The other subject looks at you and says, "You can choose the species if I get to be male." He didn't know it, but you had always wanted to be a girl, but you were to scared to come out as trans so you accepted his offer.
As the doctor came back in and asked what the decision was, you said, "I will be a female red wolf". You had always adored that animal so it was fitting.
" Perfect choice!", said the doctor enthusiasticly as he stuck a needle you didn't see him come in with into your left shoulder. He preceded to stick a different neadle into your soon to be mate.
The doctor told you to take off your clothes and you complied. Suddenly you felt dizzy and tripped onto the floor. When you tried to stand up, you couldn't seem to get your body to move like that. You felt the fur spread arrest your body and then felt a searing pain in your face as your nose and mouth pushed out into a muzzle while your ears became pointed and moved to the top of your head. You thought the muzzle was slightly longer proportionally than a grey wolves muzzle and your ears felt longer too. Then your skull shifted and your eyes became golden coloured. Your head was completely a red wolf. You passed out for a bit s the rest of you instantly shifted into what appeared to be a mix of a coyote and a wolf. But that pain was nothing like what was to come.
The doctor came back out with a second needle but only used it on you. You felt like someone had taken a shotgun to your genitals as your penis and balls shot back into you turning into their female equivalents and you felt your internal organs shift around to become fully female. After all that intense shifting, you passed out.