Update on the anatomy of the brachial plexus in dogs: Body weight correlation and contralateral comparison in a cadaveric study

A thorough knowledge of the anatomy of the brachial plexus is pivotal for diagnostic, therapeutic and anaesthetic purposes in order to correctly locate the nerve and reduce the incidence of complications when performing surgery or a local anaesthetic block of the brachial plexus. In this study, the anatomy of the brachial plexus in dogs was reviewed; the depth and diameter of each nerve were evaluated, and the contralateral limbs were compared. Eighteen canine cadavers were included and were divided into: small (SB); medium (MB) and large (LB) breed dogs. After dissection, the spinal roots and the suprascapular, subscapular, axillary, radial, ulnar, median, and musculocutaneous nerves were identified. The following evaluations were recorded: the origin of the nerves from the spinal roots, the roots and the nerve diameters, and the distance of the nerves root from the skin at the level of the scapula-humeral joint and from the interscapular region. A total of thirty-six brachial plexuses were evaluated; all originated from the ventral rami of the C6 to T1 spinal nerves. In the LB dogs, the root and the nerve diameters were larger as compared with the other two groups. In this group, also the mean distance of T1 from the skin at the level of the scapula-humeral joint and the average distance of the nerve roots from the skin of the interscapular region were also greater as compared with the other groups. No significant differences were recorded between the contralateral limbs. In the dogs in the present study, the origin of the nerves of the brachial plexus were similar to those previously reported; however, the presence of minor individual variations was confirmed between the right and the left limbs within the same dog between the right and the left limb. This is the first time that the diameters and the depth of the nerves have been described and positively correlated with body weight.