Computerized ECG recording in horses during a standardized exercise test.

In the horse, it is important to make a reliable ECG recording during exercise as cardiac arrhythmia is one of the possible causes of poor performance. The purpose of the present study was to obtain a satisfactory, standardized method for ECG recording by computer during a standardized treadmill exercise test and to evaluate the procedure both in healthy and in diseased horses. Ten experienced healthy research horses were used to develop and adapt the original method (for humans) of computerized ECG recording with the Cardio Perfect software program and to obtain reference values for heart rate and blood variables. Further, three diseased horses (patients) were examined to evaluate whether the test procedures were also usable for horses without extensive experience in treadmill and other experimental procedures. During a standardized exercise test on a treadmill at walk (1.7 m/s), trot (4.0 m/s), and canter (7.0 m/s at 0% and 4% treadmill inclination), the ECG was recorded using two bipolar leads (from xiphoid to manubrium respectively to the left withers) and one unipolar lead (on the left ventral thorax). The quality of the exercise ECGs was satisfactory. The heart rate was detectable and arrhythmias were identifiable. Most research horses did not show arrhythmias during exercise, except a single atrial premature complex (APC). The reference values for the mean heart rate for the different stages of the exercise test differed from 84 + or - 7 to 176 + or - 21 beats per minute (bpm). The exercise test provoked in healthy horses a plasma lactate concentration around the anaerobic threshold. Most patients were also able to finish the test. In conclusion, the developed method to obtain an exercise ECG during a standardized exercise test proved to be reliable and applicable both in research horses and in patients, thus extending the possibilities to diagnose arrhythmias.

[1]  Littledike Et,et al.  Electrocardiographic changes in induced hyperkalemia in ponies. , 1982 .

[2]  Fregin Gf.  The equine electrocardiogram with standardized body and limb positions. , 1982 .

[3]  R. Rose,et al.  The use of electrocardiography in the diagnosis of poor racing performance in the horse. , 1978, Australian veterinary journal.

[4]  E. Deegen,et al.  Behaviour of the heart rate of horses with auricular fibrillation during exercise and after treatment. , 1976, Equine veterinary journal.

[5]  G. A. Stewart,et al.  Cardiac monitoring during exercise tests in the horse. 3. Changes in the electrocardiogram during and after exercise. , 1976, Australian veterinary journal.

[6]  M M Sloet van Oldruitenborgh-Oosterbaan,et al.  The accuracy of three different heart rate meters used for studies in the exercising horse. , 1988, Zentralblatt fur Veterinarmedizin. Reihe A.

[7]  J. Stewart,et al.  Effects of clenbuterol hydrochloride on certain respiratory and cardiovascular parameters in horses performing treadmill exercise. , 1983, Research in veterinary science.

[8]  C. Irvine.  STUDIES ON THE ELECTROCARDIOGRAM OF THE RACEHORSE , 1963 .

[9]  J. Holmes,et al.  ECG recording at rest and during exercise in the horse , 1990 .

[10]  J. Steel,et al.  Cardiac monitoring during exercise tests in the horse. 1. Magnetic tape recording in preference to radio-telemetry. , 1975, Australian veterinary journal.

[11]  H. Ehrlein,et al.  Heart rate during a defined exercise test in horses with heart and lung diseases. , 1978, Equine veterinary journal.

[12]  Marja Raekallio,et al.  Long Term ECG Recording with Hotter Monitoring in Clinically Healthy Horses , 1992, Acta Veterinaria Scandinavica.

[13]  D L Evans,et al.  Method of investigation of the accuracy of four digitally-displaying heart rate meters suitable for use in the exercising horse. , 1986, Equine veterinary journal.

[14]  H. Seeherman,et al.  Clinical evaluation of poor performance in the racehorse: the results of 275 evaluations. , 1991, Equine veterinary journal.

[15]  G. Carlson,et al.  Hyperkalemic periodic paralysis in horses. , 1990, Journal of the American Veterinary Medical Association.

[16]  J. Ilkiw,et al.  ELECTROCARDIOGRAPHY, HEART SCORE AND HAEMATOLOGY OF HORSES COMPETING IN AN ENDURANCE RIDE. , 1979, Australian veterinary journal.

[17]  G. A. Stewart,et al.  Cardiac monitoring during exercise tests in the horse. 2. Heart rate responses to exercise. , 1976, Australian veterinary journal.

[18]  V. Epstein.  Relationship between potassium administration, hyperkalaemia and the electrocardiogram: an experimental study. , 1984, Equine veterinary journal.

[19]  R. Sweeney,et al.  Ventricular arrhythmias in horses: 21 cases (1984-1989). , 1992, Journal of the American Veterinary Medical Association.