Morphology of a six-legged goat with duplication of the intestinal, lower urinary, and genital tracts.

Background: An adult female goat with rare malformations, which consisted of duplication of the intestinal, lower urinary, and genital tracts as well a pair of parasitic appendages, is presented.

Methods: A complete dissection was performed on a moribund female goat (Capra hircus).

Results: The animal had a normal body with a parasitic attachment located within the pelvic region. This attachment was represented by an ovoid, trunk-like, adipose mass that lacked internal organs or vertebrae but that had two fairly well-developed limbs with the normal components of hind limbs. There was duplication involving the external and internal genitalia, the urethra, the urinary bladder, and portions of the small intestine as well as the large bowel, including the anal openings.

Conclusions: An autosite with a duplication involving the hindgut and paramesonephric anlages was identified. These features were compatible with life in utero and postutero and emanated from incomplete twinning (heteropagus twins). A review of the literature also suggests that heteropagus twins are a very rare abnormality in both domestic animals and humans.