Comparative Neuroanatomy of Terminal Spinal Cord Malformations in Pigs with Perosomus elumbis and Human Caudal Regression Syndrome

Congenital caudal malformations in domestic animals are traditionally reported as Perosomus elumbis (PE), but the associated spinal cord abnormalities are poorly characterised. This retrospective cadaveric study describes the terminal spinal cord in five neonatal pigs with severe caudal malformations, comparing the findings with published MRI descriptions of human caudal regression syndrome (CRS). Four formalin-fixed specimens (P1–P4) underwent radiography, CT and MRI, followed by dissection of the pelvic and visceral organs. One historical specimen (P5) was examined by dissection only. Spinal cord findings in P1–P4 were based on MRI, without histological confirmation. The three pigs with complete lumbosacrococcygeal agenesis had a high termination of the spinal cord (T12–T15). This termination was apparently abrupt (P1), bulbous (P3) or elongated and rod-shaped (P2). In P2, the dural sac containing the terminal spinal cord protruded through a skin-covered vertebral defect. The two pigs that retained lumbar or sacral segments showed a more caudal termination, tapering at L3 (P4) or at S1 with skin-covered lumbosacral dysraphism (P5). Paired fluid-signal structures, provisionally interpreted as nerve-root sleeves, were observed in P3 and P4. These patterns show morphological similarities with human CRS. MRI complements previous radiographic, CT and pathological descriptions by characterising the terminal neuraxis.