The use of histology to estimate age, understand taphonomic history and diagnose disease in human skeletal and mummified remains is a well-known method. Even though non-human animals experience stress and disease similar to humans, microscopy is rarely applied to faunal remains to obtain a diagnosis. Histological results from a 16th-century Iroquoian dog which had previously been diagnosed by macroscopic and molecular methods with tuberculosis-induced hypertrophic osteopathy (HPO) are presented here. Comparisons indicate that canid microscopic skeletal manifestations of HPO are reminiscent of human alterations caused by this condition. In addition, the microscopy reveals an aggressive form of HPO that was chronic in nature which could not be identified by either macroscopic or molecular methods. By providing an extension to the original diagnosis, the impact of a chronic case of tuberculosis is discussed. This study helps to emphasise the utility of palaeohistopathology in both biological anthropology and zooarchaeology, as it allows for a deeper discussion of the manifestation of HPO and the impact of tuberculosis on both dogs and humans. Copyright © 2008 John Wiley & Sons, Ltd.