its simple, take them back to the breeder.....a responsible breeder will always take back anything they ahve bred nomatter what the circumstances, and in most cases there will be a contract saying that they MUST go back if such a situaton arises as this. A responsible caring breeder is responsible for anything they breed if it needs to be rehomed. Simple moral ethics of breeding.
Aye sell somebody a pup that is perfectly healthy and once the new owner has had it for 13 months and turned it into a problem,you have the responsibility to take it back
and sort it out,somehow I don,t think so,