Acta Veterinaria Scandinavica 2007, 49:39 http://www.actavetscand.com/content/49/1/39 occurrence of calcified discs in a dog and the heritability in Norwegian dachshunds is estimated to be 0.15 and 0.22 [8]. In Danish wirehaired dachshunds Jensen and Christensen [9] estimated the heritability to be 0.60 and 0.87. Thus, the potential exists for a breeding programme that could reduce the occurrence of calcified discs and thereby IDD in this breed. Low-field magnetic resonance (MR) imaging is found to be very sensitive in the evaluation of disc degeneration in dogs [10]. However, the cost of MR imaging is high and the number of MR machines for veterinary usage is lim- ited. For screening purposes, a radiographic examination is therefore still the most suitable method for the identifi- cation of calcified discs in a large number of live dachs- hunds. Information obtained by reading radiographs can be included as part of a breeding programme. Different degrees of calcification are found in degenerated chondrodystrophoid discs [11,12]. Discs with minor cal- cifications could be difficult to identify on radiographs. Also, non-calcified discs could be misjudged and read as calcified. By this, false-positive and false-negative errors may be made in reading radiographs for calcified discs. To the authors' knowledge the extent of such errors has not been reported. However, in a pathologic study of 16 one- year old chondrodystrophoid dogs Hansen [4] found cal- cified discs in at least 10 (62.5%) of the dogs, while in a radiographic study of 327 one-year old dachshunds Stigen [7] found calcified discs in 79 (24.2%) of the dogs. On the assumption that most of the dogs in the former study were dachshunds, these two studies together indicate that a radiographic study is far less sensitive than a pathologic study in identification of calcified discs. The present study was performed to test this hypothesis. Methods The vertebral columns were obtained from 20 dachs- hunds that were euthanased for reasons unrelated to research at the Department of Companion Animal Clini- cal Sciences, Norwegian School of Veterinary Science. The case material, including size and coat varieties, sex, age and reason for euthanasia is presented in Table 1. The age of the dachshunds ranged from ten months to 13 years (mean 5.3 years) and there were twelve (60.0%) females. The vertebral columns were separated from the skull, ribs and pelvis by dearticulation. The tail, including the coccy- geal vertebrae, was also removed. The spines were freed of muscle, loose connective tissue and ligaments. Within 24 hours of death, conventional lateral radio- graphs were taken of the cervical, thoracic, lumbar and sacral vertebral columns [13]. The radiographic equip- ment was a Philips Medio 50 CP generator and a Super Rotalix 2550 tube. The cassettes were Cawo 18 × 24 cm rectangle x-ray cassettes containing a green-emitting 100 MR (fine) intensifying screen on one side of a Kodak T- Mat L/RA-film. No grid was used and at exposure the spec- imens were in direct contact with the cassettes. The voltage Table 1: Case material. Dog no. Variety Sex Age, years Reason for euthanasia 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Size, Coat Dwarf, Smoothcoated Dwarf, Longhaired Dwarf, Longhaired Dwarf, Longhaired Dwarf, Longhaired Dwarf, Longhaired Dwarf, Longhaired Standard, Smoothcoated Standard, Smoothcoated Standard, Smoothcoated Standard, Smoothcoated Standard, Wirehaired Standard, Wirehaired Standard, Wirehaired Standard, Wirehaired Standard, Wirehaired Standard, Wirehaired Standard, Wirehaired Standard, Longhaired Standard, Longhaired 8 <1 (10 months) 5 6 6 7 13 <1 (10 months) 5 6 8 <1 (11 months) 2 4 4 5 7 10 3 4 Neurological disorder Vascular ring anomaly Intoxication Neurological disorder Multiple fractures Multiple fractures Pelvic fracture Neurological disorder Neurological disorder Neurological disorder Complications to perineal hernia Owner's request Owner's request Neurological disorder Neurological disorder Pulmonary neoplasm Neurological disorder Owner's request Multiple fractures Neurological disorder Page 2 of 7 (page number not for citation purposes)