You’ll be able to see all your pets by pressing on the special Pet button next to your avatar name. If you have no pets equipped, it will show a paw print. If you have an active pet, it will show a small pet avatar. 

When you press on the pet button, if there is no pet equipped, you will open up the Pet Hotel, where you will be able to see all your pets, and choose which pet you want active with you in the game. 

If you have a pet activated, then pressing on the button will open up your pets Pet Page.