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

Area of Science:

• Veterinary Pathology
• Cardiovascular Toxicology
• Drug Development Safety Assessment

Background:

• Conscious telemetry-instrumented dogs are vital for collecting cardiovascular data (ECG, heart rate, blood pressure, contractility) during early drug development.
• Repurposing dogs from safety assessments into toxicology studies is a strategy to refine animal use, especially after device failure.
• Telemetry instrumentation involves surgical implantation, with potential for variability in catheter placement leading to cardiac pathology.

Purpose of the Study:

• To describe the spectrum of cardiac findings in telemetry-instrumented dogs.
• To inform pathologists about instrumentation-related cardiac changes for accurate toxicologic assessment.
• To provide recommendations for the ethical and effective reuse of these animals in exploratory toxicology.

Main Methods:

• Histologic examination of cardiac tissues from 12 male beagle dogs with telemetry implants.
• Analysis of cardiac findings in relation to implant duration (7-37 months).
• Review of pathological changes associated with left ventricular apex catheter placement.

Main Results:

• Telemetry instrumentation is associated with a range of cardiac pathologies, varying with catheter placement and duration.
• Specific histologic changes related to the surgical procedure and device presence were observed.
• The findings highlight the need for pathologists to differentiate instrumentation-induced changes from drug-related effects.

Conclusions:

• Pathologists must be aware of cardiac alterations caused by telemetry instrumentation to avoid misinterpreting them as adverse drug effects.
• Understanding the spectrum of these histologic changes is essential for the responsible reuse of instrumented dogs in toxicology studies.
• Recommendations are provided for the appropriate use and assessment of these animals in drug development.