Elevated anti‐Müllerian hormone in a stallion (Equus f. caballus) with terratoma and high inguinal testicle

Abstract This report describes a stallion presenting a unilateral high inguinal undescended testicle and a unilateral scrotal testicle teratoma. Blood tests showed increased levels of anti‐Müllerian hormone. Following castration, histological examination revealed that the teratoma contained testicular tissue, hair, hair bulbs, sebaceous glands, cartilage and endochondral bone. To our knowledge, this is the first study to report elevated anti‐Müllerian hormone levels in a stallion with both a teratoma and a high‐inguinal testicle.