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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.

Focal premature closure of long-bone physes was the cause of conformational abnormalities that affected about 1% of a herd of dairy replacement calves. Affected calves were noticed to "bunny hop" by 3 months of age, and by 6 months of age, they developed abnormal conformation characterized by short pelvic limbs. This condition resembled "hyena disease," which has been described in dairy calves in Europe and Japan. With the exception of the aforementioned abnormalities and femoropatellar joint distention, a group of 5 affected calves examined were clinically normal. At necropsy, focal to almost complete closure of physes was found in the humeri, tibias, and femurs. Cause was not established for the condition; however, it was discovered that the calves had been given supplemental vitamin A/D3 in amounts greater than 10 times those recommended.

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.

Effects of exposure to ambient air (20 to 22 C) on articular cartilage from rabbits were evaluated. Bilateral arthrotomies were performed on the stifles of 18 New Zealand White rabbits. The cranial surface of the left distal femur, including the articular cartilage of the trochlea, was exposed to air for 2 hours. The right stifle was opened and closed immediately. Six rabbits were killed at the end of the surgical operation (group 1), 6 after 2 weeks (group 2), and 6 after 4 weeks (group 3), and femurs were harvested. A distinct color change was seen in the exposed cartilage in group 1; however, minimal change was detected in group 2, and no change was seen in group 3. Proteoglycan content did not differ between the exposed and control cartilage in any group. The number of viable cells and empty lacunae in articular cartilage did not differ between the exposed and control femurs. Total cell counts and degenerative cell counts were similar, comparing the left and right trochlea in groups 1 and 3. A significant increase in cellularity was noticed in the radial zone of the exposed cartilage in group 2 (P less than 0.01). In the same group, a significantly increased number of degenerative cells were seen in the tangential zone of the exposed cartilage (P less than 0.05). Changes in cellularity were consistent with cartilage damage. Seemingly, exposing articular cartilage to air for 2 hours causes reversible cartilage damage.

Chronic arthritis caused by caprine arthritis-encephalitis virus was observed after the introduction of new animals into a goat herd. There were high frequency of carpal hygroma and clinical signs of stiffness. The disease was progressive and produced a debilitating lameness among 30% of the affected animals. Laboratory findings were limited to alterations in synovial fluid which showed increased numbers of lymphocytes. Pathologic changes were observed in the joints, bursae, and adjacent tissues. Vascular injury and capillary leakage resulted in exudation into synovial cavities. Fibrin coated the synovial lining and formed (amorphous) long thread-like or broad-based villi. The articular cartilage was eroded. Cartilage erosion and penetration of the articular cartilage by pannus were associated with the presence of subchondral pseudocysts. The morphologic changes in bone and synovial tissues were like those described in human rheumatoid arthritis, except that rheumatoid nodules were not observed.

A solitary renal adenoma was an incidental finding at the pole of a kidney of an aged male Atlantic bottle-nosed dolphin (Tursiops truncatus) which had been captured in the Gulf of Mexico near St. Petersburg Beach, Fla, and maintained at Marine Attractions, Inc, St. Petersburg. The only other significant findings were widespread cutaneous lesions of Lobo disease.