A Proposed Radiographic Classification Scheme for Congenital Thoracic Vertebral Malformations in Brachycephalic “Screw‐tailed” Dog Breeds

Abstract

Congenital vertebral malformations are common in brachycephalic "screw-tailed" dog breeds such as French bulldogs, English bulldogs, Boston terriers, and pugs. The aim of this retrospective study was to determine whether a radiographic classification scheme developed for use in humans would be feasible for use in these dog breeds. Inclusion criteria were hospital admission between September 2009 and April 2013, neurologic examination findings available, diagnostic quality lateral and ventro-dorsal digital radiographs of the thoracic vertebral column, and at least one congenital vertebral malformation. Radiographs were retrieved and interpreted by two observers who were unaware of neurologic status. Vertebral malformations were classified based on a classification scheme modified from a previous human study and a consensus of both observers. Twenty-eight dogs met inclusion criteria (12 with neurologic deficits, 16 with no neurologic deficits). Congenital vertebral malformations affected 85/362 (23.5%) of thoracic vertebrae. Vertebral body formation defects were the most common (butterfly vertebrae 6.6%, ventral wedge-shaped vertebrae 5.5%, dorsal hemivertebrae 0.8%, and dorso-lateral hemivertebrae 0.5%). No lateral hemivertebrae or lateral wedge-shaped vertebrae were identified. The T7 vertebra was the most commonly affected (11/28 dogs), followed by T8 (8/28 dogs) and T12 (8/28 dogs). The number and type of vertebral malformations differed between groups (P = 0.01). Based on MRI, dorsal, and dorso-lateral hemivertebrae were the cause of spinal cord compression in 5/12 (41.6%) of dogs with neurologic deficits. Findings indicated that a modified human radiographic classification system of vertebral malformations is feasible for use in future studies of brachycephalic "screw-tailed" dogs.

Vertebral Malformations in French Bulldogs

“…A total of 43 abnormal vertebrae were in the thoracic spine, from which there were 33 hemivertebrae which represent 49.25% from all abnormal vertebrae, and 75% of all hemivertebrae found in this study. The most commonly affected vertebrae were Th8 and Th10 which is similar to previously published studies (Aikawa et al, 2007;Berlanda et al, 2011;Charalambous et al, 2014;Gutierrez-Quintana et al, 2014), although we did not prove that these anomalies are concentrated on any particular vertebra of the thoracic segment. To predict the occurrence of clinical symptoms, we cannot rely only on the occurrence of hemivertebrae in the thoracic spine.…”

Congenital and acquired anomalies of the caudal vertebrae in dogs: Radiographic classification and prevalence evaluation

“…A high number of congenital pathologies, in the form of multiple hemivertebra and block vertebra, have been documented (Done et al, 1975;Gutierrez-Quintana et al, 2014). The aim of the present study was to determine the prevalence of anomalies in breeds for which the presence of congenital anomalies in the caudal vertebrae is not typical.…”

“…1968; Newitt et al, 2008;Gutierrez-Quintana et al, 2014;Mäkitaipale et al, 2015;Proks et al, 2015). Many anomalies, both in terms of type and number, are explained by the manner in which vertebral bodies form (Morgan, 1968).…”

Late‐onset wedge‐shaped thoracic vertebrae in a six‐month‐old pug

“…The trapezoid or triangular shape of the hemivertebral bodies implies that the force that is normally predominantly rostrocaudally directed along the vertebral column will be more greatly diverted into a dorsally directed vector, which causes either affected or neighbouring vertebral bodies to be displaced dorsally during bone growth (Jeffery and others 2007). According to Gutierrez-Quintana and others (2014), intervertebral instability between the normal and malformed vertebrae may result in damage to the intervertebral disc and predisposes it to herniation, as in this case. Another study demonstrates that kyphoscoliosis significantly accelerates intervertebral disc degeneration in adjacent intervertebral disc spaces in dogs (Faller and others 2014).…”

“…As a result, the defect can be latent until the ossification of the vertebrae is more advanced or complete (nine months) (Wright 1979). The most commonly affected site is the mid-thoracic region (T5–T9) (Done and others 1975, Moissonnier and others 2011, Faller and others 2014, Gutierrez-Quintana and others 2014). Instability of the vertebral column, progressive vertebral stenosis and clinical symptoms such as kyphotic or scoliotic angulation of the vertebral column may appear between four and nine months of age when the most dramatic and rapid curvatures may be seen during periods of accelerated growth (Wright 1979, Schlensker and Distl 2013).…”