Spinal hyperostosis in comparative pathology. A useful approach to the concept.

Spinal hyperostosis, an anatomical and radiological concept primarily described in man, is characterized by enthesopathic bony overgrowth on vertebral bodies in the form of spurs or intervertebral bridges. It can also be part of a more diffuse enthesopathic condition, including the appendicular skeleton. These changes are distinct from those of osteoarthrosis. Similar changes can be observed in all kinds of mammals, independent of their type of locomotion (bipodic, quadrumanous, quadrupedic, or aquatic). An anatomical and radiological study is presented of six cases (with histological examination of two dogs and one horse, and observation of macerated specimens of one horse, one equida, and one whale). Comparative pathology allows for a better understanding of the concept of hyperostosis and, even more clearly than in man, this can be distinguished from that of discovertebral pathology although both conditions could be associated in older subjects. The knowledge of spinal hyperostosis in veterinary medicine could--as in man--be of interest to differentiate between this process and other features of vertebral pathology.