Biological spacers were used to prevent epidermally induced failure modes of percutaneous devices in dogs. The implants, however, can still fail due to infection or mechanical trauma (avulsion). The pathophysiology of these failure modes, using Dacron® velour covered Silastic® implants, was investigated. In view of species differences between dogs and humans, further investigations are needed before the relevance of these findings can be extended to possible clinical (human) applications. © 1985.