"Ahhh, I see you have two twin brothers, Chad and Tad. Well I'll be paying them a visit. You hang tight boy, I'll be back."
The man leaves you there struggling in your bonds. You feel extreme pain as your insides melts and re-form, your skeleton reshaping itself. You feel your wrists become small enough to slip through the cuffs holding you on the table. You try in vain to use them to free yourself, but they just feel weird. Finally you raise them to your face and see they look almost exactly like a dog's paws. This can't be happening! You try to scream, but your voice hardly works, your vocal chords changing. Finally your legs change forcing you down onto the ground on all fours. Fur now covers your entire body. Your teeth grow in size, your face stretching out into a muzzle. Finally your voice comes back but instead of screams you let out mad barking and whines like the dog your are. A tail pushes out of your butt, then begins wagging and sprouting hair.Last of all you feel something very odd in your crotch, you bend your canine head down and see your dick shrinking back into a furry sheath which connects to your waist, as your balls are covered in hair. Your doggy dick seems larger than your human one, and your balls swell with canine seed.
Standing there, you suddenly stop freaking out. Its like for a second you forget why you were so worried. Then you remember, you're not supposed to be a frickin dog! Or...are you? Somehow you get the feeling you used to be human, but clearly you're not now. Somehow all your human memories become so distant, so far away. Like you're just aware of them. You don't recognize the human who is the star of all your memories as yourself. Finally your mind is reduced to that of a simple dog. You're aware of those human memories, but they don't worry you any more. You've been a good dog your whole life.
You walk around the room sniffing it, exploring your new surroundings. Your canine nose can pick up and sort out odors on a level far above that of a human. You find some clothes in the room that smell like you as a human, the smell is familiar and confusing, because you're not human and never have been. Finally after a few hours you hear voices coming from outside the room. You see two men coming in, dragging a young man each. The two young men appear to be early 20-something, and the two men carrying them place them each on a table and tie them down like you were. These two seem familiar somehow, then you recognize them from all those weird memories of human you have. You know those three humans are brothers, but aren't sure how they're related to you.
After they're both tied down the new guy looks at you and smiles. nodding to the other human and saying something about a physical examination. You can't really get it all, your canine brain unable to register complex speech. Then the new guy, who is dressed in blue jeans and a red t-shirt places a collar around your neck and then pulls you into another room. As you look back you see the two boys coming around and getting injected with needles...