Calcium hydroxylapatite deposition disease in a Great Dane Puppy

A 10-week-old male Great Dane Puppy was presented for sudden onset tetraataxia and severe paresis of the front legs. Mineral deposits were detected radiographically, at gross postmortem examination, and light microscopically between the vertebral arches of multiple cervical and lumbar vertebrae. These deposits were associated with the interarchial ligaments (ligamentia interarcualia), along the interfaces of the synovium and articular cartilage of multiple cervical, thoracic, and lumbar facets, on the dorsal aspect of several thoracic intervertebral discs, and at the insertion of muscles at the lateral aspect of several cervical and thoracic vertebral bodies. The mineral deposits were associated with a granulomatous inflammation and synovial fibrocartilaginous metaplasia and proliferation, which was focally exuberant. X-ray diffraction analyses of the mineral deposits revealed calcium hydroxylapatite as the major component. The clinical signs in this puppy were due to focal compression of the spinal cord by marked extraarticular ligament-associated fibrocartilaginous proliferation.