I doubt the new owners are going to be successful; however, if you have home owners' insurance or renter's insurance, notify your insurance company and they should handle everything for you.
I agree that they probably don't have a case. Did you find out what happened to the dog?
This is not to be construed as legal advice. I do not have an attorney client relationship with you.
Sign up to receive a 3-part series of useful information and advice about personal injury law.