Healing of Cortical Bone Grafts in the Dog The Role of Azathioprine

Sixteen unrelated beagles, randomly divided into groups of four, were used in evaluating the role of therapeutic immunosuppression in the healing of fresh cortical bone allografts over a 16-week period. The four groups included: nontreated allograft, treated allograft, nontreated autograft, and treated autograft. A 2.7-cm tibial cortical graft was fixed orthotopically using a dynamic compression plate. Healing was evaluated by radiography and by gross and histologic studies at 2, 4, 8, and 16 weeks after surgery. The treated dogs were immunosuppressed with azathioprine for eight weeks postsurgery. The conclusions were that: temporary immunosuppression did not significantly alter healing of fresh cortical bone autografts; healing of fresh cortical bone allografts in immunosuppressed dogs was similar to healing of fresh cortical bone autografts; slight differences were observed in the healing of bone grafts in all groups after eight weeks; and cellular reaction typical of graft rejection was found in nontreated allografts, but healing still occurred.     

A COMPUTED TOMOGRAPHIC STUDY OF VOLUME AND X-RAY ATTENUATION OF THE LUNGS OF BEAGLES IN VARIOUS BODY POSITIONS

The influence of body position on volume and x-ray attenuation of the lungs of three Beagles was investigated with computed tomography. In left and right lateral recumbency, the dependent lung had decreased volume and increased x-ray attenuation compared with ventral recumbency. Volume and x-ray attenuation of the nondependent lung, however, were unchanged. In dorsal recumbency, there was a vertical gradient of x-ray attenuation being increased dorsally and decreased ventrally compared with ventral recumbency where regional differences in x-ray attenuation were not found. Results indicate a risk of overlooking a mass in the dependent pulmonary parenchyma of dogs in lateral and dorsal recumbency. Regional differences in x-ray attenuation of the lungs of dogs can be avoided if the radiographs are obtained with the dog in ventral recumbency.     

INVESTIGATIONS OF THE LAMENESS IN DOGS IN THE YEARS 1980–1985

The causes of lameness in dogs were analyzed on the basis of radiologic examinations performed in the years 1980–1985. From 1982, there was an increase in the frequency of secondary nutritional hyperparathyroidism and eosinophilic panosteitis and a decrease in frequency of osteochondrosis. The pathogenesis of these diseases is discussed in relation to alternations in diet during this time.     

FLEXION-EXTENSION MYELOGRAPHY OF THE CANINE CAUDA EQUINA

The radiographic appearance of the canine dural end-sac and its behavior during flexion and extension of the spine is described in a myelographic study in 22 normal dogs and 26 dogs with cauda equina compression syndrome. In more than 80% of the dogs, the dural sac ended at the level of the sacrum. There were relatively large individual differences in shape and size of the dural end-sac. In contrast, shape, length, position, and diameter of the dural end-sac at the level of the lumbosacral articulation is extremely constant during flexion and extension in normal individuals. In the 26 dogs with lesions affecting the cauda equina and nerve roots between L6 and the first caudal vertebra, myelography was diagnostic in 21 dogs. Myelographic diagnosis of cauda equina compression was possible in seven dogs with spine in flexion. In 14 dogs, overextension of the spine and imaging in lateral and dorsal recumbency was necessary to establish a diagnosis. The five dogs with nondiagnostic myelograms had either a dural end-sac ending cranially to the lesion (two dogs), diseases not associated with compression (two dogs), or only slight indentations of the contrast medium column (one dog).     

ECTRODACTYLY (SPLIT-HAND DEFORMITY) IN THE DOG

Radiographs of 14 dogs with ectrodactyly of the forelimb were evaluated and the defect classified according to the site of division of the longitudinal axis of the paw. The majority of separations occurred between metacarpal bones one and two, although separations were also noted between metacarpal bones two and three, two and four, and three and four. Other lesions noted in affected limbs included digit contracture, digit aplasia, metacarpal hypoplasia and metacarpal fusions. Bilateral involvement was noted in only one of 14 cases. No breed or sex predisposition was found and there was equal involvement of the left and right limbs.