3.4.6 Heart rate and rhythm
It is essential that a suitable period of time is spent in assessing cardiac rhythm by auscultation because some significant arrhythmias are intermittent. It is also important to measure the heart rate when the horse has settled. Many horses will have a raised heart rate for some minutes and some may never have a true resting heart rate in the presence of the clinician. The horse's attitude should be taken into account because accurate measurement of heart rate is extremely useful. A tachycardia is one of the important signs of significant cardiac disease, although it is not seen in all cases. A true resting heart rate above 45 bpm should be regarded as abnormal and a cause should be identified, all be it that exciteis the most likely factor.