During this phase, both the male and female dog are actively involved. The male's penis swells and locks into place due to a muscular contraction, preventing him from withdrawing. This lock is crucial to ensure that the sperm has time to travel to the female's reproductive tract and increase the chances of fertilization.
So, rather than assigning responsibility, it's more accurate to say that both the male and female dog are involved in the tie-up process, each playing a crucial role in this natural part of canine reproduction.
If you have further questions about canine mating, it's best to consult a veterinarian or a reputable animal behaviorist for accurate and informed information.