XX sex reversal in a llama.

A 5-month-old llama was examined for evaluation of sexually ambiguous external genitalia. To determine the phenotypic, chromosomal, and gonadal sex of the llama, transrectal palpation and ultrasonography, contrast cystography, karyotype evaluation, laparoscopy, and necropsy were performed. A karyotype of 74,XX and finding of components of the müllerian duct system were suggestive of a female phenotype and chromosomal sex. On histologic evaluation, however, components of the wolffian duct system also were found, and the gonads were composed entirely of testicular tissue. The diagnosis was XX sex reversal, with a XX male phenotype.