In selecting animal models, what should your rationale include?

FDA recommends that you provide your rationale for the selection of particular animal models for your animal study. The animal and its related environmental and physiologic attributes should provide a test system that offers a best attempt at simulating the clinical setting. The rationale for the conduct of an animal study should clearly state which of the elements of your risk analysis will be addressed and why the particular animal model was selected. If there are limitations to the animal model such that certain risks of the device are best addressed by bench or cadaver testing, these relationships should be described. Your rationale should also describe inherent challenges to the test system, such as:

• the similarities and differences between the test system and humans in the metabolism of drugs or the use of ancillary devices that represent the standard of care for the procedures utilized in device implantation
• the dimensions of the device and delivery systems, as compared to the same characteristics of the device version intended for human use
• the location of device insertion and the tracking pathway or, if surgically placed, the anatomic point of surgical entry and the surgical technique utilized in the animal versus the human
• size limitations that exist as barriers (exclusive of cost) to use of the most size appropriate and anatomically appropriate model