Incomplete Caudal Duplication With Correction of Pygomelia in a Dog

Congenital malformations are structural defects that occur in all species during fetal development. Pygomelia is a type of polymelia in which the redundant legs are joined to the pelvis. This abnormality is observed in both human beings and animals. A mixed female (Shih Tzu) puppy with a rigid mass resembling two pelvic hindlimbs was referred to a pet clinic in Mashhad City, Iran. In radiographic assessments, two extra hindlimbs stemmed from malformed pelvic bones and were shorter than normal limbs. Both extra acetabula were detected on the hemipelvis, with two extra coxofemoral joints perpendicular to the regular hip joints in the caudal direction. Also, two vulvas and two anuses were seen, but only one vulva and anus were functional. The additional limbs were amputated by surgery. This case is the first report of a dog with incomplete caudal duplication and successful correction of pygomelia in Iran.