"Nothing ventured, nothing gained!" you say to yourself, setting the transformation into "full-body canine." Had you actually experimented with the device a little more before hatching this ridiculous scheme, you would have found the "alter reality" setting which could do marvelous things like stop anyone from questioning the sight of a human with a dog's nose. As it is, you are more worried about looking like a freak than possibly getting put into the pound.
"I'll probably be fine," you think. "I only need to be a dog long enough to track down the origin of the box. Surely I can make it as a dog for that long! Wouldn't it be easier to be a dog than answer questions about why I'm sniffing the ground as a human?"
Besides, it's not as though the feline option wouldn't come with risks of its own. What if you got chased by a dog? What if you got eaten by a wild animal? Besides, a stray cat get picked up by animal control almost as easily as a dog. If you're turning into turn yourself totally into an animal just to track a scent, you might as well get the benefit of having multiple drastically different breeds to choose from!
Of course, you still have to decide how long to actually stay as a dog. The longer you wait to change back, the more likely it will be for something to go wrong that you can't fix while you're not a human. The sooner you change back, though, the more likely it will be for you to run out of time before you've both found the box and safely returned home. Maybe six hours would be good? That's should be plenty of time to follow the scent trail even if it's all the way across town and back. You probably won't need nearly that much time, and then you can just relax at your house as a canine until you change back for the next phase of your investigation!
Of course, it does take you a while to scroll through all the options, since you hadn't fully expected just HOW MANY different breeds you would have to choose from. It's not too difficult a choice, though, once you find the one you're looking for. You're obviously going to turn into a ...