The position and shape of osteophyte formations at canine vertebral endplates and its influence on radiographic diagnosis.

The relationship between the risk of missing osteophytes in lateral radiographs and their position was determined in a sample of German shepherd dogs (GSDs, n = 42) and dachshunds (DHs, n = 36). Only 10% of osteophytes which were not detected on radiographs were located in the ventral median area (position 1) and classified as type 1 (small spur with narrow base). The highest risk for being affected next to the intervertebral foramen and/or the dorsal area of the vertebral endplate (position 3) was noticed in the lumbar segment (95% CI: 5.2-9.8% in DHs; 11.9-17.7% in GSDs). The minimum risk of missing osteophytes in this position radiologically was 33.3% in the GSDs and 26.4% in the DHs. In the GSDs a higher proportion of type 2 osteophytes (spur with broader base of origin, tending to extend up to half the way along the disc space) was not visualized on radiographs. Peak incidences of osteophytes in positions 1 and 3 were located at the centres of spinal flexion and extension. Therefore, distribution patterns of osteophytes in these positions confirmed mechanical factors being important in pathogenesis of vertebral osteophytosis.