Electrocardiographic parameters and heart rate variability analysis in free-ranging female South American Coatis (Nasua nasua)

The South American coati (Nasua nasua) is increasingly affected by anthropogenic pressures, making safe handling and physiological monitoring essential for conservation programs. This study aimed to characterize electrocardiographic (ECG) parameters in anesthetized free-ranging coatis and establish preliminary reference values. Ten female coatis (3 kits, 4 juveniles, 3 adults) were captured in Iguaçu National Park, Brazil, and chemically immobilized with intramuscular tiletamine-zolazepam (7 mg/kg). ECG recordings were obtained 30 min post-administration using standard bipolar and unipolar limb leads. Parameters measured included P and T wave amplitudes and durations, QRS complex, PR interval (PRi), QT interval (QTi), RR interval (RRi), ST segment, and mean electrical axes. Heart rate variability (HRV) was assessed using time-domain and nonlinear methods. All coatis exhibited normal sinus rhythm with well-defined ECG waveforms. PRi values (0.062 ± 0.005 s) were concordant with predicted allometric values (p = 0.083), indicating appropriate atrioventricular conduction. QRS morphology and mean electrical axis (71°-156°). No significant differences in ECG or HRV parameters were observed across age groups, indicating stable cardiac electrical activity and autonomic regulation. This study provides the first detailed ECG description for anesthetized coatis, expanding knowledge of their cardiac physiology. The reference values can inform clinical monitoring, field procedures, and conservation interventions.