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 study describes the terminal spinal cord in five pigs with severe caudal malformations, comparing the findings with those of human caudal regression syndrome (CRS). Four formalin-fixed specimens (P1–P4) underwent radiography, computed tomography (CT) and magnetic resonance imaging (MRI); one specimen (P5) was examined by anatomical dissection. All cases showed terminal spinal cord anomalies. The three pigs with complete lumbosacrococcygeal agenesis (P1–P3) had a high spinal cord termination at T12–T15. This resembled Pang group 1 of human CRS, and was either abrupt (P1) or with a bulbous end (P3), or elongated and rod-shaped (P2). In P2, the spinal cord and dural sac protruded through a vertebral closure defect covered by skin, which is suggestive of tethering. The two pigs that retained lumbar or sacral segments had lesions that were located more caudally: a gradually tapering termination at L3 (P4) and lumbosacral spinal dysraphism (P5). In P3 and P4, caudally projecting structures were interpreted as cerebrospinal fluid (CSF)-filled sleeves around paired nerve roots. Four pigs exhibited a Buddha-like posture of the pelvic limbs. This is the first MRI-based description of terminal spinal cord anomalies in porcine PE, supporting a comparative neuroanatomical approach to these malformations.