Constancia Island by Chris Bellows

Constancia Island, an exclusive Caribbean paradise is a sovereign country designed exclusively for the institution of Female Domination and male submission... where troubled young males, at one time destined for lives of crime, are treated as beasts of burden, pony-boys, not only for the amusement of the island's defacto queen, Lady Constance, but as the island's sole method of conveyance for visitors and residents alike.

Lady Constance is assisted in her endeavors by well-trained female descendants of a curious African tribe whose disdain for the male gender becomes the basis for the female hierarchy on the island. Everything at the island has been built and acquired to keep the male beast well-exercised, chaste and servile. Major-domo to Lady Constance, Jasmine, properly trains the submissives, and assists Dr. Reinhold in the ultimate medical modification of the male to keep them subservient, randy and eager to serve their Mistress in any way she desires.

This Fem/dom novel has strong elements of both physical and psychological male submission, humiliation, pony play, oral sex, anal sex by way of strap-on, chastity and denial, bladder control, body modification, and discipline with whips canes and suspension.