Because of bradyarrhythmic complications under anesthesia in two Airedale Terriers, we performed a prospective search of ECG-abnormalities in healthy dogs of that breed. Resting ECG's were screened for routine abnormalities. None of the 42 dogs investigated so far had a completely normal ECG. Among the common abnormalities were: deviation of the mean electrical axis (MEA) in 32 dogs, low voltage QRS-complexes in 22 dogs, and AV-blocks 1st degree in 14 dogs. None of the recorded abnormalities with the exception of AV-blocks, were considered predictors of anesthetic complications. Because of the high frequency of recorded abnormalities, we are continuing this prospective study.