STUDIES ON CLINICAL APPLICATIONS OF ELECTROCARDIOGRAM ON DOGS I. : ELECTROCARDIOGRAM OF SHEPHERD DOGS AND KARAFUTO (SAGHALIEN) DOGS

Twenty-one Shepherd dogs and 22 Karafuto dogs were examined. Limb lead (I, II&III), unipolar limb lead (aVR, aVL&aVF) and unipolar chest lead (V1∿V6) were employed for these experiments. Classification was made of waves and measurements of each wave of each lead. The results are summarized as follows; 1. Arrhythmia was seen in 15 out of 21 cases in the S dogs and in 20 out of 22 cases in the K dogs. All of the arrhythmia were sinus arrhythmia including some cases of respiratory arrhythmia. The cases of sinus arrhythmia showed clinically abnormal heart sound. 2. Electrocardiogram of S dogs traced by three different kinds of lead methods are as follows. P wave mostly showed positive in each lead except for negative waves in leads aVR and V1. PQ segment always showed flat wave paralleled with 0-line except the waves in some cases of leads II and aVR. QRS complex may be divided into 12 types. Through out all lead recordings, qR type was mostly observed with R and Rs types being second. But the QRS complex which was constructed of only Q and S waves were observed in leads aVR, aVL and V1. Further, no S wave was seen in leads II and aVF, and no Q wave was observed in V3 and V4. ST segment mostly showed the flat wave and upward waves. T wave showed mainly positive form but diphasic type was sometimes seen. Notching formation on QRS complex was traced mostly on the downward deflection of R and secondly on top of R waves. Close relation may be recognized between the form of ST segment and direction of deflection of T wave. 3. Electrocardiogram of K dogs are characterized as follows. P wave in most cases showed positive wave excepting negative one in leads aVR and V1. PQ segment showed flat wave in limb lead, aVL and aVF, but in recordings from the unipolar chest lead the segment showed downward deflection. QRS complex may be classified into 12 types. Rs and RS types were mostly seen but the QRS in aVR and aVL was mainly constructed of Q and S waves. In the unipolar chest lead, Q waves were not observed in recording of V3. Upward deflection and 0-line type of ST in limb lead, downward in aVL&aVR, and upward in unipolar chest lead were respectively observed. Positive T waves were observed in most cases, but in aVR and aVL the T waves showed negative. Notchings on QRS were usually found on the downward deflection of R and next most frequently on upward deflection of R. In regard to the relationship between the forms of ST and T waves, same conclusions were reached as in the S dogs. 4. Some differences were observed between the electrocardiograms of S and K dogs, which were concerned with figure and measurement value of each wave in each lead. But fundamental differences were not observed electrocardiographically. 5. In regard to the clinical application of the electrocardiogram on dogs, the authors considered that the electrocardiograph is a useful instrument for diagnose of the heart conditions. First of all fixing method is important : the writers consider it best to put the dog on his back with extremities bandaged to the table, because the movement of the dog may be prevented during the recording of the electrocardiogram. The needle electrode is useful. The electrode is applied to the subcutaneous area under the lead position, then for some time the electrode should be kept as it is, so the injury current may be destroyed and no influence of injury currents may be recognized in the traced wave. It is needful for diagnosis of the heart condition that recording of the electrocardiogram should be made by many leads as possible. But in clinic many leads are not applied to the patient. Therefore, authors consider it practical and useful for clinical examination that diagnosis of arrhythmia be conducted by lead II of the limb lead, and then that unipolar lead be used to learn about the positional changes of the heart. Records from the unipolar chest lead are valuable for learning about the heart muscle condition especially to ascertain if there have been damages to the ventriclar muscles