Congenital malformations of the lumbosacral vertebral column are common in neurologically normal French Bulldogs, English Bulldogs, and Pugs, with breed‐specific differences

Abstract

Congenital vertebral malformations are common findings on diagnostic imaging of the vertebral column in “screw‐tailed” brachycephalic dogs. The aims of this study were to evaluate the prevalence and anatomical characteristics of lumbosacral congenital vertebral malformations in French Bulldogs, English Bulldogs, and Pugs presenting for problems unrelated to spinal disease, as well as possible associations with the degree of tail malformation, lumbosacral intervertebral disc herniation, or spondylosis deformans. In this retrospective cross‐sectional study, CT scans of vertebrae L6 to S3 and of the coccygeal vertebrae were reviewed for type of congenital vertebral malformations (hemivertebrae, block vertebrae, lumbosacral transitional vertebrae, and spina bifida), lumbosacral intervertebral disc herniation, lumbosacral spondylosis deformans, and degree of tail malformation. In 76 (51.0%) of the 149 included dogs (53 French Bulldogs, 37 English Bulldogs, and 59 Pugs) at least one type of congenital vertebral malformations was found, with lumbosacral transitional vertebrae being the most common (34.2%). There was a significantly higher prevalence of lumbosacral transitional vertebrae (54.2%) and lower prevalence of hemivertebrae (1.7%) in Pugs compared to English (13.5% and 24.3%, respectively) and French Bulldogs (26.4% and 32.0%, respectively). Tail malformation was significantly more severe in dogs with evidence of hemivertebrae. Congenital vertebral malformations are a common finding in the lumbosacral vertebral column of French Bulldogs, English Bulldogs, and Pugs. These anatomical variances need to be considered when interpreting diagnostic studies and when planning for neurosurgical and neurodiagnostic procedures. Furthermore, this study suggests a possible association between the degree of tail malformation and lumbosacral hemivertebrae.

Tail end of the brachycephalic problem: diagnostic and treatment options for spinal malformations

“…Transitional vertebrae (Fig 5) can occur at any vertebral column junction and retain characteristics of the two adjacent regions. They are a common incidental finding in pugs at the cervicothoracic, thoracolumbar and lumbosacral region, and they tend to be associated with an abnormal vertebral count (Ryan and others 2017, Brocal and others 2018a, Bertram and others 2019). These variations are important to consider when performing spinal surgery and using anatomical landmarks.…”

“…Dogs with a truncated and kinked tail, commonly known as a screw‐tail, such as the French bulldog, English bulldog and Boston terrier, are predisposed to vertebral column malformations, and recently a mutation in the Dishevelled 2 gene has been reported as a contributing factor (Mansour and others 2018). Interestingly, despite being phenotypically very similar to these predisposed breeds, pugs do not have a screw‐tail and belong to a completely different genetic clade (Parker and others 2017, Mansour and others 2018, Bertram and others 2019). This is probably the reason why they have different types, frequency and location of vertebral malformations (Ryan and others 2017).…”

Epidemiological study of congenital malformations of the vertebral column in French bulldogs, English bulldogs and pugs

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] Vertebral body malformations' origin is classified as either defects of segmentation (block vertebra) or defects of formation, which can be differentiated in aplastic (hemivertebrae) and hypoplastic malformations (wedge shape vertebrae, butterfly vertebrae), transitional vertebrae and neural tube defects. 4,12,15 They often are incidental findings during diagnostic imaging investigation regarding clinical issues unrelated to the vertebral column. 4,7,9,12,[15][16][17][18][19] Dogs can show radiological signs like deviation of normal vertebral axis (kyphosis, lordosis, scoliosis) or vertebral step formation.…”

“…4,12,15 They often are incidental findings during diagnostic imaging investigation regarding clinical issues unrelated to the vertebral column. 4,7,9,12,[15][16][17][18][19] Dogs can show radiological signs like deviation of normal vertebral axis (kyphosis, lordosis, scoliosis) or vertebral step formation. 2,4,6,9,12,17,[19][20][21][22][23] If neurological deficits are present, myelopathic signs are thought to be associated with both number and type of thoracolumbar vertebral malformations.…”

“…Almost all studies investigating CVBM are retrospective, describing a defined segment of the vertebral column and commonly include a low number of patients. [2][3][4][5]8,9,15,17,19,21 The aim of the study was to prospectively evaluate the associations between CVBM along the entire vertebral column and tail malformation, neurological deficits, as well as occurrence of accompanying orthopaedic diseases, specifically HD and patellar luxation in a cohort of brachycephalic dogs from Germany. The hypotheses of the study were: (i) Distribution and types of CVBM in a German brachycephalic dog population do not differ from reported results in literature.…”