ELECTROCARDIOGRAPHIC CONSEQUENCES OF A PERIPATETIC LIFE-STYLE IN GRAYWOLVES (CANIS-LUPUS)

Cardiac chamber enlargement and hypertrophy are normal physiologic res ponses to repetitive endurance exercise activity in human beings and d omestic dogs. Whether similar changes occur in wild animals as a conse quence of increased activity is unknown. We found that free-ranging gr ay wolves (Canis lupus, n=11), the archetypical endurance athlete, hav e electrocardiographic evidence of cardiac chamber enlargement and hyp ertrophy relative to sedentary captive gray wolves (n=20), as demonstr ated by significant increases in QRS duration, QT interval, and QT int erval corrected for heart rate, a tendency towards increased Q, R, and S wave voltages in all leads, and a significant decrease in heart rat e. We conclude that exercise activity level and therefore lifestyle af fects physiologic variables in wild animals. An immediate consequence of this finding is that physiologic measurements obtained from a capti ve wild-animal population with reduced exercise activity level may not accurately reflect the normal physiologic state for free-ranging memb ers of the same species. (C) 1998 Elsevier Science Inc. All rights res erved.