Judging from experience having had both cats and dogs? Lick my own butt. Probably spend a lot of time doing that.

Curl up and go to sleep somewhere, content at last

Lick my own junk.

Thank the fairy. Then go find a nice sunny spot and fall asleep. Unless it's winter then I'll go find a nice warm house

I mean, there's a lot to process here. It would depend, do I keep my present knowledge and intellect? Do I keep the abilities of the cat or dog? What about knowledge like how to hunt or eat? Why was I changed? What's the environment? Etc.

Could my wife adopt me as their new dog or cat or am I ostensibly a stray?

Would I still have human intelligence? Because if so, we're fixing to make a whole lot of money, without a whole lot of downside.

I'd scream "oh no!" so the wicked fairy wouldn't figure out it's fun for me and change their mind, and then I'd just chill with my dog or cat life. If I could be taken care of by a trusted person or people, that would be great.

Pick a nice family to live with, march into their house and have a happy life for the rest of my days as a spoiled pet.

What's wicked about her? Sounds like a pretty good offer, either way.

My wife is half fucking snow white. I'll be fine as either, but I'd prefer cat. Me and the current cat need to have a cat talk.

I remember reading a book when I was a kid called The Dog Days of Arthur Cane. I think the fairy was a witch doctor but basically the same idea. As I recall, Arthur saw the best and the worst of humanity during his predicament. Sadly no Wikipedia page for the author but the book is on Goodreads: https://www.goodreads.com/book/show/2006378.The_Dog_Days_of_Arthur_Cane

Sleep

I'd get more rest and leave all my debt behind.

Probably get hit by a car.

If i get to keep my intellect and memories, i'd just try to find a good owner and then enjoy it

I would woof or maybe meow...

Turn them into a mouse. Fair play, pixie. I'm counting to three.

Try to find a way back and as much about magic and the magical world as I can.

Bark or meow respectively.

Find a box and see what it's like to be in it.

Just be happy as a dog or a cat, probably look for a happy place where I'll be taken care of.

Maybe even do tricks nobody expects with my intelligence that's slightly superior to that of a normal dog or cat.

Shit on the pavement