Acta Veterinaria Scandinavica 2007, 49:39 http://www.actavetscand.com/content/49/1/39 FHiigstuorpeat4hology of disc no. 7 (T1–2) from Dog no. 10 Histopathology of disc no. 7 (T1–2) from Dog no. 10. Cal- cium deposits (arrows) in the nucleus pulposus (Np) and in a broad discontinuous ring within the annulus fibrosus (Af): 'severe' degree of calcification (3). Von Kossa; Bar = 1.6 mm. ity of 0.6 (138/230) and a specificity of 1.0 (273/273) was calculated for the radiographic examination. In 95 discs the degree of calcification was found to be equal in histopathology and radiography. In 125 discs the degree of calcification was higher in histopathology and in 10 it was higher in radiography. Discussion The present study shows that a significantly higher number (45.7% versus 27.4%) of calcified discs are iden- tified by a histopathologic examination compared to a radiographic examination of intervertebral discs in dachs- hunds. This finding verifies the hypothesis presented at the beginning of the present paper. Table 2: The distribution of 503 intervertebral discs on the basis of calcification (+) or not (-) evaluated by a radiographic and a histopathologic examination. Radiology Total Histolopathology Total + + - 138 (27.4%) 92 (18.3%) - 0 273 (54.3%) 138 (27.4%) 365 (72.6%) 230 (45.7%) 273 (54.3%) 503 (100.0%) At the radiographic examination, a total of 148 calcified discs were identified in 18 dogs. This makes a mean of 8.2 calcified discs in each affected individual. Both the per- centage number of dogs with calcified discs (90.0%) and the mean number of such discs in each affected dog are higher than values for corresponding parameters found in previous radiographic studies [6,7,12]. The fact that the present study is related to clinical cases, whereas the pre- vious radiographic studies were related to clinically nor- mal dachshunds, could be the reason for this disparity. In dogs no. 2 and 3, no calcified discs were found at the radiographic examination, but at the histopathologic examination a slight degree of calcification was found in five and 15 discs, respectively. This finding shows that a total absence of calcified discs visible on radiographs of a dachshund is no guarantee for the dog not having exten- sive calcification at histopathologic examination. Of the 92 discs that were found to be calcified only at the histopathologic examination, 84 (91.3%) were noted to have a 'slight' degree, eight a 'moderate' degree and none a 'severe' degree of calcification. This agrees with the gen- eral understanding that an ordinary radiographic exami- nation of the vertebral column in dogs is not very sensitive at detecting minor calcifications of intervertebral discs. The radiographic examination in the present study was done on vertebral columns separated from the skull, ribs and pelvis and freed of soft tissue. This meant that super- imposition of tissue adjacent to the discs (e.g. caput costae and os ilium) was avoided on the radiographs. Also motion blurring was not a problem with the examination of dead specimens. These factors contributed to high tech- nical quality of the radiographs. Therefore, the sensitivity of the radiographic examination in the present study is likely higher than could be expected in similar studies on live dogs. As a consequence, the presented results concern- ing total number of calcified discs and degree of calcifica- tion of individual discs, cannot directly be compared to results from previous radiographic studies [5-7,9,12] on live dogs. The 20 dachshunds included in the present study were euthanased up to 24 hours before being available for the radiographic examination. As a result, rigor mortis was present in several dogs and for these the standard proce- dure for spinal radiography of live dogs [13,16] was inap- propriate. Two dogs (no. 3 and 18) had been subjected to post-mortem examinations immediately after euthanasia and their vertebral columns were thereafter included in the study. To achieve radiographs of high technical quality from more dogs, separated vertebral columns, instead of vertebral columns "in situ", were chosen for radiography. Diagnostic imaging of separated vertebral columns is pre- Page 5 of 7 (page number not for citation purposes)