The birth of a litter of puppies brings with it a host of responsibilities for the owner. Besides ensuring that the bitch is provided with the environment and veterinary support needed to give birth and care for her pups, the owner must also be aware of how the father of the litter -- the sire dog -- will react to the arrival of the puppies.
While your bitch is pregnant, the sire will become excited around her, as the hormonal changes in her body will generate smalls that entice the sire. His interest can stress the bitch and so the sire should be kept away from the bitch during the last few weeks of pregnancy. This also prevents the bitch's belly being bumped during play, which can cause stillborn pups.
The owner should provide the bitch with an enclosure or box in which the bitch can give birth. This is called a whelping box and should be a private area and the sire should be kept away from it. The bitch will likely become agitated and aggressive if any other dog, including the sire, is around the birthing enclosure. This is because sires do not have a natural paternal instinct, and the bitch recognises the potential threat of a male dog to her newborns.
The sire should be kept away from the pups for a few weeks after they are born. Until they are five or six weeks old, the pups have their eyes closed and are essentially helpless. The sire does not have a paternal instinct and, while rare in domesticated dogs, male dogs can kill newborn pups to bring the bitch back into sexual receptivity.
A sire dog should be introduced to the puppies as you would introduce any dog, related to the pups of otherwise. You may be able to allow the sire to see and sniff the dogs while still in the birthing enclosure, after around two weeks. The bitch will let you know if this is acceptable. If not, hold a puppy in your arms and keep the sire on a lead. Allow the sire to sniff the puppy. This is how dogs recognise one another, and the more the sire sniffs the puppies, the less "alien" the small and the more accepting the sire becomes of its presence.
Once the sire has been introduced to the puppies and has accepted them as a part of the pack, he will play an important role in the socialisation of the puppies and their learning the codes of behaviour within a hierarchical pack. The sire - - like the bitch - - will admonish the pup if it breaks the "rules" (for instance, plays too aggressively). Such teaching of hierarchy can help socialise the pup for human interaction as well, as the owner becomes the de facto head of the "pack."