Laparoscopic-assisted castration of a monorchid male pseudohermaphrodite pony

A pseudohermaphrodite possesses gonads of one sex, but with external genitalia of the opposite sex. Although cases of male pseudohermaphroditism have been published, there is no report of a monorchid male pseudohermaphrodite. This Case Report documents a 12-year-old monorchid male pseudohermaphrodite displaying stallion-like behaviour, with an elevated serum oestrone sulphate concentration confirming the presence of functional testicular tissue. A complete resolution of all behavioural signs occurred after laparoscopic-assisted castration under general anaesthesia, along with a drop in serum oestrone sulphate concentrations to <0.01 ng/ml and no response in serum testosterone concentration following administration of hCG.