A Combination of Atrioventricular Block and Sinoatrial Block in a Horse

In the process of carrying out a routine check up examination on a group of horses of a riding school in Shiraz, a horse demonstrated frequent long pauses in heart rate of 33beats per minute on auscultation. A base apex electrocardiogram (ECG) was recorded to determine the type of conduction disturbance. At the time of ECG recording, the animal was normal with no apparent sign of any body disorders and respiratory movement and temperature were within normal range. CBC and serum biochemical analysis carried out were within normal limits of our school reference values. The horse was given a light exercise and was examined immediately after exercise and 15 minutes thereafter. The heart rate immediately after the end of exercise was 65 bpm and slowed down to 35 bpm 15 minutes after exercise with no sign of heart block.