Asymptomatic radiographic disappearance of calcified intervertebral disc material in the Dachshund.

The occurrence of asymptomatic disappearance of intervertebral disc calcification was evaluated in a radiographic prospective longitudinal study of 40 Dachshunds followed from 6 or 12 months of age to 2 years of age. Radiographic follow-up was performed at 3 to 4 years of age in 12 dogs. Disappearance of calcified disc material was observed in 9 thoracic and 1 lumbar intervertebral discs. The crude incidence rate tended to increase with age from 1 year of age. The features of the disappearing calcifications involved indicate that the phenomenon is part of the progressive degenerative process. A possible pathogenesis includes tearing of the annulus fibrosus due to the severe degeneration of the disc, followed by an inflammatory response to nuclear material and phagocytic resorption of calcified material.