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Topic:Heart Rate

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.
[The P-wave in the EKG of healthy horses].
Berliner und Munchener tierarztliche Wochenschrift    September 15, 1979   Volume 92, Issue 18 349-352 
Grauerholz H.No abstract available
The actions of the beta-adrenoceptor blocking agents propranolol and metoprolol in the maximally exercised horse.
Research in veterinary science    July 1, 1979   Volume 27, Issue 1 22-29 
Snow DH, Summers RJ, Guy PS.The effects of two beta-adrenoceptor antagonists, propranolol (0.2 mg/kg) and metoprolol (0.2 mg/kg) on some physiological and metabolic changes produced by maximal exercise in the horse were investigated. Both drugs reduced the elevation in heart rate seen immediately following exercise and reduced performance as was seen by the increased time taken to perform each gallop. The rise in plasma glucose, glycerol and lactate, and the fall in blood pH seen following exercise were attenuated by both drugs. However, a greater increase in plasma free fatty acids occurred. Exercise produced a nine- to...
Electrocardiography, heart scope and haematology of horses competing in an endurance ride.
Australian veterinary journal    June 1, 1979   Volume 55, Issue 6 247-250 
Rose RJ, Ilkiw JE, Hodgson D.Thirty-one horses competing in a 100 kilometre endurance ride had electrocardiograms recorded before and after the ride from which the heart score of each horse was calculated. Blood was also taken to determine the packed cell volume (PCV) and total plasma protein (TPP) before the ride, after 60 kilometres (mid ride) and at completion of the ride. Statistical analysis of the heart scores showed that a faster group of horses had significantly higher heart scores than either a slower group or those eliminated due to inadequate recovery of heart rate. No horses developed electrocardiogram abnorma...
Electrocardiography, Heart Score, and Hematology of Horses Competing in an Endurance Ride.
Australian veterinary journal    May 1, 1979   Volume 55, Issue 5 247-250 doi: 10.1111/j.1751-0813.1979.tb00389.x
Rose RJ, Ilkiw JE, Hodgson D.Thirty-one horses competing in a 100 kilometre endurance ride had electrocardiograms recorded before and after the ride from which the heart score of each horse was calculated. Blood was also taken to determine the packed cell volume (PCV) and total plasma protein (TPP) before the ride, after 60 kilometres (mid-ride) and at completion of the ride. Statistical analysis of the heart scores showed that a faster group of horses had significantly higher heart scores than either a slower group or those eliminated due to inadequate recovery of heart rate. No horses developed electrocardiogram abnorma...
[Effects of exercise and training on the heart and circulation in horses (author’s transl)].
DTW. Deutsche tierarztliche Wochenschrift    January 5, 1979   Volume 86, Issue 1 2-7 
von Engelhardt W.No abstract available
Blood-gas, acid-base and haematological values in horses during an endurance ride.
Equine veterinary journal    January 1, 1979   Volume 11, Issue 1 56-59 doi: 10.1111/j.2042-3306.1979.tb01300.x
Rose RJ, Ilkiw JE, Martin IC.The effects of prolonged strenuous exercise on arterial and venous oxygen tension, carbon dioxide tension, pH, bicarbonate, standard bicarbonate, base excess, haemoglobin, packed cell volume and total plasma protein were studied in 36 horses during a 100 km endurance ride. There were significant changes in many parameters when pre-ride values were compared with both mid-ride and end of ride values. The prominent changes were the development of dehydration and a metabolic alkalosis. At the mid-ride sampling time those horses with higher heart rates had a greater degree of metabolic alkalosis th...
Myocardial perfusion and function during acute right ventricular systolic hypertension.
The American journal of physiology    December 1, 1978   Volume 235, Issue 6 H628-H636 doi: 10.1152/ajpheart.1978.235.6.H628
Manohar M, Bisgard GE, Bullard V, Will JA, Anderson D, Rankin JH.Hemodynamics, myocardial function, and regional myocardial blood flow (MBF) were measured in 6 closed-chest ponies anesthetized with ketamine hydrochloride before (control) and after creation of acute right ventricular systolic hypertension (RVSH) during normoxia and isocapnic hypoxia. The right ventricular (RV) systolic pressure during each RVSH approached 90 mmHg. There were significant alterations in the pattern of total ventricular MBG distribution in favor of the RV. Because RV myocardium received proportionate increments to its endocardium as well as epicardium, it is concluded that auto...
Haemodynamics in the horse: 2. Intracardiac, pulmonary arterial and aortic pressures.
Equine veterinary journal    October 1, 1978   Volume 10, Issue 4 207-215 doi: 10.1111/j.2042-3306.1978.tb02263.x
Brown CM, Holmes JR.The paper reports the changing pressure values during the cardiac cycle recorded from various chambers of the heart and great vessels using 2 catheter-mounted transducers, 9 cm apart. Pulse pressures are calculated. Transvalval pressure differences are determined taking account of the effect of hydrostatic pressure between the 2 sensors. The effects of some valvular lesions and arrhythmias and of changes in intrathoracic pressure are also described.
Haemodynamics in the horse: 3. Duration of the phases of the cardiac cycle.
Equine veterinary journal    October 1, 1978   Volume 10, Issue 4 216-223 doi: 10.1111/j.2042-3306.1978.tb02265.x
Brown CM, Holmes JR.The paper reports observations on the duration of various phases of the cardiac cycle using a bipole ECG record as a time base from which to measure the timing of pressure changes in the chambers of the heart and great vessels. From the findings the likely sequence of mechanical events during the cardiac cycle in the atria and ventricles is described.
Heart rate during a defined exercise test in horses with heart and lung diseases.
Equine veterinary journal    October 1, 1978   Volume 10, Issue 4 235-242 doi: 10.1111/j.2042-3306.1978.tb02269.x
Maier-Bock H, Ehrlein HJ.During a gradually increasing exercise test heart rates were determined in healthy animals and in 2 groups of sick horse. These included 31 animals with a chronic pulmonary disorder and 5 with chronic heart disease. The alteration in heart rate was correlated with the clinical signs exhibited. In the horses with lung disease there was a close correlation between the stage of the diseases and the heart rate during the exercise test. In 3 animals with heart valve disease there was no apparent difference in heart rate compared with healthy horses. On the other hand the exercising heart rate of ho...
Cardiopulmonary effects of narcotic agonists and a partial agonist in horses.
American journal of veterinary research    October 1, 1978   Volume 39, Issue 10 1632-1635 
Muir WW, Skarda RT, Sheehan WC.The cardiopulmonary effects of the narcotic agonists morphine, meperidine, oxymorphone, and methadone and of the partial agonist pentazocine were examined in the pain-free adult horse. The drugs produced dysphoric followed by euphoric effects. Increases in heart rate, arterial blood pressure, and cardiac output were observed in all horses with all drugs. Arterial blood pressure remained increased even after heart rate and cardiac output had returned to base-line values. Respiratory rate generally remained unchanged or increased shortly after drug administration and then decreased insignificant...
Energy under-nutrition in the weanling filly foal. III. Effects on heart rate and subsequent voluntary food intake.
The British veterinary journal    July 1, 1978   Volume 134, Issue 4 333-341 doi: 10.1016/s0007-1935(17)33435-8
Ellis RN, Lawrence TL.In two separate experiments food intakes and heart rates were monitored in New Forest and Welsh filly foals maintained at constant weight (by energy restriction) or allowed to grow normally for 180 (New Forest) or 147 (Welsh) days. Subsequent to these periods voluntary food intakes from feeding the same diet for 107 days (New Forest ponies) and herbage dry matter intakes from allowing free access to pasture for 42 days (Welsh ponies) were recorded. In the ponies maintained at constant live-weight food intakes and heart rates declined to reach and remain at new low levels. Herbage dry matter co...
Cardiovascular, acid-base, electrolyte, and plasma volume changes in ponies developing alimentary laminitis.
American journal of veterinary research    May 1, 1978   Volume 39, Issue 5 741-744 
Harkema JR, Robinson NE, Scott JB.Twelve Shetland ponies were fed a high-starch ration. Seven ponies which had a transitory metabolic acidosis developed laminitis 56 hours (+/- 3.5, SEM) after overfeeding. These ponies also developed persistent hypokalemia, hyperthermia, and increased heart rate 24 hours before the onset of lameness. Serum sodium, serum chloride, hematocrit, plasma volume, and blood volume were unchanged. At the onset of clinical signs of laminitis, cardiac output and blood pressure increased, but total peripheral resistance was unchanged. None of the measured or calculated values predicted the onset of lamini...
A phonocardiographic study of equine heart sounds.
Australian veterinary journal    April 1, 1978   Volume 54, Issue 4 161-170 doi: 10.1111/j.1751-0813.1978.tb02439.x
Vanselow B, McCarthy M, Gay CC.The occurrence and timing of heart sounds were examined from phonocardiograms taken from the mitral, aortic and tricupsid recording areas in each of 18 horses. 10 sound events could be identified with each cardiac cycle. Atrial contraction produced up to 3 sound events. The first heart sound consisted of 4 components whereas the second sound was single. Two sound events were associated with the 3rd heart sound in early diastole. The occurrence of third and fourth heart sound components varied between horses and between recording areas. The mitral recording area was considered most satisfactory...
Cardiovascular effects of halothane in the horse.
American journal of veterinary research    April 1, 1978   Volume 39, Issue 4 611-615 
Steffey EP, Howland D.Cardiovascular effects of venous alveolar concentrations of halothane in oxygen were studied in 8 young, healthy horses under conditions of constant arterial carbon dioxide tension. The alveolar concentration of halothane was expressed as a multiple of the minimal alveolar concentration (MAC) which was known for each animal. Increasing alveolar halothane concentrations to MAC 2.0 resulted in a progressive and significant (P less than 0.05) decline in systemic arterial pressure and left ventricular work. Cardiac output decreased between MAC 1.0 and MAC 2.0 as a result of a significant (P less t...
Effect of exercise on systemic blood pressure and heart rate in horses.
Pflugers Archiv : European journal of physiology    November 25, 1977   Volume 372, Issue 1 95-99 doi: 10.1007/BF00582212
Hörnicke H, von Engelhardt W, Ehrlein HJ.Carotid loops were prepared in 3 horses several months prior to the experiments. Systemic blood pressure was recorded at rest and during exercise by insertion of a plastic cannula into the carotid artery. The pressure transducer was fixed at the neck of the animal. The blood pressure signal was transmitted by telemetry. When the horses were standing under the rider, the following results were obtained: heart rate 38 +/- 5 beats-min-1, systolic pressure 115 +/- 15, disstolic pressure 83 +/- 10, mean pressure 97 +/- 12, and pulse pressure 32 +/- 9 mm Hg. During steady gallop at a mean speed of 5...
Paroxysmal atrial fibrillation in a racehorse.
Australian veterinary journal    November 1, 1977   Volume 53, Issue 11 545-549 doi: 10.1111/j.1751-0813.1977.tb07943.x
Rose RJ, Davis PE.A 4-year-old thoroughbred stallion with a history of loss of racing form was studied over a period of approximately 7 months. At the initial examination he showed positive T waves in 1 chest lead and wandering of the pacemaker. This was followed by an episode of paroxysmal atrial fibrillation which disappeared spontaneously and was replaced by significant T wave changes in all the chest leads. During a period when these changes persisted, there was progressive lengthening of the P wave and the P-R interval. Because the last ECG showed evidence of intra-atrial block, first degree A-V block and ...
Pacing techniques in assessing cardiac function in the horse.
Equine veterinary journal    October 1, 1977   Volume 9, Issue 4 178-180 doi: 10.1111/j.2042-3306.1977.tb04021.x
O'Callaghan MW.The problem of transitory cardiac arrhythmias in equidae is discussed particularly with regard to the referral of suspect cases to specialist institutions for second opinion. Recently developed electro-stimulation techniques designed to uncover problem arrythmias, are briefly described and their potential in the analysis of cardiac electrical function under varying conditions is reviewed. The author cautions on the too rapid evaluation of the techniques for this purpose while remaining optimistic of the potential of electro-stimulation in the objective analysis of cardiac electric parameters.
An evaluation of chemical restraining agents in the horse.
The Veterinary record    July 9, 1977   Volume 101, Issue 2 30-33 doi: 10.1136/vr.101.2.30
MacKenzie G, Snow DH.An evaluation of acepromazine (0.5 mg/kg intramuscularly), azaperone (0.7 and 0.9 mg/kg intramuscularly) and xylazine (2.0 mg/kg intramuscularly) as chemical restraining agents was carried out in seven horses. (Xylazine and azaperone were used at the recommended dose rates; acepromazine at five times the recommended dose rates). Of the three drugs administered only azaperone produced sufficient sedation in all the horses to allow a percutaneous needle muscle biopsy to be taken from six muscles. With acepromazine and xylazine this procedure could be successfully carried out in five and four hor...
Physiologic responses of the horse to a hot, arid environment.
American journal of veterinary research    July 1, 1977   Volume 38, Issue 7 1041-1043 
Honstein RN, Monty DE.Field investigations were conducted under natural environmental conditions to determine the physiologic responses of rested, hydrated horses (Equus caballus) to the very hot, dry weather characteristic of the summer season in southern Arizona. The emphasis of the investigation was placed on those thermoregulatory mechanisms which are involved in the maintenance of homoiothermy. Rectal temperature of the horses studied remained relatively stable throughout the day, during both cool and hot weather seasons. However, when horses were exposed to hot summer temperatures, rectal temperature (heat st...
Plasma biochemistry alterations in horses during an endurance ride.
Equine veterinary journal    July 1, 1977   Volume 9, Issue 3 122-126 doi: 10.1111/j.2042-3306.1977.tb04002.x
Rose RJ, Purdue RA, Hensley W.The effects of prolonged strenous exercise on the plasma concentrations of sodium, potassium, calcium, chloride, bicarbonate, phosphate, albumin, cholesterol, glucose, creatinine, bilirubin, alkaline phosphatase, creatine phosphokinase, lactic dehydrogenase and asparate amino transferase were studied in a group of 26 horses competing in an endurance ride. There were significant changes in most parameters, when control values were compared with those taken immediately after the ride. There was also a significant correlation between several biochemical parameters and heart rate taken 30 minutes ...
Cardiac output, left ventricular ejection rate, plasma volume, and heart rate changes in equine laminitis-hypertension.
American journal of veterinary research    June 1, 1977   Volume 38, Issue 6 725-729 
Garner HE, Hahn AW, Salem C, Coffman JR, Hutcheson DP, Johnson JH.Acute laminitis-hypertension was produced experimentally by carbohydrate overloading of the gastrointestinal tract in 8 horses, and the resulting hemodynamic changes were measured. Statistically significant (P less than 0.01) increases in cardiac output, left ventricular ejection rate, heart rate, and arterial pressure were related to statistically nonsignificant changes in peripheral resistance and a delayed (Obel grade 3 plus 24 hours) decrease in plasma volume. When compared with control values, the doubling of cardiac output and left ventricular ejection rate simultaneous with little or no...
Left ventricular systole in conscious and anesthetized horses.
American journal of veterinary research    May 1, 1977   Volume 38, Issue 5 675-680 
Hillidge CJ, Lees P.No abstract available
Biochemical and physiological effects of catecholamine administration in the horse.
Research in veterinary science    May 1, 1977   Volume 22, Issue 3 357-360 
Anderson MG, Aitken MM.Adrenaline was given intramuscularly to resting horses. It increased heart rate, sweating, blood levels of lactic dehydrogenase, aldolase, creatine kinase, glucose, lactate, free fatty acids and glycerol. Responses to isoprenaline, to noradenaline and to adrenaline after pretreatment with propranolol indicated that beta receptors were involved in stimulation of tachycardia, sweating, lipolysis and muscle glycogenolysis, and alpha receptors in stimulation of liver glycogenolysis and leakage of intracellular enzymes. The time course and relative magnitude of the effects on different enzymes was ...
Echocardiography in the horse.
Journal of the American Veterinary Medical Association    April 15, 1977   Volume 170, Issue 8 815-819 
Pipers FS, Hamlin RL.Echocardiograms were obtained from 25 standing, clinically normal horses, using an ultrasonic recording device. The echobeam penetrated the right thoracic wall in the area of the 4th to 5th intercostal space, with a frequency of 2.5 mHz. Measurements of left ventricular wall thickness generated a mean value of 3.2 +/- 0.18 (SEM)cm, whereas the left ventricular chamber diameter in diastole was 9.3 +/- 0.30 cm and in systole was 5.7 +/- 0.23 cm. The aortic root dimensions had a mean of 7.7 cm, with a SEM of 0.16. Mitral valve closing slope (E-F) was calculated to be 17.7 +/- 0.87 mm/second, and ...
Exercise studies in horses: 1. A simple telemetry system for recording excercise ECGs in horses.
Equine veterinary journal    April 1, 1977   Volume 9, Issue 2 72-74 doi: 10.1111/j.2042-3306.1977.tb03984.x
Hill G, Atkins R, Littlejohn A, Kruger JM, Bowles F.A robust low cost portable radiotelemetry system is described for the horse and its method of operation and advantages briefly discussed. The equipment consisted of 2 electrodes forming a bipolar lead, a transmitter, a receiver and a writing device. The sitting, application and immobilising of the electrodes was a most important factor in obtaining good quality recordings. ECGs were recorded at all paces and also while jumping and the results proved satisfactory.
Treatment of atrial fibrillation in three racehorses.
Equine veterinary journal    April 1, 1977   Volume 9, Issue 2 68-71 doi: 10.1111/j.2042-3306.1977.tb03982.x
Rose RJ, Davis PE.Three young Standardbred pacers with atrial fibrillation were treated with quinidine sulphate (QS) by stomach tube. They were given 10g QS every 2 hours until cardioversion was achieved. Total doses varied between 20 and 30 g. No premedication was given nor any follow up treatment after return to sinus rhythm. All horses were given 3 months rest after the treatment, and when electrocardiographed then, and at 6 months, showed normal sinus rhythm. As all 3 horses won races after cardioversion and showed subsequent normal electrocardiograms it seems likely that atrial fibrillation can occur witho...
Exercise studies in horses: 2. The cardiac response to exercise in normal horses and in horses with chronic obstructive pulmonary disease.
Equine veterinary journal    April 1, 1977   Volume 9, Issue 2 75-83 doi: 10.1111/j.2042-3306.1977.tb03986.x
Littlejohn A, Kruger JM, Bowles F.The relationship of velocity (v) to heart rate (HR)and of kinetic energy (KE) to heart rate, were investigated in 6 normal horses and in 6 horses with chronic obstructive pulmonary, disease (COPD). Radiotelemetry was used to determine the heart rate while subjects were ridden on a 400m track. Velocity was measured by stop-watch between 2 markers 50 m apart at the end of the track. Kinetic energy was calculated from the formula KE =1/2 Mv2, where M = mass of horse, rider, saddle and bridle (KG) and V = velocity (metres per second). In all subjects, the relationship of velocity to heart rate was...
Hemodynamics and myocardial function during acute hypoxia in the pony.
American journal of veterinary research    March 1, 1977   Volume 38, Issue 3 365-371 
Buss DD, Bisgard GE.Hemodynamics and myocardial contractility were evaluated in 6 unanesthetized ponies during hypocapnic and isocapnic hypoxia and during hypocapnic hypoxia after beta adrenergic blockade with propranolol. Hypocapnic hypoxia, with a mean arterial oxygen pressure (PaO2) of 41.9 mm of Hg, produced a decrease in stroke index and an increase in heart rate, with no change of cardiac index. A moderate increase in left ventricular contractility occurred during hypocapnic hypoxia. Beta adrenergic blockade abolished changes in nearly all indices of left ventricular contractility during hypocapnic hypoxia,...
Cardiovascular effects of exercise and training in horses.
Advances in veterinary science and comparative medicine    January 1, 1977   Volume 21 173-205 
von Engelhardt W.No abstract available