Ya'll need to keep in mind she's an 11 year old girl in the flashback, who doesn't have her memories of her previous life yet. She's probably assuming the "dog" will be smart enough to know where her house is so they can play together. And well, she brought him cake cause that's probably what she'd want to eat if she was hungry, as most kids don't know what animals can and cannot eat, they'd resort to the "I like this, so they'll like this" kind of thought. Luckily for her, this "dog" is a person that transforms into an animal, so just eating w/e is fine for him. Some kids also don't care for shit like dog saliva germs. I mean, some kids fucking eat sand/dirt for crying out loud. They aren't going to bat an eyelash to a big doggo they like.
Anyways, just don't think too much about it, lol.