A Simple Method for Recording the Electrocardiogram and Heart Rate From Conscious Animals

The small bioelectrical signals of the heart detected at the body surface of animals are usually relayed to the initial amplifier stage of the electrocardiograph by the use of plate, needle or clip electrodes (Clark, Szabuniewicz & McCrady, 1966). In a series of experiments in which rapid and repeated measurements of the electrocardiogram (e.c.g.) and resting heart rate from conscious, unrestrained guinea‐pigs were required none of the standard methods proved suitable and a modification was therefore developed in which the animals stand on plate electrodes. This method has been used to obtain recordings from conscious mice, rats, cats and dogs, and some applications of the method are illustrated in the experiments described in this article.