I understand you feel betrayed by the whole thing, but when you give someone an animal it becomes their property to do with as they please within the confines of the law. If you didn't have a contract giving you first option of refusal in the event they want/need to get rid of him there's nothing you can say or do about it.

That's why dog breeders will often have a first right of refusal built into the contract. So no one can do what has been done here without repercussion.