In this study, the spinal nerves that constitute the lumbosacral plexus (LSP) were dissected in two species of South American wild canids (pampas fox-Pseudalopex gymnocercus, and crab-eating fox-Cerdocyon thous). The nerves origin and distribution in the pelvic limb were examined and compared with the LSP model of the dog described in the literature. The LSP was formed by whole ventral branches of L5 at L7 and S1, and a contribution of a one branch from S2, divided in three trunks. The trunk formed by union from L5-6 and S1 was divided into the cranial (cutaneus femoris lateralis nerve) medial (femoralis nerve) and lateral branches (obturatorius nerve). At the caudal part of the plexus, a thick branch, the ischiadicus plexus, was formed by contributions from L6-7 and S1-2. This root gives rise to the nerve branches which was disseminated to the pelvic limb (nerves gluteus cranial and gluteus caudal, cutaneus femoris caudalis and ischiadicus). The ischiadicus nerve was divided into fibularis communis and tibialis nerves. The tibialis nerve emits the cutaneus surae caudalis. The fibularis communis emits the cutaneus surae lateralis, fibularis superficialis and fibularis profundus. The pudendus nerve arises from S2 with contributions of one branch L7-S1 and one ramus of the cutaneus femoris lateralis. Still, one branch of S2 joins with S3 to form the rectales caudales nerve. These data provides an important anatomical knowledge of a two canid species of South American fauna, besides providing the effective surgical and clinical care of these animals. Anat Rec, 299:361-369,

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