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New Study Reveals Common but Underdiagnosed Spinal Anomaly in Cats
Frontiers in Veterinary Science 2025
Obi Veterinary Education
September 30, 2025
Q. Van Koulil, K. M. Santifort, D. S. Willems, G. Bolen, S. De Decker, M. Bernardini, N. Bergknut, I. Van Soens
Background
Congenital vertebral malformations in cats are less frequently described than in dogs. Vertebral vascular canal dysplasia (VVCD), previously identified in brachycephalic dogs, involves defects in vertebral body ossification centered around the vascular canal. This study aimed to describe VVCD in cats using CT and MRI imaging, apply a canine-derived scoring system, and assess inter- and intra-observer agreement. The authors hypothesized that VVCD would be less prevalent in cats than dogs and frequently incidental.
Methods
This multicenter, retrospective observational study evaluated 2,037 cats who underwent CT or MRI imaging of the thoracic vertebral column between 2018–2023. Cats with at least one VVCD-affected vertebra were included. A previously developed canine scoring system classified the severity (A: <50% VBH, B: 50–<100% VBH, C: 100% VBH) and canal shape (single, double, complex). Agreement among observers was assessed using Cohen’s kappa under four scoring scenarios varying in complexity.
Results
VVCD was found in 541 cats (26.6%). The most affected breed was Domestic Shorthair (50%), and males were slightly overrepresented (57.7%). The mean age at imaging was 90.1 months. CT was the primary imaging modality (94%). The sixth thoracic vertebra (T6) was most commonly affected, though cervical and lumbar vertebrae were also involved. Intra-observer agreement ranged from moderate to perfect (κ = 0.543–1.000), while inter-observer agreement was more variable (κ = 0.225–0.894), improving in simplified scoring scenarios. The most consistent agreement was found when canal morphology was excluded.
Limitations
The study was retrospective and used non-standardized imaging protocols, leading to variability in image quality. MRI evaluations were limited by missing transverse views and non-uniform sequences. The scoring system, adapted from canine models, proved subjective, especially in differentiating mild VVCD from normal variants. Additionally, clinical indications for imaging were not uniformly available, limiting evaluation of clinical relevance.
Conclusions
VVCD appears to be a relatively frequent incidental finding in feline thoracic imaging studies but occurs less commonly than in brachycephalic dogs. Although the adapted scoring system is a useful diagnostic tool, it requires refinement to enhance reliability. Future prospective studies with standardized protocols and normal anatomical baselines are necessary to clarify the clinical relevance and pathophysiology of VVCD in cats.
Transverse CT images of different vertebrae (in bone window) showing examples of the different vertebral vascular canal dysplasia (VVCD) grades, based on the scoring system of Santifort et al. 2022. The first letter defined the height of the affected vertebral body. Score A = max. 50% of the vertebral body height (VBH), B = 50 - < 100% of VBH, C = complete (100% of VBH). The second letter described the shape of canal: s = single (midline or unilateral), d = double (bilateral), or c = complex (double and converging to single or deviating in shape).
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