From atlas to sacrum: Morphological and morphometric characterization of the feline vertebral canal using computed tomography

The vertebral canal plays a critical role in protecting the spinal cord and maintaining biomechanical stability. Although the vertebral canal has been extensively studied in dogs, equivalent analyses in cats are limited. This study provides a comprehensive morphological and morphometric assessment of the feline vertebral canal from atlas (C1) to sacrum (Sc) using computed tomography (CT). In 35 cats, predominantly European Shorthairs, cross-sectional area (CSA) and perimeter (P) were determined at cranial, central, and caudal levels of each vertebra. Vertebral canal circularity (CVC) was calculated to characterize shape and intersegmental angles (ISA) were measured to quantify spinal curvatures. Additionally, sex- and age-related differences were examined. Male cats exhibited significantly larger CSA and P than females, whereas CVC was mostly unaffected by sex. CVC was highest at C3 (cervical), Th6 (thoracic) and L4 (lumbar) and lowest at C1, Th1, Th13/L1 and the sacrum, reflecting shape variations at spinal transition zones. CSA and P were strongly correlated. Cats older than 10 years showed increased CSA and P compared with younger individuals, accompanied by decreased CVC at multiple levels, suggesting age-related remodeling. ISA largely corresponded with physiological spinal curvatures described in the literature. This study presents the first CT-based morphological and morphometric characterization of the feline vertebral canal spanning C1 to Sc. The data provide fundamental reference values for diagnostic imaging and comparative anatomy, suggesting vertebral canal shape, besides its dimensions, as a potential factor in the context of feline spinal pathology.