Articular chondrocalcinosis of the humeral head in greyhounds.

Of 143 Greyhounds necropsied consecutively, 6 (4%) had chondrocalcinosis of the scapulohumeral joint; lesions were identified in 6 additional dogs. Lesions were seen exclusively in the humeral head, mainly in the plateau region. The lesions in the dogs of the initial group were unilateral, but 2 of the 6 additional dogs had bilateral lesions. Focal mineralization of articular cartilage appeared as a white raised nidus, sometimes surrounded by a translucent halo in the opaque cartilage. Circular, small translucent cartilage foci, with or without beginning mineralization, were adjacent to definitive chondrocalcinosis lesions. Chondrocyte necrosis and matrix degradation were considered to antedate appearance of matrical mineral granules; mineralization of the cartilage was considered a secondary process, but not necessarily an epiphenomenon. Scanning electron microscopy indicated that the chondrocalcinosis lesion was composed of deposits of irregularly fused stone material that, in scanning and transmission electron micrographs, was composed of irregular spheroids, 0.05 to 0.5 micron in diameter. The spheroids contained poorly formed needle-like crystals of apatite. Sparse transformation of the mineral phase into hydroxyapatite was considered to be attributable to a biological mechanism that inhibited phase transition. Cartilage degeneration and chondrocalcinosis of the plateau region of the humeral head appear to be unique lesions that develop in young Greyhounds. It is possible that these lesions are the result of the biomechanical stress of training and racing.

Erosive polyarthritis in two greyhounds.

Clinical signs of disease, treatment, laboratory findings, and gross and microscopic changes of erosive polyarthritis in 2 Greyhounds are described. A microscopic feature that may help distinguish this condition from other types of arthritis is extensive necrosis of deep articular cartilage zones, with relative sparing of the more superficial surface cartilage. We believe that the disease in the 2 dogs of this report was identical to that encountered previously in Britain and Australia. Bacteriologic culture and serologic investigation failed to reveal the causative agent.

Pseudoachondroplastic dysplasia in miniature poodles: clinical, radiologic, and pathologic features.

The clinical, radiologic, and pathologic features of pseudoachondroplastic dysplasia were studied in 13 affected Miniature Poodles. The disease became evident when pups were about 3 weeks old. Normal-appearing and affected pups were in the same litter, and both sexes were affected. Abnormal locomotion with abducted hindlimbs and flattened rib cages were accompanied by short, bent limbs and enlarged joints. Radiographically, areas of stippling and patchy densities were evident in the epiphyses. Histologically, these densities were identified as areas of bone associated with retarded ossification. After growth is completed, the epiphyses, ossify, but the bones are shortened and deformed. General health appears normal, except for restricted locomotion due to secondary arthritis and difficult breathing in dogs with a deformed thorax.

Morphology of fracture nonunion and osteomyelitis.

The author reviews the types and pathogenesis of fractures that fail to heal. A discussion of acute osteomyelitis and the causes of hematogenous disease is included. Classifications of osteomyelitis and idiopathic bone inflammations are described.

The histological characteristics of congenital coxa vara: a case report of a five year old boy.

In a 51/2 year old boy with unilateral coxa vara who died of unrelated causes histological sections were made of the proximal femora and pelvic growth plates. The proximal femora were also perfused to study the pattern of arterial supply. Evidence of active endochondral ossification was not detectable in growth plates of the affected right femur, the clinically and roentgenographically normal left femur and the pelvis, including a Salter Type II fissure fracture. The endochondral ossification defect found in growth plates of the proximal right femur and pelvis was associated with a reduction in the number and caliber of intraosseous arteries supplying the metaphyseal sides of the growth plates in the proximal femur and those supplying the subchondral region and extraosseous medial ascending cervical arteries on the surface of the femoral neck. This deficiency in endochondral ossification resembles a form of dwarfism associated with a coxa vara and a generalized growth plate disorder.