Feeling the girl under him clench down on his cock and orgasm from him fucking her, he lets out a loud growl. His shaft pushed deep inside of her, no way the human girl could take the knot, he starts to orgasm. Warm, thick cum begins to pour into her body, flooding her womb and cunt with his cum until it was squirting out around his shaft.
The changes wouldn't take too terribly long. As he pulls his dick from her pussy, she'd begun. First, the fur. Warm, silky red and white fur over her body, from her toes all the way up. Then her ears, long pointed ears of a fox. Her muzzle was last, until she was like him, except ever the vixen.