Content continues after advertisement

Congenital Malformations of the Lumbosacral Vertebral Column

Kristyn D. Broaddus, DVM, MS, DACVS, Veterinary Services of Hanover, Mechanicsville, Virginia

Sign in to Print/View PDF

In the Literature

Bertram S, Ter Haar G, De Decker S. Congenital malformations of the lumbosacral vertebral column are common in neurologically normal French bulldogs, English bulldogs, and pugs, with breed-specific differences. Vet Radiol Ultrasound. 2019;60(4):400-408.


French bulldogs, English bulldogs, and pugs can be grouped together based on brachycephalic anatomy. They are known to have respiratory difficulty due to shortened noses and share a propensity for congenital vertebral malformations. These breeds are also known to have block vertebrae, hemivertebrae, transitional vertebrae, and neural tube defects.1 A study revealed that the degree of screw-tail in French bulldogs correlates with the severity of hemivertebrae in the thoracic region.2

The current study examined 149 CT scans of vertebrae L6 to S3 and coccygeal vertebrae in neurologically normal pugs, French bulldogs, and English bulldogs over a 6-year period. The goal of the study was to determine whether vertebral lumbosacral (LS) malformations were present in neurologically normal dogs and whether the severity of tail deformity was linked to the presence of vertebral malformations in the LS region. Fifty-one percent of dogs had evidence of at least one type of congenital vertebral malformation, 60.5% had LS intervertebral disk herniations, and 67.1% had abnormal tails; normal tail morphology was only identified in 32.9% of dogs. These results support an association between LS hemivertebrae at L7 and S1 and the degree of tail malformation and intervertebral disk herniation in English and French bulldogs. Tails were more consistently normal in pugs, and this breed exhibited more transitional LS vertebral malformations than hemivertebral malformations. All breeds had an increased incidence of intervertebral disk disease as age increased.

This study concluded that the severity of screw-tail in English and French bulldogs is correlated with the presence of hemivertebrae; pugs do not have true screw-tails and are more likely to have transitional vertebrae. In addition, apparently clinically normal pugs and English and French bulldogs can have vertebral abnormalities. Because these results were found in clinically normal dogs, the study authors caution against overinterpreting results of CT scans and emphasize the importance of lesion localization during neurologic examination to avoid intervening in a clinically normal patient. In addition, there were some limitations due to the study’s retrospective nature and the fact that most dogs did not undergo neurologic examination; it is possible that patients with intermittent or mild neurologic deficits were considered normal.


Key pearls to put into practice:


A genetic defect of the DVL2 gene that is linked to vertebral malformations of the thoracic and coccygeal vertebrae has been identified in English and French bulldogs.3 Pugs do not share this defect and therefore should not be considered to have true screw-tails. The tail defect in pugs is more likely vertebra curva, the result of bone bending from soft tissue tension during development.


The study findings further support minimizing severe screw-tails due to their correlation with vertebral malformations. Although patients may be clinically and neurologically normal, selective breeding to minimize the screw tail phenotype may improve the gene pool.


Although advanced imaging can be helpful for visualizing anatomic neurologic lesions, the physical examination, including a thorough neurologic examination, is the most important factor in determining the relevance of imaging findings. In some cases, findings could be consistent with normal aging and not be clinically problematic.


For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Clinician's Brief may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


Clinician's Brief:
The Podcast
Listen as host Alyssa Watson, DVM, talks with the authors of your favorite Clinician’s Brief articles. Dig deeper and explore the conversations behind the content here.
Clinician's Brief provides relevant diagnostic and treatment information for small animal practitioners. It has been ranked the #1 most essential publication by small animal veterinarians for 9 years.*

*2007-2017 PERQ and Essential Media Studies

© 2022 Educational Concepts, L.L.C. dba Brief Media ™ All Rights Reserved. Terms & Conditions | DMCA Copyright | Privacy Policy | Acceptable Use Policy