Calcification of the Intervertebral Discs and Curvature of the Radius and Ulna: A Radiographic Survey of Finnish Miniature Dachshunds

BackgroundIntervertebral disc disease (IDD) is a hereditary condition particularly common in Dachshunds. The breed is predisposed to early intervertebral disc degeneration and intervertebral disc calcification (IDC). When calcified, these severely degenerated discs are visible in spinal radiographs. Since the number of calcified discs (NCD) is associated with IDD, spinal radiography can be utilized in screening programmes in attempts to diminish the incidence of IDD in Dachshunds. Our aims were to estimate the heritability and genetic trend of NCD in Dachshunds in Finland and to explore the effect of age at the time of radiographic screening. Since the NCD has a highly skewed distribution, a log-transformed NCD (lnNCD) was also used as an analysed trait. The variance components for both traits were estimated, using the restricted maximum likelihood method. The fixed effects of breed variant, sex, as well as year of screening and the random effects of litter and animal were included in the model. The genetic trends in the NCD and lnNCD were assessed from the estimated breeding values (EBVs) of individual dogs by comparing the mean EBV of dogs born in different years. The breeding values were estimated, using the best linear unbiased prediction animal model. The pedigree in the genetic analyses included a total of 9027 dogs, of which 1567 showed results for NCDs.ResultsThe heritability estimates of the NCD and lnNCD in Dachshunds were high (0.53 and 0.45, respectively). Small genetic improvements were seen as the mean EBVs increased from 100 to 104 and 105 over a 15-year period. The gain in the entire Dachshund population in Finland may differ from that observed, since less than 10 % of the Dachshunds registered have a screening result for NCD. Age at the time of the screening did not significantly affect the NCD or lnNCD.ConclusionsWe recommend systematic radiographic screening for IDC in Dachshunds and adopting EBVs as a tool for selecting breeding dogs. Age at the time of the radiographic screening may not be as important as previously suggested.

Section: Discussioncontrasting

confidence: 99%

Estimate of heritability and genetic trend of intervertebral disc calcification in Dachshunds in Finland

Lappalainen

Mäki²,

Laitinen‐Vapaavuori

2015

“…This would mean that approximately 12 intervertebral discs in the Dachshunds are expected to be calcified according to the histopathological study. In contrary, radiological studies were able to detect 2.5-3.4 [20], 3.5 [21], 3.7 [13], 4.8 (current study) of calcifications in Dachshunds (mean values). This indicates that radiological studies are detecting only about 20-40% of the actually existing disc calcifications that can be identified with histopathology.…”

Section: Discussioncontrasting

confidence: 57%

“…Our results indicate that CDVR were more frequent in our study of Dachshunds surgically treated for disc extrusions compared to previous studies [9,11,13,14,21]. The occurrence of CDVR varies in different studies but conclusions should be made carefully as the study designs, inclusion criteria, age of examined Dachshunds, absence or presence of sedation for radiographic examination and the way radiographs were evaluated (analog or digital) might have influenced the final results [6,8,10,11,14,20]. The Dachshunds included in our study were of all sizes, hair coats and varied in age and the way they were used by the owners.…”

Section: Discussionmentioning

confidence: 96%

Prevalence of radiographic detectable intervertebral disc calcifications in Dachshunds surgically treated for disc extrusion

Rohdin

Jeserevic²,

Viitmaa

et al. 2010

BackgroundAn association between the occurrence of calcified discs, visible on radiographic examination (CDVR), and disc extrusions has been suggested in published literature over the past 10-20 years, mainly from Nordic countries. It has also been postulated that dogs without CDVR would not develop disc extrusions. Furthermore, inheritance of CDVR has been calculated and it has been postulated that, by selecting dogs for breeding with few, or no CDVR, the prevalence of disc extrusions in the Dachshund population may be reduced.MethodsThe prevalence of radiographic detectable intervertebral disc calcifications was calculated from one hundred surgeries for disc extrusion, performed in 95 Dachshunds, in order to determine if the disc causing clinically significant IVDD, had radiographic signs of calcification at the time of confirmed disc extrusion. Inclusion criteria, for each dog, included a complete physical, orthopedic and neurologic examination, radiographs of the entire vertebral column, a myelogram or magnetic resonance imaging examination indicating extradural spinal cord compression, and finally a surgical procedure confirming the diagnosis of a disc extrusion. In addition to descriptive statistics, age correlation with number of calcifications visible at radiographic examination and with CDVR at the surgery site was examined.ResultsWe found that disc extrusions occur as frequently in discs that are found to have radiographic evidence of calcification as those discs that do not have signs of radiographic calcification, and that IVDD (intervertebral disc disease) requiring surgery does occur in the absence of any calcified discs on radiographic examination. We found that calcified discs were more frequent in our Dachshund population compared to previous studies suggesting that disc calcification might be a serious risk factor for developing disc extrusion. Further studies are needed to show, conclusively, if selection of breeding dogs based on CDVR in the Dachshund will reduce the incidence of IVDD. The presence of the calcifications of intervertebral disc should be evaluated with caution, as only part of the calcifications will be detected and the real extent of the disc degeneration may be underestimated.

“…A multiple-choice questionnaire (Additional file 1), similar to one used in a previous study of incidence of IDC in Finnish miniature Dachshunds [26], was applied to determine the occurrence of IDD in Dachshunds. The questionnaire comprised the owners’ assessment of any clinical signs of IDD (ataxia of hind limbs, back or neck pain, unexplained pain attacks, unwillingness to jump onto a sofa), and their frequency (never, seldom, sometimes, often, always) in their dogs.…”

Section: Methodsmentioning

confidence: 99%

“…In a study of Finnish miniature Dachshunds, only one out of 25 dogs without calcifications had had signs of IDD [26]. The association between IDC and IDD has been established as a tool to reduce the occurrence of IDD.…”

Section: Introductionmentioning

confidence: 99%

Intervertebral disc disease in Dachshunds radiographically screened for intervertebral disc calcifications

Lappalainen

Vaittinen

Junnila³

et al. 2014

BackgroundIntervertebral disc disease (IDD) is a very common neurological disease, Dachshunds being the breed most often affected. In this breed, IDD has a hereditary background and is associated with intervertebral disc calcification (IDC), an indicator of severe intervertebral disc degeneration. In Finland, spinal radiography is used, when screening for IDC before breeding Dachshunds. We evaluated the association between IDC and IDD in Finnish Dachshunds radiographically screened for IDC.A questionnaire was sent to owners of 193 radiographically screened Dachshunds aged at least ten years. Clinical signs indicative of IDD were compared with IDC grade (grade 0 = no calcifications, grade 1 = 1 – 2 calcifications, grade 2 = 3 – 4 calcifications and grade 3 = 5 or more calcifications) and with age at the time of the radiographic examination. The diagnosis of IDD was confirmed by a veterinarian.ResultsIDD was common in the study population with 31% of dogs being affected. IDD and IDC were clearly connected (P < 0.001); IDD was rare in dogs with no calcifications (grade 0) and common in dogs with severe IDC (grade 3). The IDC grade was strongly positively associated with frequency of back pain periods (P < 0.001), and dogs with IDC grade 3 had frequent periods of pain. Reluctance to jump onto a sofa had a strong positive association with back pain. No association existed between age of the dog at the time of the radiographic examination and clinical signs indicative of IDD.ConclusionsRadiographically detected IDC and IDD are common in Finnish Dachshunds and are strongly associated with one another. Spinal radiography is an appropriate screening tool for breeders attempting to diminish IDC and IDD in Dachshunds. A breeding program that screens dogs and selects against IDC can be expected to reduce the occurrence of IDD in future. Twenty-four to 48 months of age is a suitable age for screening.Electronic supplementary materialThe online version of this article (doi:10.1186/s13028-014-0089-4) contains supplementary material, which is available to authorized users.