Abstract
BackgroundLumbosacral transitional vertebra (LTV) is a common congenital and hereditary anomaly in many dog breeds. It predisposes to premature degeneration of the lumbosacral junction, and is a frequent cause of cauda equina syndrome, especially in German shepherd dogs. Ventrodorsal hip radiographs are most often used in diagnosis of LTV in screening programs. In this study, value of laterolateral lumbar spine radiographs as additions to ventrodorsal radiographs in diagnosis of LTV, and characteristics of LTV and the eighth lumbar vertebra (L8) in laterolateral radiographs were studied. Additionally, computed tomography (CT) features of different types of LTV were elucidated.MethodsThe ventrodorsal pelvic and laterolateral lumbar spine radiographs of 228 German shepherd dogs were evaluated for existence and type of LTV. Morphology of transverse processes was used in classification of LTV in ventrodorsal radiographs. The relative length of sixth (L6) and seventh (L7) vertebrae (L6/L7) was used in characterization of these vertebrae in laterolateral radiographs. CT studies were available for 16 dogs, and they were used for more detailed characterization of different types of LTV. Non-parametric χ2 statistics, generalized logit model for multinomial data, and one-way analysis of variance was used for statistical analyses.ResultsIn all, 92 (40%) dogs had a LTV, the most common type being separation of first spinous process from the median crest of the sacrum in 62 dogs (67% of LTV). Eight dogs had eight lumbar vertebrae. Those dogs with LTV had longer L7 in relation to L6 than dogs with normal lumbosacral junctions. When L6/L7 decreased by 0.1 units, the proportion of dogs belonging to the group with L8 was 14-fold higher than in the group with normal lumbosacral junctions. L8 resembled first sacral vertebra (S1) in length and position and was therefore classified as one type of LTV. With CT it was shown that categorizing LTV, based on shape and visibility of transverse processes seen in ventrodorsal radiographs, could be misleading.ConclusionsWe suggest that L8 be included as a part of the LTV complex, and the laterolateral radiographs of the lumbar spine be considered as an addition to ventrodorsal projections in the screening protocols for LTV.
Highlights
Lumbosacral transitional vertebra (LTV) is a common congenital and hereditary anomaly in many dog breeds
LTV was diagnosed in 92 dogs (40.4%), based on ventrodorsal and/or laterolateral radiographs
LTV was diagnosed from both projections in 15 cases (16.3%) from only the ventrodorsal radiograph in 62 cases (67.4%) and from only the laterolateral radiograph in ten cases (8.7%)
Summary
Lumbosacral transitional vertebra (LTV) is a common congenital and hereditary anomaly in many dog breeds. It predisposes to premature degeneration of the lumbosacral junction, and is a frequent cause of cauda equina syndrome, especially in German shepherd dogs. Several classification systems of LTV, based on the morphology of the sacral wings and their attachment to the ilium, have been used It can be classified, based on the morphological characteristics of the transverse processes and their relationship to the ilium seen in ventrodorsal radiographs [6], or based on alterations of the costal processes (this is synonymous with the transverse process used commonly in veterinary literature) and ventral alar elements [7]. It seems possible that the presence of L8 is part of the LTV complex [9]
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