Abstract
Background:
Electrocardiography is widely used in feline cardiology, yet precordial lead placement remains poorly standardized for this species. Although six-lead precordial systems have been validated in dogs, their applicability to cats remains uncertain. This is due to the species’ distinct thoracic conformation and the potential stress associated with electrode placement. A simplified precordial arrangement may improve patient comfort, but its diagnostic equivalence has not been fully investigated.

Aim:
To compare six (6P) and four (4P) precordial lead systems in feline electrocardiography and evaluate their clinical applicability, impact on wave measurements, and patient tolerance.

Methods:
Forty healthy, non-sedated adult cats were included. All animals underwent two electrocardiographic examinations in right lateral recumbency. The 6P system consisted of electrodes positioned at predefined locations across the right and left hemithorax to generate six precordial leads. The 4P system used four proportionally spaced electrodes on the left hemithorax. Amplitudes and durations of P, R, S, and T waves were recorded and compared within and between systems. Associations with demographic variables were assessed. Observational assessment of patient tolerance was conducted during both examinations.

Results:
Wave morphology varied slightly between systems. R-wave amplitude was consistently higher in the 6P system and showed a progressive decrease from V2 toward caudodorsal leads. The 4P system produced marginally longer P-wave durations. In contrast, R-, S-, and T-wave amplitudes tended to be higher in the 6P recordings. No significant associations were identified between electrocardiographic measurements and age, sex, or body weight. Cats demonstrated visibly greater tolerance to the 4P system, with fewer attempts to reposition or resist handling.

Conclusion:
Both the 6P and 4P precordial lead systems provide reliable electrocardiographic tracings in cats and can be used in clinical practice. However, the improved patient tolerance observed with the 4P arrangement suggests that it may be preferable in routine examinations. This approach maintains diagnostic usefulness while enhancing feline comfort.

Key words: Cardiology; Electrocardiography; Felines; Thorax