Electrocardiographic observation on goats with urea-ammonia poisoning and a consideration on the main cause of death.

Changes in electrocardiograms, blood pressure, pH, and partial pressure of gases (Po2 and Pco2) in arterial blood were studied in goats poisoned by urea or ammonium compounds under spontaneous and artificial respiration and in nonconvulsive state. Abnormal electrocardiogram patterns, such as ventricular flutter, ventricular premature beat, atrioventricular dissociation, depression of ST-segment and sinus tachycardia, were all observed after the occurrence of tetanic convulsion. The electrocardiogram pattern seen at the respiratory arrest showed sinus or supraventricular tachycardia; respiratory arrest preceded cardiac arrest in all the goats, but one. Blood pressure was markedly elevated, accompanied with tetanic convulsion. Po2 decreased gradually and the level was below 30 mm Hg (37.0 degrees C) at respiratory arrest and the final opisthotonus. Artificial respiration starting at the final opisthotonus could delay the cardiac arrest. Under nonconvulsive urea-poisoning with gallamine triethiodide and with artificial respiration of air or a mixture of air and oxygen to elevate the Po2 level, changes of electrocardiogram, blood pressure, and Po2 were similar to those seen under convulsive urea-poisoning. The main cause of death was discussed and presumed to be respiratory and cardiovascular failure.