An apparatus for non-invasively measuring an electrocardiogram (ECG) in a conscious ambulatory subject includes an electrically conductive platform. The electrically conductive platform establishes an electrical connection with the subject at one of a position forward (e.g., rostral to) or a position rearward (e.g., caudal to) the heart. An additional electrical connection is established at the other of a position forward (e.g., rostral to) or a position rearward (e.g., caudal to) on the subject. The position rearward to (e.g., caudal to) the heart can be the tail of the subject. The additional electrical connection can be established by a movable electrode, an electrically conductive ringlet, an additional electrically conductive platform, a region of conductive material, an electrically conductive dome, a food element, or one or more electrically conductive posts.