Castrating a male dog has nothing to do with population. Male dogs are not the ones who actually have babies. Female dogs should be spayed to prevent overpopulation. If a female dog isnt spayed the chances for mammary cancer are high. Neutering a male dog increases their risk of prostate cancer. Almost all dogs who have prostate cancer are neutered and not intact. Please view the enclosed as evidence. link.
Castration of Male Dogs