Dogs sticking together after mating or a copulatory tie occurs in canine reproduction whereas the penis is locked inside the vagina for up to 20 minutes, allowing the transfer of sperm with decreased leakage and therefore successful reproduction. Sperm is released at the beginning of the tie followed by prostatic fluid. Mating dogs should not be separated during the process.
The mating tie is a natural phenomenon. Dog breeders advise close supervision during the tie and separation of the dogs afterward. During the first breeding, a dog may try to pull away and run. Dogs should be calmed during this time until a natural tie separation occurs.