Paired invasive and oscillometric measurements were taken in 24 dogs every 5minutes during anaesthesia (9 to 37 measurements per dog). Agreement between measurement methods was explored using Bland-Altman plots. To determine the accuracy of the oscillometric measurements, the results were compared with the guidelines recommended by the American College of Veterinary Internal Medicine and the Association for the Advancement of Medical Instrumentation. In total, 493 paired readings were obtained: 98·6% of oscillometric readings were successful. Biases (±standard deviation) for oscillometric readings of systolic arterial blood pressure and mean arterial blood pressure were 2·1 (±11·5) and -9·8 (±7·6) mm Hg, indicating slight over- and under-estimation, respectively, versus invasive measurements. More than 50% and 80% of systolic arterial and mean arterial pressure measurements were within 10 and 20 mmHg of invasively measured values, respectively. A large negative bias (-14·1 ±9·2mmHg) against invasive measurements revealed that the oscillometric measures of diastolic arterial blood pressure measurements were under-estimated. In healthy adult anaesthetised dogs, this oscillometric monitor met the American College of Veterinary Internal Medicine requirements for systolic arterial and mean arterial pressure measurement but failed to meet the requirements for the measurement of diastolic arterial pressure.