"I mean, if I'm picking a dog breed so I can track a scent, why not go for the obvious choice?"
So you click "bloodhound" and then "apply changes". Then a little box shows up on the screen: "Warning! You have set your transformation to automatically revert after 6 hours. Make sure to be within near a Chronivac emitter at the appointed time. This device remains experimental and cannot guarantee a successful transformation beyond 20 feet as of this version (4.0 beta). Continue with present settings?"
You scoff at the warning message. "Of course I'll be back here in six hours. Where else would I be? In the pound? I think I'm smart enough to avoid that fate for less than half a day." You waste no time checking the box that says "Don't show this message again" before clicking "Yes."
A new message appears on the screen: "CONFIRMED! Your transformation will begin shortly and will revert 6:00:00 hours after completion. The change is estimated to take approx 2:00 minutes. Thank you for choosing TransDem!"
Your heart beats in anticipation, and it finally sinks in that you've actually just programmed a machine to change you into a fully nonhuman animal for the rest of the afternoon, and that it hasn't been tested at range, so you can't really afford too much of a delay in getting back to your apartment.
"Oh, shit, my apartment! How am I gonna get in and out of here as a canine?!" you think, but you remember the fire escape and open up the window that leads out onto the metal staircase. Hopefully no one will think a bloodhound galloping up and down it will be too weird. Just like before, you can feel the energy permeating your body and starting to tingle in places, but this time it isn't starting in your groin. This time, the tingling is starting in your ears. Both of your ears are tingling so much that you're moaning, and then they start to swell. You feel the lobes stretch longer and higher above your head, feeling heavier and heavier as they do so. Then that uncomfortable sensation of heaviness gets relieved in the strangest way possible when the tops sag down and flop against the sides of your neck. The ears are swelling larger and hanging even lower, when your inner ears POP and start bombarding you with louder and crisper sounds than you've ever heard in your life! It's overwhelming at first, and you reach up to cover your new ears, but you only manage to grope your giant bloodhound lobes instead.
"Agh! I guess I really underestimated getting dog ears. I was only really thinking about the nose! Oh well, I guess these will help too, I hope."
You lift a long brown earlobe up in front of your face to look at it and wonder what's next. You realize you can still feel the creepy tingling, but now it is surging up and down your spine. The tingling starts reaching further as your spine starts feeling longer. There is something jutting out from just above your butt. Immediately catching on to what's happening you pull down your pants in the back so your burgeoning body part doesn't end up painfully bunched up inside them. Sure enough, you can see a muscular mound forming and growing longer, curving out a bit as it starts rivaling the length of your legs, and surprising you a bit when you feel it start to move. You aren't sure you really needed all this just to find where a box came from.
But you're stuck with your tail for six hours, and it starts to feel more natural for you to be wagging it, and you realize you'd better get out of your other clothes until you need them again. The tingling moves to your groin, and this time you look down to see your dick getting swallowed up by a sheath that has fused to your belly! It swells up in strange-looking ways inside there, and suddenly you are even more glad that this transformation is time limited. No, this is not as emasculating as watching it turn into an udder, but it is kind of disconcerting to lose your familiar manhood for the second time in just a few minutes. "Just six hours," you tell yourself again.
Your arms and legs start to tingle, and you have to face the fact that you'll have to do this little investigation without hands. Your upper arms and things start to shrink, making you unsteady and toppling you to all fours pretty early in the process. Your feet start to stretch, lifting your ankles off the ground, while your toes thicken up and sprout claws. You get a pretty close up view of your thumbs shrinking away until nothing is left of them but dewclaws, which feels extremely limiting even in comparison to your hands thinning out and your fingers distorting. Soon you've got nothing but clawed toes at the ends of your forelimbs as well. At least the pads forming at the bottoms make it slightly more comfortable to stand like this.
The tingling spreads over your skin, and brown fur sprouts from head to tail. The final change, the one you've been waiting for, builds up in your face like a balloon waiting to pop. A great shelf of bone creaks its way forward, taking your mouth and nose with it and lining them up with each other. Fresh air fills your gaping nasal cavities and brings in the scents around you more intensely. Your long, tall snout gets bigger and finishes up with a darker and wetter pair of nostrils than you had before. A tingling inside your great muzzle makes the smells easier and easier to detect until there are more of them than ever and they are almost impossible to ignore. You breathe in through your nose and almost fall over. But this is what you wanted, so you sniff experimentally and cope with the sensitivity as best you can.
The Chronivac DINGS loudly in your larger ears, and a timer pops up on the screen. 06:00:00, 05:59:59, 05:59:58, 05:59:57 ...
Okay, it's time to do this. You've got the body to track down whoever left you the package, but you'd really be wise to be back here when that timer gets down to 00:00:00.