Arrhythmias Across the Tree of Life: Comparative Insights for Human Electrophysiology

Barbara Natterson-Horowitz^1,2*Kathy Wright³Glenn Van Steenkiste⁴Annelies Decloedt⁴Allison Lynne Gagnon⁵Xinjiang Cai⁶

• ¹Division of Cardiology, UCLA David Geffen School of Medicine, Los Angeles, CA, United States
• ²Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA, United States
• ³MedVet Medical & Cancer Centers for Pets, Fairfax, OH, United States
• ⁴Equine Cardioteam Ghent, Dept. of Internal Medicine, Reproduction and Population Medicine, Ghent University, Ghent, Belgium
• ⁵Department of Medicine and Epidemiology, School of Veterinary Medicine at University of California-Davis, Davis, CA, United States
• ⁶Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States

Introduction: Arrhythmias in non-human animals offer insights into human electrophysiology, yet physicians may be unaware of their occurrence and significance. This paper presents selected examples of arrhythmias in dogs, horses, and birds— as an invitation to human cardiologists to explore how animal models can illuminate mechanisms, genetics, and therapeutic approaches relevant to human electrophysiology. Methods: Leading veterinary cardiologists compiled overviews of common arrhythmias in dogs, cats, horses and birds. Genetic predisposition, natural history, therapeutic approaches, and epidemiology were compared across these species and humans, highlighting translational opportunities. Results: Common human arrhythmias including atrial fibrillation, bradycardia, ventricular tachycardia, and arrhythmogenic right ventricular cardiomyopathy occur naturally in dogs, cats, horses, and birds. Cross-species differences in disease expression provide unique insights into mechanisms of arrhythmia vulnerability and resistance. Dogs develop similar inherited arrhythmogenic diseases but with distinct phenotypes. Horses experience atrial fibrillation without thromboembolic complications, revealing potential protective pathways. They also demonstrate extreme exercise-induced arrhythmia susceptibility, isolating exercise as an arrhythmogenic trigger. Avian species exhibit remarkable adaptation to cardiac loading conditions that would be pathological in mammals. These comparative observations across species highlight novel mechanisms underlying both susceptibility and resistance to arrhythmias and conduction disorders, offering unexplored therapeutic targets for human patients. Discussion: Cross-species knowledge offers direct translational value for human electrophysiology—from genetic markers in Labrador Retrievers with supraventricular tachycardia to cardiac loading paradigms in broiler chickens. Breaking down disciplinary barriers through shared research initiatives and integrated training represents an essential, underutilized strategy for advancing arrhythmia diagnosis, treatment, and prevention in human patients.