Canine electrocardiographs are common procedures in a small animal veterinary practice. They are normally used as a diagnostic tool when canine heart disease is suspected and used to monitor heart function in the operating room. An electrocardiogram determines whether cardiac rate and rhythm is normal and is often a pre-operative procedure in older or overweight dogs. There are typically six lead systems (placement protocols) determined by the type of machine being used. Leads I, II, and III are called bipolar limb leads and detail the electrical voltage being produced by the heart between two areas on the dog's body. The augmented unipolar limb leads (aVR, aVL, aVF) compare cardiac electrical stimulation at one limb to a central point of the heart. Because canine electrocardiograms can only be performed in a clinical setting, it is important that dog owners educate themselves on how the procedure is performed by the vet or vet tech.
Place a blanket or heavy-duty mat on the floor or a non-metal table.
Restrain the dog by having an assistant hold the dog in a standing position or placing him in right lateral recumbency (on his right side) on the blanket.
Spray alcohol or put contact gel on the dog's skin at the elbow on both front and back legs, making sure that the alcohol or gel contacts the skin and not hair.
Attach the right lead to the skin of the right front elbow and the left lead to the skin of the left front elbow (Lead I).
Clip the right lead to the skin of the right front elbow and the left lead to the left back elbow (Lead II).
Place the right lead on the left front elbow and the left lead on the left back elbow (Lead III).
Follow Steps 1 through 3 in the preceding section.
Attach the left unipolar lead to the elbow of the left front leg and the other unipolar lead to the elbow of the back left leg. Clip the singular lead to the elbow of the right front leg (Lead aVR).
Clip the left unipolar lead to the elbow of the left rear leg and the other unipolar lead to the elbow of the right front leg. Place the singular lead on the elbow of the left front leg (Lead aVL).
Place the left unipolar lead on the elbow of the left front leg and the other unipolar lead on the elbow of the right front leg. Clip the singular lead to the elbow of the left back leg (Lead aVF).
If the dog is particularly hairy, it may be necessary to clip the hair at the attachment sites for the clips to make full contact with the skin. Muzzle the dog if he appears irritated or angry during the procedure. Handler safety is of utmost importance.
Make sure the leads are attached to the dog correctly according to the type of machine you are using prior to starting the electrocardiograph. If incorrect leads are used, the wave forms will lead to an improper diagnosis. Keep a spray bottle of alcohol handy to use if the skin under the leads becomes dry--this will result in poor electrode transmission.