How does the dog mating process work?

During mating, the male dog inserts his penis into the female’s vagina. The male’s penis contains a baculum (penis bone), so it can enter without full erection; once stimulated by the female’s vagina, the bulbus glandis at the tip swells with blood and enlarges, locking the pair together and completing the mating. Because dogs are hard to separate during mating, it is best not to disturb them to avoid accidents. After a successful mating, they will separate naturally.