@Gina338 And as far as the bag goes, contact Airbnb, tell them you accidentally left a bag behind and that the owner is refusing to answer your messages. Deal with that as a separate issue, don't mention the vet bill. Wait to see if they submit a request for the vet bill through Airbnb platform, if not, you can forget about that part, or deal with it if and when they do. They can't keep your bag just because they want you to pay a vet bill. And if you want the bag back, I assume you've offered to pay for shipping, as that part isn't the host's fault.
BTW, I think their behavior was bad- acting likie everythings okay re the dogs, then springing that on you.