Computed Tomography Appearance and Characteristics of Presumptively Normal Brachial Plexus in Dogs

Little information concerning the CT characteristics of the canine brachial plexus is available. This study aimed to describe size measurements and CT characteristics of the brachial plexus in dogs and explore correlations with patient characteristics to provide clinical interpretation guidelines. A retrospective analysis of 39 thoracic CT studies categorized dogs by weight and breed type (chondrodystrophic/non-chondrodystrophic). The brachial plexus was evaluated at a defined anatomical location in the axillary region, with measurements recorded for size (cross-sectional area, height, and width), attenuation (HU), subjective conspicuity, and the amount of interlying fat tissue. A strong positive correlation was found between dog weight and all brachial plexus size measurements (p < 0.0001). Intra- and interrater reliability of size measurements was moderate to excellent (ICC 0.74-0.92 and 0.77-0.99, respectively), but those with the highest reliability lacked absolute consistency (large standard error of measurement). Age was negatively correlated with size, but this association was confounded by weight. Neither laterality, sex, nor breed type significantly affected size or attenuation. The subjectively estimated amount of interlying fat was significantly associated with minimum precontrast attenuation values and the conspicuity of the brachial plexus, with dogs having more fat showing a blurred plexus appearance. No difference was found for the characteristics of the brachial plexus when evaluating chondrodystrophic breed-type dogs compared to non-chondrodystrophic ones. These descriptive characteristics, stratified by weight, provide valuable guidelines for clinical interpretation of the presumed normal canine brachial plexus on CT.