Persistent cloaca and caudal spinal agenesis in calves: three cases.

Three newborn calves were affected by caudal spinal dysgenesis or agenesis (coccygeal vertebra) and persistent cloaca. The cloacas were lined by a mixture of transitional and colonic epithelium. The vertebral column of one calf was internalized into the cloaca. The association of persistent cloaca and caudal spinal anomalies is thought to be related to cell loss in the caudal cell mass, which affects caudal spinal column formation and cleavage of the cloaca by the urorectal septum. This association is well documented in humans and has been reported in Manx cats. By extrapolation, it appears likely to exist also in neonatal calves. Identification of cloacal lesions in neonatal animals should be cause for careful examination of the vertebral column because many of the associated spinal lesions are occult.