You may notice, however, that your dog has a tendency to get along better with dogs of the opposite sex. (second-opinion-doc.com)
If you get dogs of the opposite sex, at least one should be spayed or neutered. (littledogtips.com)
If this is the case, look for a puppy or rescue dog of the opposite sex; males and females may not get along well with members of their own sex. (canismajor.com)