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Alternative classification and screening protocol for transitional lumbosacral vertebra in German shepherd dogs.

Lappalainen AK, Salomaa R, Junnila J, Snellman M, Laitinen-Vapaavuori O - Acta Vet. Scand. (2012)

Bottom Line: Eight dogs had eight lumbar vertebrae.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.

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Affiliation: Section of Diagnostic Imaging, Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland. anu.k.lappalainen@helsinki.fi

ABSTRACT

Background: 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. 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.

Methods: The 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.

Results: In 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.

Conclusions: We 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.

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A CT volume-rendering technique image of a German shepherd dog radiographically diagnosed as type 4. A small transverse process on the left side, not visible in the radiographs, is seen (arrow).
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Figure 14: A CT volume-rendering technique image of a German shepherd dog radiographically diagnosed as type 4. A small transverse process on the left side, not visible in the radiographs, is seen (arrow).

Mentions: A CT study was performed in 16 dogs, of which nine dogs had abnormal sacrum and seven were normal. The abnormal findings are presented in Table 2. With CT, the shape of the transverse processes and median crest of the sacrum were easily identified (Figures 9–11). Separation of the S1 spinous process from the median crest of the sacrum seen in the ventrodorsal radiographs (Figure 3) appeared as a deep indentation in the median crest (Figure 9) in CT. One dog classified as type 4, based on radiographs (dog 8 in Table 2) was diagnosed as having a small unilateral transverse process (Figure 14). In two dogs (dogs 3 and 5 in Table 2), the classification based on ventrodorsal radiographs would have changed from lumbar to intermediate type.


Alternative classification and screening protocol for transitional lumbosacral vertebra in German shepherd dogs.

Lappalainen AK, Salomaa R, Junnila J, Snellman M, Laitinen-Vapaavuori O - Acta Vet. Scand. (2012)

A CT volume-rendering technique image of a German shepherd dog radiographically diagnosed as type 4. A small transverse process on the left side, not visible in the radiographs, is seen (arrow).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3403972&req=5

Figure 14: A CT volume-rendering technique image of a German shepherd dog radiographically diagnosed as type 4. A small transverse process on the left side, not visible in the radiographs, is seen (arrow).
Mentions: A CT study was performed in 16 dogs, of which nine dogs had abnormal sacrum and seven were normal. The abnormal findings are presented in Table 2. With CT, the shape of the transverse processes and median crest of the sacrum were easily identified (Figures 9–11). Separation of the S1 spinous process from the median crest of the sacrum seen in the ventrodorsal radiographs (Figure 3) appeared as a deep indentation in the median crest (Figure 9) in CT. One dog classified as type 4, based on radiographs (dog 8 in Table 2) was diagnosed as having a small unilateral transverse process (Figure 14). In two dogs (dogs 3 and 5 in Table 2), the classification based on ventrodorsal radiographs would have changed from lumbar to intermediate type.

Bottom Line: Eight dogs had eight lumbar vertebrae.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Diagnostic Imaging, Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland. anu.k.lappalainen@helsinki.fi

ABSTRACT

Background: 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. 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.

Methods: The 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.

Results: In 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.

Conclusions: We 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.

Show MeSH
Related in: MedlinePlus