Calcium phosphate deposition disease in great danes.

A new clinicopathologic syndrome, possibly familial, in Great Dane dogs, resembles the familial childhood variant of calcium pyrophosphate dihydrate deposit disease in man, except that the mineral deposits were composed of amorphous calcium phosphate or hydroxyapatite rather than pyrophosphate. The syndrome was characterized clinically by paraplegia and incoordination in very young puppies which was caused by concentric constriction of the posterior cervical spinal cord. Canal stenosis resulted from dorsal displacement of the seventh cervical vertebra and deformation of the vertebral articular processes. Mineral deposition in the diarthrodial joints of the axial skeleton could be seen on radiographs of weanling puppies, and the appendicular skeleton became involved as the dogs matured. Periarticular mineralization of the limbs was associated with shorter bones, a thin cortex, abnormal bone curvature, and increased medullary trabeculae. Bone alterations were associated with abnormalities of the growth plate, which had focal areas of cartilage calcification. Soft tissue mineralization, seen in all dogs, was a primary feature of the disease process. Serum calcium concentrations were within the normal range, but serum phosphorus concentrations were decreased.