I'm sorry you are going through this.
The problem here is you bought the dog through a third party.
If I read your post right.
Contracts usually do not cover or carry over to another person.
Unless the breeder approves it.
The first person who purchased the dog never had the dog spayed which voids most contracts.
Are you sure the person you bought the dog from, didn't know the dog had a shunt and passed the problem on to you?
If you had purchased directly from the breeder, then she would of had to cover the dog...
I'm sorry but I don't think there is anything you can do about it.
Has this breeders.. breeding dogs been tested for shunts?
Was the dog you purchased inbred?
There are a couple different types of shunts.
http://www.peteducation.com/article....&articleid=882 http://www.vet.utk.edu/clinical/sacs/shunt/faq.shtml http://www.petsdoc.com/html/asktheve...vershunts.html