Research Note: Refining ECG Lead Placement in Dogs

ECG lead placement in dogs is important due to the variability of chest conformation and subsequent heart position. This study measured the accuracy of right atrial and ventricular depolarization based on precordial lead V₁ placement in dogs with different thoracic conformations. Patients were divided into 3 groups (ie, brachymorphic, mesomorphic, dolichomorphic), and 12-lead ECG recordings were taken with precordial lead V₁ in 5 different positions. Right atrial and ventricular depolarization readings varied greatly according to V₁ location. The most consistent readings for all 3 groups came from positioning V₁ at the costochondral junction of the right first intercostal space. This location should be evaluated as the standard for 12-lead ECGs in dogs.