Visit a responsible and reputable breeder. It is really important to only use reputable breeders as your puppy's genes will determine their health and disposition as an adult. Signs that the breeder is a responsible and reputable breeder include a desire to better the the breed.
In fact, many responsible breeders will keep the best puppy out of the litter and require that people who adopt boxers with faults sign agreements to spray or neuter their puppy. Responsible breeders are also in full compliance with the laws in their area on breeding puppies.
Boxer - Dog Lover
