Electrocardiographic abnormalities associated with tetanus in two dogs.

Bradycardia, sinus arrest, and second-degree atrioventricular block developed in 2 dogs with tetanus. Clinical signs attributable to bradycardia were not apparent. Administration of atropine resulted in resolution of the arrhythmias. Both dogs responded well to supportive treatment; the bradycardia resolved within 4 days of onset without specific treatment. Tetanus should be included in the differential diagnosis when increased neuromuscular excitability and bradycardia are evident, as is found in toxicity with acetylcholinesterase inhibitors, increased intracranial pressure, and other neurologic disorders.