Short QT intervals in African lions

Area of Science:

• Veterinary Science
• Cardiac Electrophysiology
• Comparative Physiology

Background:

• The cardiac conduction system in large carnivores, particularly African lions (Panthera leo), is poorly understood.
• Previous reports noted short QT intervals in anesthetized, zoo-kept lions, suggesting potential environmental influences.

Purpose of the Study:

• To record the first electrocardiograms (ECGs) from wild, conscious lions.
• To compare cardiac electrophysiology, specifically QT intervals, between wild and zoo-kept lions.
• To test the hypothesis that short QT intervals are unique to zoo-kept lions.

Main Methods:

• Macroscopic and histological examination of heart tissue from nine healthy zoo lions.
• ECG recordings from nine anesthetized zoo-kept lions.
• ECG recordings from 15 anesthetized and conscious wild lions in Africa.

Main Results:

• Histological and topographical heart descriptions aligned with existing literature.
• Conscious wild lions had a mean heart rate of 70 ± 4 beats/min, with nocturnal increases.
• QT intervals were significantly longer in wild lions (398 ± 40 ms) compared to zoo lions (297 ± 9 ms), independent of anesthesia or heart rate.

Conclusions:

• Significant QT interval differences exist between wild and zoo-kept lions, suggesting functional disparities in cardiac electrophysiology.
• These disparities may be linked to variations in physical fitness and environmental factors.
• Findings emphasize the plasticity of cardiac electrophysiology and have implications for conservation and animal welfare.