As Dan found himself becoming an exceptionally horny Minotaur heifer, she felt an ugre to give Kat something she would need, as well deserved.
Oddly her insatible and growing sensation for lust was making and twisting the spell Kat placed over her brother.
Screams of an inhuman kind turned to bellowing Mooing sounds as Dan felt herself slipping, the transformation was not complete yet. It would come to an end, once Dan had herself standing on all four, swinging a boney tail, and feeling it begin, she gave Kat her present.
Still in the house, and before his evil minded sister, Dan lifted her tail, depositing a four pound mound of stench upon the floor.
Once done, Dan mooed at his sister, almost laughing in a cowish way.