidity and mortality in horses. Dobutamine is commonly used to support arterial blood pressure (ABP) but little is known about its cardiovascular effects under clinical conditions. The aim of this clinical study was to elucidate the relationship between cardiovascular function and dobutamine infusion in isoflurane-anaesthetized horses. Forty-four horses anaesthetized for a variety of surgical procedures were studied. Premedication with acepromazine, methadone and detomidine was followed by induction of anaesthesia with...
Schwarzwald CC, Hamlin RL, Bonagura JD, Nishijima Y, Meadows C, Carnes CA.Although atrial arrhythmias are clinically important in horses, atrial electrophysiology has been incompletely studied. Objective: Standard electrophysiologic methods can be used to study drug effects in horses. Specifically, the effects of diltiazem on atrioventricular (AV) nodal conduction are rate-dependent and allow control of ventricular response rate during rapid atrial pacing in horses undergoing quinidine treatment. Methods: Fourteen healthy horses. Methods: Arterial blood pressure, surface electrocardiogram, and right atrial electrogram were recorded during sinus rhythm and during pro...
Carstensen H, Nissen SD, Saljic A, Hesselkilde EM, van Hunnik A, Hohl M, Sattler SM, Fløgstad C, Hopster-Iversen C, Verheule S, Böhm M, Schotten U....Atrial fibrillation (AF) is more prevalent in athletes, and currently, the mechanisms are not fully understood. Atrial fibrillation inducibility and stability was investigated in trained and untrained Standardbred racehorses. The horses underwent echocardiography for evaluation of atrial size. High-density mapping during AF was performed, and the presence of structural remodeling, as well as the expression of inflammatory and pro-inflammatory markers in the atria, was studied. Atrial fibrillation sustained significantly longer after tachypacing in the trained horses, whereas no difference in A...
Nagel C, Aurich J, Aurich C.Heart rate is an important parameter of fetal well-being. We have analyzed fetal heart rate (HR) and heart rate variability (HRV) by fetomaternal electrocardiography (ECG) in the horse (Equus caballus) from midpregnancy to foaling. It was the aim of the study to detect changes in the regulation of fetal cardiac activity over time and to establish normal values in undisturbed pregnancies. A total of 22 mares were available for the study. Fetomaternal electrocardiography was a reliable technique to detect cardiac signals in fetuses between Day 173 of gestation and foaling. Fetal HR decreased fro...
McCrae P, Spong H, Rutherford AA, Osborne V, Mahnam A, Pearson W.Electrocardiography (ECG) is an essential tool in assessing equine health and fitness. However, standard ECG devices are expensive and rely on the use of adhesive electrodes, which may become detached and are associated with reduced ECG quality over time. Smart textile electrodes composed of stainless-steel fibers have previously been shown to be a suitable alternative in horses at rest and during exercise. The objective of this study was to compare ECG quality using a smart textile girth band knit with silver and carbon yarns to standard adhesive silver/silver chloride (Ag/AgCl) electrodes. S...
Sysel AM, Pleasant RS, Jacobson JD, Moll HD, Modransky PD, Warnick LD, Sponenberg DP, Eyre P.Amphotericin B-induced synovitis of the left tarsocrural joint was used to create a grade 3 of 4 lameness in 11 horses. Caudal epidural catheters were placed and advanced to the lumbosacral region. Baseline heart and respiratory rates were recorded and horses were videotaped at a walk and trot. Morphine sulphate (0.2 mg/kg) and detomidine hydrochloride (30 micrograms/kg) were administered to treated horses (n = 8) through the epidural catheter; an equivalent volume of physiologic saline solution was administered to control horses (n = 3) through the catheter. At hourly intervals after epidural...
Kjeldsen ST, Nissen SD, Buhl R, Hopster-Iversen C.Atrial fibrillation (AF) is the most common arrhythmia in horses causing poor performance. As in humans, the condition can be intermittent in nature, known as paroxysmal atrial fibrillation (pAF). This review covers the literature relating to pAF in horses and includes references to the human literature to compare pathophysiology, clinical presentation, diagnostic tools and treatment. The arrhythmia is diagnosed by auscultation and electrocardiography (ECG), and clinical signs can vary from sudden loss of racing performance to reduced fitness or no signs at all. If left untreated, pAF may prom...
Manohar M, Goetz TE.The present study was carried out to examine the effects of nitric oxide synthase inhibition with Nomega-nitro-L-arginine methyl ester (L-NAME) on the right atrial as well as on the pulmonary arterial, capillary, and venous blood pressures of horses during rest and exercise performed at maximal heart rate (HRmax). Experiments were carried out on seven healthy, sound, exercise-trained Thoroughbred horses. Using catheter-tip manometers, with signals referenced at the point of the shoulder, we determined phasic and mean right atrial and pulmonary vascular pressures in two sets of experiments [con...
Léguillette R, Bond SL, Lawlor K, Haan T, Weber LM.A greater understanding of exercise physiology and biochemistry is required for the sport horse disciplines, including show jumping. Conditioning of horses for show jumping is empirical because they are primarily trained on flat ground, however the equivalent workload between jumping and flat work is currently unknown. The objectives of the study were therefore to compare the physiological demands of Warmblood show jumpers over a standardized 1.10 m course vs a 600 m standardized incremental exercise test on flat ground, and to report reference field test values for competitive show jumpin...
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...
Hamra JG, Kamerling SG, Wolfsheimer KJ, Bagwell CA.Diurnal variation in nociceptive sensitivity and plasma immunoreactive beta-endorphin (ir-BEND) concentrations was examined in eight healthy Thoroughbred horses. Pain thresholds, ir-BEND concentrations, rectal temperature, heart rate, respiratory rate and pupil diameter were measured over a 24 hour period. Nociceptive sensitivity was determined using two objective measures of pain: the skin-twitch reflex latency and the hoof withdrawal reflex latency. Significant variation in both nociceptive thresholds and ir-BEND concentrations were noted over the 24 hour period, with elevated pain threshold...
McGuirk SM, Muir WW.Cardiac arrhythmias are probably more common in horses than in any other domestic animal species. The most frequent clinical complaint associated with cardiac arrhythmias is exercise intolerance. Physical examination is characterized by auscultation abnormalities such as fast or slow heart rate, irregular rhythm, extra sounds, long pauses, or abnormal heart sounds. The electrocardiogram is used to make a definitive diagnosis of the dysrhythmia. Other laboratory and cardiac function tests are employed to determine the etiology and to assess the significance of the arrhythmia. Antiarrhythmic the...
McKeever KH, Hinchcliff KW, Reed SM, Robertson JT.Six intact (IN) and six splenectomized (SP) mares were subjected to an incremental exercise test to examine the role of decreases in plasma volume (PV) in the changes in hematocrit (Hct) normally seen with exercise. Each horse underwent an incremental exercise test in which it ran on a treadmill up a fixed incline of 6 degrees. The test started at a speed of 4 m/s, and speed was increased 1 m/s each min until heart rate reached a plateau. Blood samples were obtained at rest and at the end of the 4, 5, 6, and 7 m/s steps of the exercise test. Resting PV was greater (P < 0.05) in the IN group...
Rosselot P, Mendonça T, González I, Tadich T.Non-invasive measures are preferred when assessing animal welfare. Differences in behavioral and physiological responses toward a stressor could be the result of the selection of horses for specific uses. Behavioral and physiological responses of working and Chilean rodeo horses subjected to a handling test were assessed. Five behaviors, number of attempts, and the time to cross a bridge were video recorded and analyzed with the Observer XT software. Heart rate (HR) and heart rate variability (HRV), to assess the physiological response to the novel stimulus, were registered with a Polar Equine...
Janczarek I, Stachurska A, Kędzierski W, Pawlak EW, Wilk I, Zyglewska K, Paszkowska A, Ryżak M, Wiśniewska A.The current predation threat of domestic horses is generally low, and horses do not know predators' frightening cues. We studied whether horses still recognise predation threats. The aim of the study was to analyse the emotional response of purebred Arabian horses (Arabian) and Polish Konik horses (Konik) to an Arabian panther (Panthera pardus nimr) (panther) growl and a grey wolf (Canis lupus) (wolf) howl. Panther vocalisation was known to Arabian ancestors, whereas ancestors of Konik knew wolf vocalisation. The response to the howls of golden jackals (Canis aureus) (jackal), which did not pr...
Tapio H, Raekallio MR, Mykkänen A, Männikkö S, Scheinin M, Bennett RC, Vainio O.Medetomidine suppresses cardiovascular function and reduces gastrointestinal motility in horses mainly through peripheral α -adrenoceptors. Vatinoxan, a peripheral α -antagonist, has been shown experimentally to alleviate the adverse effects of some α -agonists in horses. However, vatinoxan has not been investigated during constant-rate infusion (CRI) of medetomidine in standing horses. Objective: To evaluate effects of vatinoxan on cardiovascular function, gastrointestinal motility and on sedation level during CRI of medetomidine. Methods: Experimental, randomised, blinded, cross-over stud...
Bettschart-Wolfensberger R, Dicht S, Vullo C, Frotzler A, Kuemmerle JM, Ringer SK.To test if the addition of butorphanol by constant rate infusion (CRI) to medetomidine-isoflurane anaesthesia reduced isoflurane requirements, and influenced cardiopulmonary function and/or recovery characteristics. Methods: Prospective blinded randomised clinical trial. Methods: 61 horses undergoing elective surgery. Methods: Horses were sedated with intravenous (i.v.) medetomidine (7 μg kg(-1)); anaesthesia was induced with i.v. ketamine (2.2 mg kg(-1)) and diazepam (0.02 mg kg(-1)) and maintained with isoflurane and a CRI of medetomidine (3.5 μg kg(-1) hour(-1)). Group MB (n = 31) receive...
Trachsel DS, Bitschnau C, Waldern N, Weishaupt MA, Schwarzwald CC.Frequent supraventricular or ventricular arrhythmias during and after exercise are considered pathological in horses. Prevalence of arrhythmias seen in apparently healthy horses is still a matter of debate and may depend on breed, athletic condition and exercise intensity. Objective: To determine intra- and interobserver agreement for detection of arrhythmias at rest, during and after exercise using a telemetric electrocardiography device. Methods: The electrocardiogram (ECG) recordings of 10 healthy Warmblood horses (5 of which had an intracardiac catheter in place) undergoing a standardised ...
Connysson M, Muhonen S, Jansson A.This study investigated the effects of transport and diet on metabolic response during a subsequent race-like test in Standardbred horses in training fed a forage-only diet and a 50:50 forage:oats diet. Six trained and raced Standardbred trotter mares were used. Two diets, 1 forage-only diet (FONLY) and 1 diet with 50% of DM intake from forage and 50% from oats (FOATS), were fed for two 29-d periods in a crossover design. At Day 21, the horses were subjected to transport for 100 km before and after they performed an exercise test (transport test [TT]). At Day 26, the horses performed a control...
Welch-Huston B, Durward-Akhurst S, Norton E, Ellingson L, Rendahl A, McCue M.Cardiac arrhythmias are commonly auscultated during routine physical examinations in horses and determining the underlying electrical abnormality using an ECG is important. The most commonly used device is a three-lead base apex system (Televet), however few practitioners carry this for routine visits. With recognition of the utility of smartphone-based ECGs in humans, dogs and ruminants, the AliveCor single-lead bipolar smartphone-based ECG has gained popularity. The objective of this study was to determine if AliveCor and Televet ECG measurements were comparable in healthy horses using multi...
Vainionpää MH, Raekallio MR, Pakkanen SA, Ranta-Panula V, Rinne VM, Scheinin M, Vainio OM.To investigate plasma drug concentrations and the effect of MK-467 (L-659'066) on sedation, heart rate and gut motility in horses sedated with intravenous (IV) detomidine. Methods: Experimental randomized blinded crossover study. Methods: Six healthy horses. Methods: Detomidine (10 μg kg(-1) IV) was administered alone (DET) and in combination with MK-467 (250 μg kg(-1) IV; DET + MK). The level of sedation and intestinal sounds were scored. Heart rate (HR) and central venous pressure (CVP) were measured. Blood was collected to determine plasma drug concentrations. Repeated measures anova was ...
Whitehair KJ, Steffey EP, Willits NH, Woliner MJ.To study behavioral and cardiopulmonary characteristics of horses recovering from inhalation anesthesia, 6 nonmedicated horses were anesthetized under laboratory conditions on 3 different days, with either halothane or isoflurane in O2. Anesthesia was maintained at constant dose (1.5 times the minimum alveolar concentration [MAC]) of halothane in O2 for 1 hour (H1), halothane in O2 for 3 hours (H3), or isoflurane in O2 for 3 hours (I3). The order of exposure was set up as a pair of Latin squares to account for horse and trial effects. Circulatory (arterial blood pressure and heart rate) and re...
Christensen JW, Bathellier S, Rhodin M, Palme R, Uldahl M.Recent studies have reported significant alterations in horse physiological and gait parameters when exposed to increased rider weight during moderate to high intensity exercise. This study aimed to evaluate the effect of increased rider weight (+15% and +25% of the regular rider's bodyweight) on horse behavioral, physiological and gait symmetry parameters during a standard dressage test. Twenty rider-horse equipages performed the same test three times in a randomized, crossover design. Salivary cortisol (SC), heart rate (HR), heart rate variability (HRV), behavior and gait symmetry (GS) were ...
Meyer GA, Lin HC, Hanson RR, Hayes TL.This study aimed to identify blood serum lidocaine concentrations in the horse which resulted in clinical signs of intoxication, and to document the effects of toxic levels on the cardiovascular and cardiopulmonary systems. Nineteen clinically normal mature horses of mixed breed, age and sex were observed. Lidocaine administration was initiated in each subject with an i.v. loading dose of 1.5 mg/kg bwt and followed by continuous infusion of 0.3 mg/kg bwt/min until clinical signs of intoxication were observed. Intoxication was defined as the development of skeletal muscle tremors. Prior to admi...
Holmes JR, Alps BJ.Theoretical consideration has been given in two horses to the properties of the electric field created by the equine heart acting as a simple electric generator. The principles of the vectorial theory have been applied to test the validity of application of the dipole concept. The cardiac electric forces, althrough complex in the immediate region of the heart, appear at the body surface in a similar form to those arising from a relatively immobile, single equivalent dipole. The potential value of the technique of vectorcardiography in cardiological investigations is briefly discussed.
Mama KR, Grimsrud K, Snell T, Stanley S.Detomidine hydrochloride is used to provide sedation, muscle relaxation and analgesia in horses, but a lack of information pertaining to plasma concentration has limited the ability to correlate drug concentration with effect. Objective: To build on previous information and assess detomidine for i.v. and i.m. use in horses by simultaneously assessing plasma drug concentrations, physiological parameters and behavioural characteristics. Objective: Systemic effects would be seen following i.m. and i.v. detomidine administration and these effects would be positively correlated with plasma drug con...
Driscoll N, Baia P, Fischer AT, Brauer T, Klohnen A.Large colon resection and anastomosis (LCRA) is the most aggressive method of surgical management of a colon with questionable viability. Currently, published studies are comprised mostly of broodmares and discuss short-term survival. Objective: To determine the prognosis for survival after LCRA in a diverse population of horses, report the incidence of post operative complications, and determine if associations between analysed variables and survival rate exist. Methods: The medical records of 52 horses that underwent LCRA were evaluated. Data were used to identify univariable associations wi...
Cabiddu R, Borghi-Silva A, Trimer R, Trimer V, Ricci PA, Italiano Monteiro C, Camargo Magalhães Maniglia M, Silva Pereira AM, Rodrigues das Chagas G....Neurological disorders are associated with autonomic dysfunction. Hippotherapy (HT) is a therapy treatment strategy that utilizes a horse in an interdisciplinary approach for the physical and mental rehabilitation of people with physical, mental and/or psychological disabilities. However, no studies have been carried out which evaluated the effects of HT on the autonomic control in these patients. Therefore, the objective of the present study was to investigate the effects of a single HT session on cardiovascular autonomic control by time domain and non-linear analysis of heart rate variabilit...
