Electrocardiographic Reference Values in Clinically Healthy Lusitano Horses

SIMPLE SUMMARY: The electrocardiogram is a relevant diagnostic tool for detecting cardiac rhythm disturbances during routine examinations. With the increasing importance of horses as sport animals, cardiology now plays a significant role in equine medicine. In particular, the Lusitano horse has gained worldwide acceptance for its athletic potential. However, the breed’s unique characteristics can influence electrocardiogram results, making it essential to establish reference values for accurate evaluations. Currently, there are no established reference values for the Lusitano horse, and this study aims to bridge this gap. This study involved electrocardiographic evaluations of 82 clinically healthy adult Lusitano horses using lead II and the base–apex lead. The results revealed a median heart rate of 39 beats per minute. The P wave exhibited mainly a bifid configuration, while the QRS complex appeared in several forms; QR and R were the most frequent configurations in lead II, while RS was the most common in the base–apex lead. Most T waves had a biphasic shape in both methods. Statistically significant differences were observed among genders and ages. These results underscore the importance of establishing reference values for athletic horses to improve the accuracy of cardiac evaluations. ABSTRACT: The Lusitano horse is gaining popularity in the equestrian world, and as a result, the significance of applied sports medicine for this breed is growing. As cardiology plays a crucial role in this field, numerous studies have been conducted to establish electrocardiographic reference values in various breeds to ensure a more accurate evaluation. However, studies regarding healthy Lusitano horses are lacking. So, this study aimed to establish electrocardiographic reference values for Lusitano horses, utilizing a sample of 82 clinically healthy animals. The evaluation involved lead II and base–apex lead measurements, with a median heart rate of 39 beats per minute being recorded. The P wave demonstrated a predominantly bifid configuration, while the QRS complex exhibited various forms. The most common QRS configurations were QR and R in lead II, and RS in the base–apex lead. Additionally, most T waves displayed a biphasic shape in both methods. Furthermore, statistically significant differences were noted based on age and gender. Some of the electrocardiographic values obtained differed from those previously published for other breeds. Given the relevance of electrocardiogram in cardiovascular evaluation, these findings bring valuable insights regarding the specific parameters for Lusitano horse and emphasize the importance of obtaining breed-specific electrocardiographic reference values.