The equivalent of castration for female animals is spaying. The term castration is sometimes also used to refer to the removal of the ovaries in the female, otherwise known as an oophorectomy, or the removal of internal testes, otherwise known as gonadectomy. Surgical castration in animals is often called neutering. Castration causes sterilization (preventing the castrated person or animal from reproducing) it also greatly reduces the production of hormones, such as testosterone and estrogen. Surgical castration is bilateral orchiectomy (excision of both testicles), while chemical castration uses pharmaceutical drugs to deactivate the testes. Castration is any action, surgical, chemical, or otherwise, by which an individual loses use of the testicles: the male gonad.