Teratoma Associated With Testicular Tissue in a Female-Like Horse With 64,XY (SRY-Positive) Disorder of Sex Development.

A four-year-old female-like Quarter Horse was admitted for clinical evaluation because of masculinized-aggressive behavior and lack of estrous signs. On external inspection, a hypertrophied clitoris and prominent muscles were observed. On gynecological examination, apparently normal mammary glands, vulva, vagina, and cervix were noted.