Mating habits in dogs (male)
Once males have reached sexual maturity which can occur from about six months onwards, the male dogs are able to breed at any time throughout the year. The sexual maturity period also varies from dog to dog. The testicles which produce sperms normally descend from the body cavity into the scrotum at birth. In some cases, however, one or both testicles are retained within the body. This state is known as cryptorchid. The hot and moist temperature within the body does not let the retained testicle function normally. If only one testicle descends, the dog is still fertile. If both testicles do not descend and are retained within the body cavity, the dog remains sterile.