When a female dog becomes a new mother, she typically wants to spend time alone with her puppies. She may not appreciate interference from other household pets, particularly male dogs, who may become aggressive or rough with the vulnerable puppies. However, if the male dog happens to be the puppies’ father, he might provide some welcome assistance for his new family.
According to Bonnie Beaver in "Canine Behavior: Insights and Answers," wild dog fathers often play important roles in their puppies' lives. They provide protection for the new family, help with feeding by regurgitating food, and may give the mother some much needed rest from her rowdy brood. Although domesticated dads are not always as involved, they may provide protection for the puppies. Of course, the mother dog will usually let the father know if he is unwanted or if she is unhappy with his treatment of her puppies.
Other Male Dogs
The mother and her puppies should be separated from other household pets initially so the new family can rest. Eventually, other male dogs can be introduced as long as the interactions are supervised by both the owners and the puppies’ mother. Jerrie Wolfe, who breeds Cairn terriers and advises other breeders, believes male dogs help puppies understand the social order of the pack while reducing puppies' fears of male dogs. Of course, male dogs who show any sign of aggression or who make the mother uncomfortable should be removed from the puppies’ proximity immediately.