Abstract
1) The cardiac rhythms of dogs, the respiratory arrhythmias in particular, were studied by “Cardiotachograph” in experimentally induced hyper- and hypo-thyroidism.
2) In hyperthyroidism, besides tachycardias, marked decrease and finally complete disappearance of respiratory arrhythmias were noticed These can be looked upon as characteristics in hyperthyroidism.
3) In hypothyroidism, on the contrary, bradycardias were accom-panied by exaggerated respiratory arrhythmias.
4) There was noticed a distinct correlation between the respiratory arrhythmias and pulse rates throughout the experimental conditions.
5) These changes in respiratory arrhythmia were found to be due mainly to changes in the expiratory pulse intervals, the inspiratory pulse intervals, on the other hand, being modified but little.
