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.
Parks C, Manohar M, Lundeen G.To examine the effects of tachycardia on coronary circulation, transmural distribution of myocardial blood flow (MBF, 15-micron diameter radionuclide-labeled microspheres) was studied in six healthy adult ponies at rest (heart rate = 60 +/- 7 beats . min-1), during ventricular pacing at 150 and 200 beats . min-1, as well as with ventricular pacing at 250 beats . min-1 before and during maximal coronary vasodilatation (iv adenosine infusion; 4 mumole . kg-1 . min-1). Mean aortic pressure and cardiac output were unchanged from control values with ventricular pacing. Whereas ventricular pacing at...
Thomas DP, Fregin GF, Gerber NH, Ailes NB.The effects of 5- and 10-wk treadmill exercise training on cardiorespiratory function were evaluated in the horse. Cardiac output (Q), heart rate (HR), and stroke volume (SV), as well as left ventricular (LVP), aortic (AoP), and mean right atrial (RAP) pressures and the peak first time derivative of LVP (LV dP/dtmax), were measured at rest and at five different levels of exercise up to 90% of initial predicted maximal HR (HRmax). Oxygen uptake (VO2) and respiratory exchange ratio (R) were also obtained under the same conditions. At rest, although HR was no different after training, LV dP/dtmax...
Bossut DF, Leshin LS, Stromberg MW, Malven PV.Electro-acupuncture (EA) treatment of horses to induce cutaneous analgesia also increased plasma concentrations of beta-endorphin (beta-EP) and cortisol. The magnitude of these increases did not relate consistently to the degree of EA-induced analgesia. Respiration and heart rates were also markedly increased during EA treatment. Intact female horses had higher packed cell volume and plasma beta-EP as well as lower plasma total protein than castrated male horses. Plasma cortisol, heart rate, and respiration rate did not differ significantly between sexes. None of the parameters measured before...
Muir WW, Wade A, Grospitch B.Systolic, diastolic, and mean arterial blood pressures and heart rate were determined in 73 horses, using an indirect automatic oscillometric technique. Blood pressure and heart rate data obtained by sphygmomanometry were compared with similar data obtained from cannulation of the horses' facial or dorsal metatarsal arteries. Good correlation between direct (actual) and indirect (oscillometric) blood pressures and heart rate measurements were obtained when the heart rate was low, using high sensitivity setting. Cardiac arrhythmias or hypotension prevented oscillometric measurements from being ...
Littlejohn A, Button C, Bowles F.Mean modal vectors of P1, P2 and QRS were determined in the 3 planes of a semi-orthogonal EKG lead system in 17 horses and ponies with chronic obstructive pulmonary disease (COPD) and in 17 clinically normal horses and ponies. Subjects were paired so that the heart rates of each pair were not dissimilar by more than 2 cycles per minute. Probably significant differences were observed between the mean angles of P1 vectors in the transverse and sagittal planes (T plane, normal = 324 degrees +/- 24,6 degrees, COPD = 342 degrees +/- 21,0 degrees, t = 2,0, P less than 0,05; S plane, normal = 331 deg...
Parks CM, Manohar M.Transmural distribution of myocardial blood flow and coronary vasodilator reserve (15-microns-diam radionuclide-labeled microspheres) was studied in 11 adult, healthy ponies at rest and during moderate and severe exercise performed on a treadmill (heart rate 56 +/- 4, 154 +/- 3, and 225 +/- 7 beats . min-1, respectively.). Exercise resulted in a marked increase in cardiac output, mean aortic pressure, right ventricular (RV) systolic and end-diastolic pressure, left ventricular (LV) end-diastolic pressure, and the maximum rate of rise of LV pressure LV (dP/dtmax). Accompanying these changes was...
Hartikka P, Dahlbom M, Westermarck H.In four training stables five trotter horses of the Finnish coldblooded breed and seven warmblooded trotters were treated with a ferrissaccharin preparation (Hippiron, Hausmann) intravenously. A short increase in heart frequency after the injection was noted. The cold solution injections, less than + 15 degrees C, may cause dangerous reactions. All horses showed an enhanced appetite, a substantially livier habitus after treatment.
Bayly WM, Gabel AA, Barr SA.Seven healthy, unexercised, previously trained, adult Standardbred horses were allotted to 2 groups and trained 78 days on a treadmill set at a 7 degree 30' angle. The groups were trained on different schedules, and the effects of training on heart rate, cardiac output, stroke volume, arteriovenous oxygen difference, systemic blood pressure, and venous lactic acid were determined. Measurements were made at rest, during exercise on the treadmill at rates of 55 m/min, 75 m/min, 100 m/min, and 154 m/min, and at 5 minutes after exercise (standardized exercise test). Heart rate and cardiac output d...
Westerling D.Thirteen experienced riders and three elite riders underwent bicycle ergometer tests at submaximal and maximal workloads. Oxygen uptake, pulmonary ventilation and heart rate were also studied during riding at a walk, a trot and a canter. The mean maximal oxygen uptake of the experienced riders in the ergometer test (2.71 . min-1) was superior to the average maximal oxygen uptake of other groups of the same age and sex. The average oxygen uptake of the experienced riders in trot sitting was 1.701 . min-1, trot rising 1.681 . min-1 and in canter 1.801 . min-1. The experienced riders used at leas...
Skarda RT, Muir WW.A new technique for producing segmental subarachnoid analgesia in adult horses without causing complete loss of locomotor control is described. A 17-gauge Huber point (Tuohy) needle was used to place a catheter with a stylet into the subarachnoid space at the lumbosacral intervertebral space in 13 adult horses (weighing 500 +/- 60 kg, representing both sexes) and to advance the catheter craniad to the thoracolumbar area. The position of the catheter was confirmed radiographically. A 2% mepivacaine hydrochloride solution (1.5 ml, 30 mg) was injected through the catheter at a rate of 0.5 ml/60 s...
Slinker BK, Campbell KB, Alexander JE, Klavano PA.The heart rate (HR) response to stepwise changes in mean arterial pressure (MAP) produced by methoxamine and sodium nitroprusside was studied in conscious horses, pigs, and calves. The respective steady-state arterial baroreflex sensitivities (delta HR/delta MAP expressed as beats min-1 . mm of Hg-1) were -1.20, -1.21, and -0.39 for decreasing MAP and -0.08, -0.91, and -0.56 for increasing MAP. After parasympathetic nervous system (PNS) blockade with atropine, the reflex sensitivity to decreasing MAP in horses and the pigs decreased to -0.62 and -0.65, respectively (P less than 0.05), whereas ...
Parry BW, Anderson GA, Gay CC.The hypotensive effect of acepromazine maleate was related to both the dose and route of administration. The degree and duration of hypotension varied between individual horses. In general, intravenous administration produced a more rapid maximum effect than intramuscular injection and the larger the dose the longer blood pressure remained at low levels. Average systolic pressure (of 6 horses) remained significantly below control values for more than 6 h after an intramuscular injection of 0.05 mg acepromazine maleate/kg body weight. Respiratory rate was markedly decreased, with the duration, ...
Morris DD, Fregin GF.Seventy-seven horses with atrial fibrillation (AF) were treated orally with quinidine sulfate (QS) at the University of Pennsylvania, School of Veterinary Medicine, Thirty-seven horses (48%) had adverse reactions to QS, the most common of which were nasal mucosal edema, anorexia, colic, and diarrhea. The mean highest daily QS dose was slightly greater in horses showing toxicity (P less than 0.1) and their conversion rate was less (P less than 0.05). A schedule of gradually increasing QS dose was time consuming, costly and not associated with fewer adverse reactions. Horses were compared by the...
Muir WW, Sams RA, Huffman RH, Noonan JS.The cardiopulmonary, behavioral, and pharmacokinetic properties of diazepam were determined in horses. Heart rate, cardiac output, mean pulmonary artery, aortic and right atrial blood pressures, respiratory rate, and arterial pH and blood gas values did not change after IV diazepam (0.05, 0.1, 0.2, 0.4 mg/kg) administration. Increasing doses of diazepam resulted in signs of muscle weakness including fixed stance, muscle fasciculations of the head, neck, and thorax muscles, ataxia, and then recumbency. Dosages of diazepam exceeding 0.2 mg/kg produced mild sedation. Behavioral changes persisted ...
Moore JN, Garner HE, Shapland JE, Roberts MC.The infusion (IV) of prostacyclin (PGI2) into conscious ponies resulted in systemic arterial hypotension and tachycardia. Mean systemic arterial pressure decreased from 103.3 mm of Hg to 88.5 mm of Hg when 125 ng of PGI2/kg/minute was infused, and heart rate increased from 55.0 to 102.0 beats/minute. When 208 ng of PGI2/kg/minute was infused, mean systemic arterial pressure decreased from 103.3 to 78.0 mm of Hg and heart rate increased from 55.0 to 109.3 beats/minute. There were no significant alterations in pulmonary arterial pressure, lactate, PCV, total WBC count, platelet count, serum lact...
Fregin GF.Eleven-lead electrocardiograms (ECGs) were recorded from 50 Thoroughbred (TB) and 50 Standard bred (SB) horses at rest with 40 tracings being selected from each group for more complete analysis. Incomplete atrioventricular block with dropped beats commonly reported in mature horses was recorded only in the TB (15%), while wandering of the atrial pacemaker (WAP) thought also to be associated with variations in tone of the autonomic nervous system was detected almost equally in both breeds (30%). In some horses (12.5%), the initial component of the P wave (P1) did not vary as seen with WAP but h...
Rose RJ.Blood counts and noradrenaline estimations were performed in 14 horses competing in a 160 km endurance ride. Samples were collected before the ride, immediately after the ride. 30 minutes after the ride and the day after the ride. For statistical analysis, a group of seven horses that completed the ride at a mean speed of 234 m/minute (fast group) was compared with seven horses that completed the ride at a mean speed of 144 m/minute (slow group). Immediately after the ride the fast group of horses had higher packed cell volume, haemoglobin, neutrophils and lower lymphocyte counts than the slow...
Kovár J.The possibility of using the test for pulse-rate response to gradated load in the evaluation of the endurance component of horse performance (in other words, response to the degree of horse adaptation to load) is discussed in detail. A mathematic-statistical analysis of regression coefficients is performed in the equations of the dependence of pulse rate on speed obtained in 278 three years old horses in the period following the termination of the basic training (145 Bohemian Warm-Blooded horses, 115 Kladrub Black horses and 18 English Half-Breds). A ten-score scale is calculated on the basis ...
Klug E, Deegen E, Lazarz B, Rojem I, Merkt M.Successful empirical treatment of 17 out of 24 stallions, which had failed to ejaculate after normal penile erection, intromission and friction, by chemical blockage of beta-receptors and additional stimulation of alpha-receptors led us to investigate stallions with normal ejaculatory patterns. In an initial experiment one adult half-bred stallion was injected with 4.88 mg noradrenaline hydrochloride (treatment A), 10 mg bunitrolol (treatment B = beta-receptor blockage) and a combination of treatment A and B. Investigations of the same stallion on dated occasions without treatment served as co...
Bottoms GD, Fessler JF, Roesel OF, Moore AB, Frauenfelder HC.A study was made of flunixin meglumine, an analgesic agent with antiinflammatory and antiprostaglandin activity, for the management of endotoxin-induced cardiovascular derangements. Three groups of 5 ponies each were used: controls--group 1; given endotoxin but not treated--group 2; and given endotoxin and treated with flunixin meglumine--group 3. Shock was induced in anesthetized ponies with IV injection of Escherichia coli endotoxin. Hemodynamic changes were monitored, and regional blood flow was determined at 4 different times, using microspheres labeled with 1 of 4 nuclides. There were ext...
Pedersoli WM, Ravis WR, Belmonte AA, McCullers RM.Digoxin (elixir, 0.022 mg/kg) was administered via stomach tube to healthy horses of mixed breeding and sexes. Serum digoxin concentrations reached a peak (2.21 +/- 0.6 ng/ml) at approximately 1 hour after dosing and had a half-life of 28.8 +/- 10.7 hours. Digoxin kinetics followed a triexponential curve, indicating that at least a 2 compartmental model is required to characterize the serum concentration-time curve after this route of administration. It was calculated that to achieve average serum concentrations of 1.1 ng/ml, an oral dose of 17.4 microgram of digoxin elixir/kg/day and an IV do...
Kovár J, Kostelecká B.On the basis of test results, regarding the pulse rate response to the increased load, obtained from 278 three-year-old horses after finishing their elementary training (145 Bohemian warm-blooded horses, 115 Kladrub Black horses and 18 English half-bred horses), a method was worked for the evaluation of their performance. As an evaluating criterion a velocity (v170) was chosen which was obtained from an experimentally determined regression dependence of velocity on the pulse rate at 170 pulses per minute. A set of v170 data were statistically processed and on the basis of quantiles of normal d...
Purohit RC, Mysinger PW, Redding RW.A continuous series of electroencephalograms (EEG) was obtained from each of 6 mature horses which had been given xylazine and ketamine hydrochloride IV. Electrocardiograms and respiratory rates were also obtained. The EEG of the unsedated standing adult horse displayed a dominant fast activity in the range of 25-35 Hz, 5-30 microV superimposed over slower 1-4 Hz, 10-50 microV activity with occasional 10-14 Hz, 10-40 microV spindle-type activity. The xylazine-sedated horse displayed hypersynchronous EEG patterns, with the dominant activity being 1-3 Hz, 10-70 microV with overlying mixed freque...
Thomas DP, Fregin GF.The purpose of this study was to measure cardiovascular, respiratory, and metabolic responses to graded treadmill exercise in the horse. A five-stage treadmill test up to 90% of predicted maximal heart rate was administered to five sedentary horses. The highest measured level of exercise produced a sixfold increase in cardiac output and a 41% elevation of stroke volume over standing values. Left ventricular, arterial, and right atrial pressures as well as the maximal time derivative of left ventricular pressure were all elevated during exercise. Under the same two conditions hematocrit (Hct) i...
Derksen FJ, Robinson NE, Stick JA.A surgical technique is described for preparation of chronic cervical vagal loops in ponies. Vagal blockade was induced by circulating methanol (-2 C) through coils which enclosed the loops. Vagal blockade increased tidal volume, heart rate, and systemic blood pressure and decreased respiratory rate. Atropine, given at a dose of 0.04 mg/kg IV, increased heart rate and systemic pressure but did not alter respiratory variables, indicating that vagal cooling caused both afferent and efferent blockade. The effects of vagal blockade were rapidly reversed when refrigerated coils were removed.
Farinelli F, de Rezende ASC, Fonseca MG, Lana ÂMQ, Leme FOP, Klein BON, Silva RHP, de Abreu AP, Damazio MJ, Melo MM.The Horse Agribusiness Complex is an important activity in the Brazilian agricultural sector. Mangalarga Marchador (MM) is the most numerous breed of horses in Brazil and its temperament and gait characteristics (4-beat stepping gait) allow for the constant growth of the breed and the performance of vs. equestrian activities. The training management currently adopted with MM horses is based on empiricism, and scientific support is necessary to improve the well-being of horses in competitions and maintain the physical integrity of these athletes. Therefore, this study aimed to verify the effect...
Youngblood CD, Hodgson DS, Beard WL, Song Y, Prakash P, Heflin LV.Recumbency affects respiratory mechanics and oxygenation in anesthetized horses. Changes in pleural and abdominal pressures that can impair ventilation have not been described in all recumbencies. The objective of this study was to determine the effects of patient positioning on transdiaphragmatic pressure and selected hemodynamic variables. Horses were maintained under total intravenous general anesthesia with nasal oxygen supplementation. Transnasal balloon catheters in the stomach and thoracic esophagus were used to measure intrathoracic and gastric pressures in standing horses and in anest...
Tzelos T, Blissitt KJ, Clutton RE.To determine whether preoperative electrocardiographic measurements linked to sympathetic nervous activity could be used to predict recovery quality after general anaesthesia in horses. Methods: Prospective, clinical study. Methods: Eighteen adult client-owned horses. Methods: The electrocardiogram (ECG) was recorded presurgery in horses under three standard conditions: stabled unattended; with a groom whilst being led along a standard course; alone in the induction box. After surgery, each animal's recovery quality was scored by eight experienced anaesthetists or technicians using Donaldson's...
Bellei MH, Kerr C, McGurrin MK, Kenney DG, Physick-Sheard P.To describe management of anesthesia for transvenous electrical cardioversion (TVEC) in horses and report perianesthetic complications. Methods: Retrospective case series. Methods: 62 horses with atrial fibrillation and without underlying cardiac disease and 60 horses without atrial fibrillation. Methods: Medical records of horses with atrial fibrillation anesthetized for TVEC were reviewed, as were records of horses without atrial fibrillation anesthetized for magnetic resonance imaging (MRI). The TVEC group horses were compared with MRI group horses for incidence of intraoperative bradycardi...
Vernemmen I, De Clercq D, Decloedt A, Schauvliege S, Taeymans Y, De Wolf D, van Loon G.This report describes a rare case of an aorto-cardiac fistula in a six-year-old French Warmblood mare presented with atrial fibrillation, decreased performance, ventral oedema, bounding arterial pulsation and pathological jugular venous pulse. A 2.7-cm-diameter fistula connected the right aortic sinus of Valsalva to the right atrium. Atrial fibrillation was likely due to volume overload of the right heart due to left-to-right shunting. The horse was treated by percutaneous transcatheter closure of the fistula delivered under general anaesthesia using a transarterial approach. The operation was...
Dyson DH, Pascoe PJ.A controlled study of the cardiovascular responses in horses anesthetized with acepromazine (0.05 mg/kg of body weight, IV), guaifenesin (100 mg/kg, IV), thiamylal (5.0 mg/kg, IV), and halothane in O2 (1.2 to 1.4% end-expired concentration) was performed to determine whether hypotension could be prevented by use of various treatments. Six horses were given 5 treatments in a randomized sequence: no treatment (control), methoxamine (0.04 mg/kg, IV), lactated Ringer solution (20.0 ml/kg, IV), 7.5% hypertonic saline solution (4.0 ml/kg, IV), or constant infusion of dobutamine (5.0 mg/kg/min, IV) d...
Leroux AA, Detilleux J, Sandersen CF, Borde L, Houben RM, Al Haidar A, Art T, Amory H.Risk factors for cardiac diseases in horses have not been explored in a large population of animals. Objective: To describe risk factors for various cardiac diseases in a hospital-based population of horses. Methods: Files of 3,434 horses admitted at the Internal Medicine Department of the Liege Equine Teaching Hospital between 1994 and 2011 were reviewed and of those, 284 were categorized as having moderate-to-severe cardiac disease. Methods: Observational study. After calculating prevalence for each cardiac disease, we tested whether breed (chi-square test) or sex, age, body weight (BW), and...
de Bruijn CM, Houterman W, Ploeg M, Ducro B, Boshuizen B, Goethals K, Verdegaal EL, Delesalle C.Most Friesian horses reach their anaerobic threshold during a standardized exercise test (SET) which requires lower intensity exercise than daily routine training. Objective: to study strengths and weaknesses of an alternative SET-protocol. Two different SETs (SETA and SETB) were applied during a 2 month training period of 9 young Friesian dressage horses. SETB alternated short episodes of canter with trot and walk, lacking long episodes of cantering, as applied in SETA. Following parameters were monitored: blood lactic acid (BLA) after cantering, average heart rate (HR) in trot and maximum H...
Recchi L, Alvariza S, Benech A, Ruiz N, José Estradé M, Suarez G, Crosignani N.The purpose of this study was to evaluate the pharmacokinetics of oral amitriptyline in horses. Oral amitriptyline (1 mg/kg) was administered to six horses. Blood samples were collected from jugular and lateral thoracic vein at predetermined times from 0 to 24 hr after administration. Plasma concentrations were determined by high-performance liquid chromatography and analyzed using noncompartmental methods. Pharmacodynamic parameters including heart rate, respiration rate, and intestinal motility were evaluated, and electrocardiographic examinations were performed in all subjects. The mean m...
O' Brien C, Pegg J.This observational study aimed to elucidate the effects of RWST on the cardiovascular and musculoskeletal systems of horses and concurrently determine whether RWST limits distal limb temperature increases previously reported during gallop training on land. A group of 15 clinically sound international event horses were recruited, and heart rate (HR), speed (km/h) and thermal images of the distal limb were analysed at set intervals during RWST training. Intervals of RWST produced a total mean HR value of 65.18 ± 3.76%, which is within the parameters for increased aerobic stamina. Mean HR increa...
Kokkonen UM, Hackzell M, Räsänen LA.To study the exercise-induced changes in atrial natriuretic peptide (ANP), a hormone with cardiovascular and renal effects, an incremental submaximal exercise test on a high-speed treadmill was carried out with Standardbred and Finnhorse trotters, the former bred for speed and the latter originally for heavy work. Standardbreds performed the 2 min exercise intervals at speeds of 6, 7, 8, 9 m s-1 and Finnhorses, according to their training status, at 5, 6, 7, 8 m s-1, 4, 5, 6, 7 m s-1 or 5, 6, 7 m s-1. Steady-state heart rate (HR) was reached within each 2 min interval. The increase in HR was l...
Seino KK, Foreman JH, Greene SA, Goetz TE, Benson GJ.Capsaicin is a local substance P depleter with dramatic analgesic effects. We tested the hypothesis that the topical application of capsaicin ointment over the palmar digital nerves would attenuate the clinical effects of a reversible model of equine foot lameness. Seven healthy adult horses shod unilaterally with adjustable heart bar shoes were studied in a crossover design for 2 weeks. Grade 5.0/5.0 lameness (nonweight bearing) was induced by tightening the adjustable heart bar shoe. One hour later, capsaicin ointment was applied over the medial and lateral palmar digital nerves 3 cm proxima...
Bayly WM, Slocombe RF, Schott HC, Hines MT, Sides RH, Hakala JE.The possibility that pre-exercise inhalation of a bronchodilator by healthy horses could improve their mechanics of breathing and enhance performance was investigated. Ipratropium bromide (0.35 microg/kg bwt; n = 7) was administered by nebulisation 30 min before exercise and frusemide (1 mg/kg bwt; n = 6) was given in the same manner 2 h before exercise. Albuterol sulphate (360 and 720 microg; n = 7) were administered with a metered dose inhaler 2 h before exercise. Each drug was investigated independently of the others using cross-over protocols. Horses completed incremental exercise tests an...
Nannarone S, Cenani A, Gialletti R, Pepe M.To compare, in horses undergoing laparotomy for colic, the effects of administering or not administering a loading intravenous (IV) bolus of lidocaine prior to its constant rate infusion (CRI). Effects investigated during isoflurane anaesthesia were end-tidal isoflurane concentration (Fe'ISO), cardiovascular function, anaesthetic stability and the quality of recovery. Methods: Prospective, randomized clinical study. Methods: Thirty-six client-owned horses. Methods: Horses were assigned randomly to receive lidocaine as a CRI (50 μg kg(-1) minute(-1) ) either preceded (LB) or not preceded (L...
Seeherman HJ, Morris EA.The purpose of this study was to compare exercise measurements in yearling, two-year-old and adult Thoroughbreds using a standardised treadmill incremental exercise test. Peak oxygen consumption (VO2 peak: 128.0 +/- 2.1, 140.0 +/- 2.1, 163.7 +/- 3.4; ml/kg/min +/- se, P less than 0.05), peak packed cell volume (PCV peak: 0.50 +/- 0.01, 0.58 +/- 0.01, 0.64 +/- 0.01 litres/litre +/- se, P less than 0.05) and the maximum number of steps completed in the exercise test (STEPmax: 7.7 +/- 0.1, 8.1 +/- 0.1, 8.6 +/- 0.1; steps +/- se, P less than 0.05) increased with age and degree of physical activity...
Clark-Price SC, Lascola KM, Auckburally A, Boone LH, Caldwell FJ, Weatherall KM, Hanson RR.Impairment of oxygen uptake can occur during general anesthesia in horses resulting in hypoxemia. Multiple treatments have been investigated for correction of hypoxemia with varying levels of success. In clinical trials, albuterol, a short-acting β2 adrenergic agonist, improved arterial oxygen partial pressure (PaO2) in anesthetized horses unresponsive to adjustments in mechanical ventilation and administration of positive inotropic drugs. However, controlled studies comparing the magnitude of change and duration of effect of albuterol on PaO2 in healthy, nonhypoxemic anesthetized horses are ...
Borer KE, Clarke KW.To determine whether hyoscine has a sparing effect on the volume of dobutamine required to maintain mean arterial pressure (MAP) at 70 mmHg in horses anaesthetized with halothane. Methods: Prospective, randomized, controlled clinical trial. Methods: Twenty adult horses weighing 507 +/- 97 kg (mean +/- SD), aged 10 +/- 5 years. Methods: Pre-anaesthetic medication in all horses was intramuscular (IM) acepromazine (40 mug kg(-1)) and intravenous (IV) detomidine (0.02 mg kg(-1)). Anaesthesia was induced with ketamine (2.2 mg kg(-1) IV) and diazepam (0.02 mg kg(-1) IV), and maintained with halothan...
Kavazis AN, Kivipelto J, Choe HS, Colahan PT, Ott EA.The objective of this study was to investigate the effects of ribose supplementation on blood ammonia-N, plasma lactic acid, plasma glucose, volume of oxygen consumption (VO2), heart rate, and performance in Thoroughbred geldings performing a maximal treadmill standardized exercise test (SET). The hypothesis tested was that ribose supplementation would decrease ammonia-N and lactic acid accumulation during exercise, and improve performance. Eight Thoroughbred geldings were assigned randomly to one of two groups: glucose or ribose. The glucose group received 0.15 g glucose/kg of BW, and the rib...
Jacquay ET, Harris PA, Adams AA.Transportation of horses on short journeys can lead to an increase in stress. There are known age-associated changes in immune and metabolic responses in horses; however, no research exists evaluating how age may influence these responses to transportation stress. Eleven mares within two age groups, aged (n = 5, 22 ± 1 year) or young (n = 6, 2 ± 1 year), were transported 1 hour and 20 minutes. Peripheral blood and saliva were collected before and after transportation at baseline (2 to 3 weeks prior to transportation), 24 hours pre-transport, 1 hour before loading, 15 minutes, 30 minutes,...
Soiluva J, Häyrinen L, Gangini G, Öistämö R, Gracia-Calvo LA, Raekallio MR.Traditional visual lameness assessment is subjective. Ethograms have been developed for evaluating pain and objective sensors to detect lameness. Heart rate (HR) and heart rate variability (HRV) have been used to evaluate stress and pain. The aim of our study was to compare subjective and behavioral lameness scores, a sensor system measuring movement asymmetry, HR, and HRV. We hypothesized that these measures would show related trends. In 30 horses, an inertial sensor system was used to measure movement asymmetries during trot in-hand. A horse was categorized as sound if each asymmetry was les...
Trösch M, Cuzol F, Parias C, Calandreau L, Nowak R, Lansade L.Over the last few years, an increasing number of studies have aimed to gain more insight into the field of animal emotions. In particular, it is of interest to determine whether animals can cross-modally categorize the emotions of others. For domestic animals that share a close relationship with humans, we might wonder whether this cross-modal recognition of emotions extends to humans, as well. In this study, we tested whether horses could recognize human emotions and attribute the emotional valence of visual (facial expression) and vocal (non-verbal vocalization) stimuli to the same perceptua...
Schwarzwald CC, Bonagura JD, Luis-Fuentes V.Quinidine is effective for treatment of atrial fibrillation (AF) in horses, but often accelerates ventricular response rate. Diltiazem effectively controls heart rate response to AF in other species. This investigation determined the effects of diltiazem on cardiac rate and rhythm, left ventricular (LV) function, central hemodynamics, and peripheral blood flow in normal, standing, nonsedated horses. A dose-finding study was performed. Afterward, 8 healthy horses were treated with diltiazem IV every 30 minutes to achieve cumulative dosages of 0 (saline control), 1, 1.5, and 2 mg/kg. Plasma dilt...
Hellyer PW, Dodam JR, Light GS.Dynamic baroreflex sensitivity for increasing arterial pressure (DBSI) was used to quantitatively assess the effects of anesthesia on the heart rate/arterial pressure relationship during rapid (less than or equal to 2 minutes) pressure changes in the horse. Anesthesia was induced with IV administration of xylazine and ketamine and maintained with halothane at a constant end-tidal concentration of 1.1 to 1.2% (1.25 to 1.3 minimal alveolar concentration). Systolic arterial pressure (SAP) was increased a minimum of 30 mm of Hg in response to an IV bolus injection of phenylephrine HCl. Linear regr...
Skarda RT, Muir WW.To determine effects of i.v. administered yohimbine on perineal analgesia, cardiovascular and respiratory activity, and head and pelvic limb position in healthy mares following epidural administration of detomidine hydrochloride solution. Methods: 8 healthy mares. Methods: Each mare received detomidine hydrochloride (0.06 mg/kg of body weight), administered in the caudal epidural space, followed 61 minutes later by yohimbine (0.05 mg/kg; test) or sterile saline (0.9% NaCl) solution (control), administered i.v., in a randomized, crossover study design with > or = 2 weeks between treatments. ...
Wiśniewska A, Janczarek I, Tkaczyk E, Wilk I, Janicka W, Próchniak T, Kaczmarek B, Pokora E, Łuszczyński J.This study aimed to perform a comparative analysis of the horses' heart rate parameters and locomotor activity in a herd or isolation, with or without the company of goats. Twenty horses were tested in a paddock, accompanied (or not) by three goats. The experiment comprised four tests (a control test of a herd of horses without goats, a horse isolation test without goats, a test of a herd of horses with goats and a test of an isolated horse with goats). The horse's locomotor behavior, and the HR, RR, rMSSD, LF, HF, and LF/HF were recorded. The data analysis included a 15-min rest, procedural a...
Hesselkilde EZ, Carstensen H, Flethøj M, Fenner M, Kruse DD, Sattler SM, Tfelt-Hansen J, Pehrson S, Braunstein TH, Carlson J, Platonov PG....Large animal models are important in atrial fibrillation (AF) research, as they can be used to study the pathophysiology of AF and new therapeutic approaches. Unlike other animal models, horses spontaneously develop AF and could therefore serve as a bona fide model in AF research. We therefore aimed to study the electrical, functional and structural remodelling caused by chronic AF in a horse model. Nine female horses were included in the study, with six horses tachypaced into self-sustained AF and three that served as a time-matched sham-operated control group. Acceleration in atrial fibrilla...
De Mello Costa MF, Anderson GA, Davies HM, El-Hage CM, Slocombe RF.Investigate angiotensin converting enzyme (ACE) activity in equine plasma as a predictor of performance in endurance competitions and the effect of endurance exercise on ACE activity. Objective: Precompetition values of ACE activity in equine blood are correlated with performance results and with heart rates pre- and post competition used as indicators of fitness. Endurance exercise increases ACE activity. Methods: Nineteen horses participating in an 80 km endurance competition had venous blood samples collected before and after the ride. ACE activity and total protein were measured in the blo...
Van Dijk P, Lankveld D, Rijkenhuizen A, Jonker FH.To assess the hormonal, metabolic and physiological effects of laparascopic surgery performed under a sedative analgesic combination of detomidine and buprenorphine in standing horses. Methods: Prospective study. Methods: Eight healthy adult Dutch Warmblood horses and five healthy adult ponies undergoing laparoscopy were studied. Five healthy adult horses not undergoing laparoscopy were used as a control group. Methods: The sedative effect of an initial detomidine and buprenorphine injection was maintained using a continuous infusion of detomidine alone. The heart and respiratory rate, arteria...
Fenner K, Yoon S, White P, Starling M, McGreevy P.Restrictive nosebands are common in equestrian sport. This is concerning, as recent evidence suggests that very tight nosebands can cause a physiological stress response, and may compromise welfare. The objective of the current study was to investigate relationships that noseband tightness has with oral behavior and with physiological changes that indicate a stress response, such as increases in eye temperature (measured with infrared thermography) and heart rate and decreases in heart rate variability (HRV). Horses (n = 12) wearing a double bridle and crank noseband, as is common in dressage ...
Southwood LL, Gassert T, Lindborg S.It is the impression of some surgeons that geriatric horses have a lower survival rate compared to mature nongeriatric horses following colic surgery. One possible reason for this is that geriatric horses may be more critically ill at admission and have more severe disease than mature nongeriatric horses. Objective: To compare admission historical, physical examination and laboratory data for geriatric and mature nongeriatric horses referred for signs of colic. Methods: Medical records of horses admitted with a presenting complaint of colic between 2000 and 2006 were reviewed. Geriatric horses...
