The T wave in the V10 precordial electrocardiographic lead is negative in healthy Chihuahua dogs

Abstract

Objectives: The T wave polarity in the V10 precordial electrocardiographic (ECG) lead in Chihuahuas is described as positive in the veterinary literature. The aim of this study was to investigate the polarity of the T wave in the V10 precordial ECG lead in clinically healthy Chihuahuas. Our null hypothesis was that healthy Chihuahuas have a negative T wave in V10. Animals, materials and methods: In this prospective study, 67 healthy breederowned Chihuahuas were used. A physical examination, 10-lead ECG and an echocardiogram were performed on each dog. Results: No cardio-respiratory abnormalities were revealed in any of the otherwise healthy dogs. Three out of 67 ECGs were of insufficient quality because of baseline artifacts due to movement of the animal. Two other ECGs showed a nearly iso-electric T wave in the V10 lead. The remaining 62 ECGs showed negative T waves in the V10 lead. Right ventricular hypertrophy was excluded with echocardiography in all dogs. Conclusion: In contrast to previous reports, we found that healthy Chihuahuas have negative T wave in the V10 precordial ECG lead. ª

The polarity and shape of the T wave in lead V-10 in Chihuahuas

“…This possible exception or "peculiarity" of Chihuahuas have been replicated in many subsequent publications (Ettinger & Sutter, 1970;Bolton, 1975;Tilley et al, 1985;Miller & Tilley,1988;Ware, 1994;Smith Jr. & Hadlock, 1995;1;Smith Jr. & Fox, 1999;Nelson 2000;Montoya & Ramirez, 2007;Cotté & Ettinger, 2008;Filippi 2011;Macintire et al, 2012;Mazzini & Prada, 2020;Pascon 2021;Schroeder, 2021). Contradicting this discrepancy, Dijkstra and Szatmári (2009) reported that in Chihuahuas the T-wave in lead V10 is usually negative, rather than positive; therefore, it would not constitute an exception among the different canine breeds. This research study aimed to clarify the polarity and shape of the T-wave in the lead V-10 in a group of healthy Chihuahuas.…”