As Kate's words sank in, Matt was left thinking what animal he could stand to be for the rest of the days, especially if he could choose. His mind went to a pasture and a large, gallant steed with a white mane and massive body. While he thought, Kate was the first to notice the rather sizeable bulge growing in Matt's pants; both in front and behind.
"Oh god, this can't be happening," Tom said in shock as the front of Matt's sweatpants burst open as the pressure was too much. Out unfurled a nearly thirteen inch, half-mottled and half-human cock hung from a sheath that was growing up his bulking torso. That his balls were swelling with activity, darkening and sprouting coarse hairs all over.
"I feel so hot," was Matt's only comment as his ass joined in destroying the remnants of Matt's pants and underwear, it gained weight and sprouting a tail quickly.
"You are coming along nicely," Kate commented as Matt's thighs and hips grew larger. They stiffness in them was a struggle for Matt to fight on two feet but as his socks burst to reveal his toes now most hoof, it seemed pointless to resist. Falling to his hands, he only noticed that they to were merging and darkening into thick hoof.
"Ohhhh," Matt moaned as his face started to stretch. His nostrils flared hot as his teeth tumbled out to make way for the new equine ones. "It... feel.. arrahHHH," were Matt's last strained words as his face became more horse than man. His mane was sprouting and all over, his body was gaining muscle and girth. Speaking of, the massive member was now definitively equine and almost bordering on massive as is hung beneath is ever growing belly.
Meanwhile, Tom could only watch and Kate slipped behind him. "Seems your friend chose something rather big. So what'll be your pick? I'd decide soon because Matt looks mighty horny right now, and he knows you've still got a change in you. So what, will, it, be?" she said in his ear, sending a shiver down his spine.