Unusual Incidence and Location of Renaut Bodies in Beagle Dogs in a Nonclinical Study

We identified the presence of Renaut bodies in an unusual location in Beagle dogs on a 3-month nonclinical toxicity study. These peculiar structures are commonly reported as a background finding in the sciatic nerve of dogs. In our study, however, they were also observed in autonomic nerves surrounding the adrenal gland, a location in which they have not been reported before. The incidence in both locations were 8 of 32 Beagle dogs in the sciatic nerve and 6 of 40 Beagle dogs around the adrenal gland in the dosing and/or recovery phases of the study.

Case Report: Canine Strain– and Study Condition–Dependent Formation of Renaut Bodies in Sciatic Nerves of Beagle Dogs

Two beagle dog strains were used in a 14-day intrathecal infusion study for a small molecule test article. A moderate number of Renaut bodies (RBs) were observed in the sciatic nerves of control and test article–treated adult animals as early as 1 day after test article infusion (ie, 5 days after catheter implantation in the lumbar cistern). In most cases, the sciatic nerve was affected unilaterally, apparently in association with extended lateral recumbency on one side. The lighter beagle strain (Marshall), and especially the females (which weighed less than age-matched Marshall males), developed more RBs. In contrast, neither females nor males of the larger strain (Harlan) developed any nerve lesions. These data support the hypothesis that RBs develop following mechanical stress to sciatic nerves, suggest that this change may develop fairly quickly following an insult, and demonstrate that different dog strains exhibit strain-specific nerve changes.

Microscopic Anatomy of the Posterior Interosseous and Median Nerves at Sites of Potential Entrapment in the Forearm

We describe the macroscopic and microscopic anatomy of the posterior interosseous (PIN) and median nerves, at the arcade of Frohse and pronator arch respectively, in nerves obtained from five cadavers. Nerves were either constricted at sites of potential entrapment; appeared swollen proximal to these sites; or exhibited neither swelling nor constriction. Renaut bodies were present in all nerves. In the PIN, most Renaut bodies were found beneath a tendinous arcade of Frohse, whereas in the median nerve most were found proximal to the pronator arch. We propose that since Renaut bodies appear to displace normal endoneurial components, and may be associated with low-grade axonal drop-out, their presence may adversely affect the functional outcome of surgical decompression of either the PIN or median nerve.