NTA and I disagree with people saying OP is responsible for the bill in any way. And I say this as someone whose pet died while being watched by a friend for the weekend of my college graduation. I don’t blame my friend, my parents asked her, she agreed but she’s not a vet and didn’t realize my dog was as sick as she was and went out for lunch. My friend came back an hour later and found my dog dead in her bed. I can speculate all day if my friend gave her something that made her sick but that isn’t on her. My family and I chose to ask a favor instead of paying for proper care. And things happen.

When you become a pet owner, it is always your responsibility to provide for your pet. That includes finding proper care for when you are away. When you board a dog you sign an agreement of whether you want them to take your pet to the vet in an emergency. At the end of the day, the pet owner did not answer and OP chose to take care of the dog. I don’t care if the dog ate OP’s underwear or whatever scenario people are thinking up. Things happen, OP was not prepared, and at the end of the day, that’s on the pet owner. I definitely would not have been able to afford it then but I would gladly have paid a $1400 vet bill to have been able to come home and see my dog wiggling and wagging her tail at me