Histopathologic Findings in the Heart Associated With Telemetry Instrumentation in Beagle Dogs

Conscious telemetry-instrumented dogs are used during cardiovascular safety assessment in early drug development for the collection of cardiovascular function parameters such as electrocardiography (ECG), heart rate, mean arterial pressure, and cardiac contractility. To refine the use of animals for exploratory toxicology studies, these dogs may be repurposed into these studies following failure of their implanted device. Telemetry instrumentation involves surgical placement of a pressure catheter through the left ventricular apex of the heart. Slight variations in placement and extension of the catheter tip into the ventricular chamber lead to variability in cardiac pathology associated with the instrumentation. Reuse of these animals in toxicologic assessments therefore requires the pathologist to be aware of the spectrum of histologic changes that may occur because of telemetry instrumentation. This report describes cardiac findings in 12 telemetry-instrumented male dogs with implant duration ranging from 7 to 37 months and discusses considerations and recommendations for use of these animals.