You are finally able to convince yourself to leave the dog behind but he doesn't seem to be quite as willing. When you turn to leave he jumps on top of you and knocks to you to the ground.
As you get up the dog gets on top of you while your in a kneeling position and it enters through your ass. You gasp in pain as the dog begins to hump. It feels weird and unnatural but an even weirder feeling grabs your attention as you look down at you torso. Under your original pair 6 more sets of nipples form and all 8 inflate into miniture breasts.
You look down as your penis shrinks and finaly disapears inside yor body. Your ass splits in two and the part still containing the dog's cock, shifts to where a bitch's vagina would be.
The dog's mounting no longer feels uncomfortable to you but rather enjoyable as you forget about your human worries. You feel as your ears come to points and your teeth sharpen but don't seem to care. You wait and the gigantic dog finally spills its seed inside of you.