Abstract

Cardiac disease is a major cause of morbidity and mortality in primates.^1-3,7,9 Besides cardiomyopathy associated with vitamin E deficiency, there is limited information regarding cardiac disease in geladas (Theropithecus gelada).⁵

Arrhythmias can be difficult to diagnose in primates as clinical signs are rarely observed prior to death. Anesthetized electrocardiograms (ECGs) have limited diagnostic value if arrhythmias are intermittent, and can be influenced by anesthetic agents. Implantable loop recorders (ILRs) are surgically placed devices that allow for ECG monitoring in awake animals. ILRs have demonstrated promise in reliably detecting arrhythmias in small domestic animals and chimpanzees (Pan troglodytes).^4,6,8

At the Bronx Zoo between 2007 and 2018 there were ten incidents of sudden cardiac death in male geladas, none of which showed premonitory signs. Examinations of three adult male geladas exhibiting no clinical signs included thoracic radiographs, echocardiograms, 12-lead ECGs, and subcutaneous surgical placement of Reveal LINQ Insertable Cardiac Monitors (Medtronic, Minneapolis, MN, USA). Serum lipid profiles, vitamin E, troponin, and complete blood work was performed. Wireless ILR downloads were obtained during behavioral training or automatically when the animal slept within 15 feet of the bluetooth receiver. One male had an elevated troponin level (210 ng/L) and a reduced ejection fraction (46%). Additionally, in that same individual, ILR downloads indicated supraventricular tachycardia and non-sustained ventricular tachycardia. Atrial tachycardia, as well as sinus tachycardia and bradycardia, were observed in the other two individuals. The use of the ILR has the potential to revolutionize our ability to diagnose and treat arrhythmias in primates and other zoological species.

Acknowledgments

The authors thank the veterinary technicians of the Zoological Health Program and the Mammal Department for their assistance in the success of this program. Thank you to Nicholas Aventti and Gowri Raman of Medtronics for helping with downloading logistics.

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