It wasn't just his cock that was growing, it was his entire body. Muscles swelled under his skin while a fine coat of brown fur sprouted ontop. He was almost too deep in ecstasy to notice, certainly deep enough in Ty's little pussy.
"Nyaaa! K-keith-san pleeease, I'm not a girl I promise!!" she babbled in japanese to his pleased ears, which were relocating to the top of his head, going long and fuzzy. He grunted, "Ooooh god you are tight! Are you getting tighter on me slut?" He hardly realized that it was actually his cock swelling out to horse size, going blunt at the tip and flaring against the back of her tunnel. The force actually pushed Ty forward onto the couch, her arms could barely stop her swollen tits from smooshing against the sofa cushions. A thought crossed Ty's mind, that if she ever got back into her old body, or even just got her power back, she would make Lizzie pay for this.
Keith's proportions kept growing, his face pulled into a blunted horse muzzle, but only the slightest of concern overcame him, his feet starting to click against the floor as they meld into hooves. The anthrofied horse-man pushed one of his huge thumbs against her tailhole, and he was all to tempted to drive his enhanced equipment into her hot little pussy, even though only about half of him fit...those musky, massive horse balls swayed as they filled with cum, churning and ready for release. Ty, however, was panting and frustrated, unable to bear that thick monster in her stretched little pussy, her poor clitoris was even forced to rub on his dick-flesh from the penetration alone. Every thrust was wave after wave of pain and pleasure, ping-ponging her back and forth. Her heart was thumping in her chest, almost in rhythm with her bouncing and jiggling tits. Ty's tender nipples ached and rubbed even against the soft fabric of her T-shirt.
Keith was now fully aware of his equine-ness, but if anything it seemed to just spur him on. He grabbed her by the hips and pushed hard, feeling himself bottom-out on her. "Mmm...I wish I could get this all the way into you little kitty, make you mine..." Just then her thighs began to quiver, and along with her hips and ass they all start to grow underneath his hands. Keith was surprised, but as his dick began to sink deeper and deeper into her he understood what was happening. Her body continued to reshape to suit him, her pussy staying tight around his thickness as she grows new depths for him. Still his thrusts bottom out, and she howls in pain and pleasure as he rubs her cervix and her O-spot over and over, her G-spot well taken care of by his mid-length ridge. It was all too perfect, and Keith couldn't last long under all that pleasure. He sharply grunted and sprayed cum into her.