Investigation of Sciatic Nerve Surgical Anatomy in Dogs and Cats: A Comparative Cadaveric Study

Objective: Dogs and cats with traumatic or iatrogenic partial sciatic nerve lesions frequently have disparate clinical signs. Cats commonly walk with a plantigrade posture in the affected pelvic limb, which is rarely observed in dogs. We hypothesized that the tibial nerve would be localized more laterally in cats and medially in dogs, and that the tibial nerve would be larger than the peroneal nerve in cats, which may result in a greater susceptibility of the tibial nerve to iatrogenic trauma in cats. Goal of the present cadaveric study was to investigate differences present in pelvic sciatic nerve anatomy between dogs and cats. Methods: This is an anatomic cadaveric study. Dogs (n=7) and cats (n=7); n=28 hindlimbs. A simple suture was placed without nerve mobilization on the lateral aspect of the lumbosacral trunk at the level of the mid-body of the ilium. A caudolateral approach to the femur was then performed. The lumbosacral trunk was transected in the intrapelvic area cranial to the suture marking the lateral aspect. The peroneal and tibial branches of the sciatic nerve were separated. The proximal lateral knot was identified as being part of the tibial or peroneal nerve, respectively, and the diameter of the tibial and peroneal branches at the level of the suture (mid-ilium) were measured. Results: No difference in relative size of the tibial compared to the peroneal nerve was found between dogs and cats. The tibial nerve was not found to be localized lateral to the peroneal nerve more frequently in cats compared to dogs. Conclusions: Findings suggest that the intrapelvic anatomy of the lumbosacral trunk cannot fully explain the plantigrade posture observed in cats with traumatic or iatrogenic partial sciatic nerve injury.