Vagally Associated Second Degree Atrio-Ventricular Block in a Dog with Severe Azotemia and Evidence of Sympathetic Overdrive.

A 14 years old, 6 kg, mix-breed male dog with severe azotemia due to urinary bladder herniation was presented to our Veterinary Teaching Hospital (VTH). Electrocardiography revealed normal heart rate of 100 bpm, evidence of sinus respiratory arrhythmia (SRA) and frequent second degree atrio-ventricular block following peak inspiratory phase suggestive of vagally-induced atrio-ventricular conduction delay. Echocardiographic examination showed mild mitral regurgitation without any other cardiac changes, and systolic (SAP) and diastolic (DAP) blood pressure values were 185/90 mmHg (SAP/DAP).