It sounds to me like you are claiming a 'breach of contract' in that the dogs cannot be used for breeding, and possibly a violation of the 'warranty of merchantability' in that the product cannot be used for the purpose that it was clearly intended.
So first, you need to determine if you have a contract and if there was an understanding of the use of the 'product' (I know, these are dogs, not equipment, but in the eyes of the law, they are property and not live animals).
1) Does the bill of sale (contract) refer to these as 'breeding' dogs? If so, then you might be able to support your claim.
2) What, if anything, does the bill of sale say about if the dogs were not acceptable for breeding??
3) What is the (fair market) value of the two dogs if NOT for breeding purposes?? (I don't propose to know the value, but it seems that $1500 for two mastiffs does not represent an excessive value... and based on answers to these questions that difference in value may be your only 'damages'.)
4) Do you have the sellers agreement ("would work with us on it") in writing?? If not, send them a letter (Certified RRR) detailing your situation, there statement to work with you, your out of pocket costs and what you expect them to do. Let them know that you are willing to negotiate a resolution. Give them a specific deadline (7 days??) to respond. Make your letter neutral and to the point. Do not ramble or threaten.
5) Finally, is this raised 'testes' a problem that either cannot be 'fixed' or something that an experienced 'dog person' should have noticed on inspection??? If yes to either of these, it could weaken your case.
Finally, you need to decide what you will do. I have known of several of these cases where the 'new' owner has fallen in love with the dogs anyway and still wanted to keep them. If this is the case, then you could not recover any costs (food, boarding, etc) since they would be normal expenses. Are you prepared to give both dogs back if you pursue this matter to the end (either court or agreed return)???
