Bulbus Glandis on the Penis Swells

A tie occurs when the bulbus glandis on the penis swells and the vagiva contracts around it, preventing the dog from withdrawing his penis from the bitch's vagina.

They are stuck, or "tied," together. The tie typically lasts for 20-40 minutes. A prolonged tie may be painful to the bitch; she may turn and snap at the male when it ends.

A tie lasting a few minutes, however, seldom causes discomfort and is usually successful. After mating, both the male and female vigorously groom their genital regions by licking, an action that cleans away debris from the area and kills some harmful bacteria.