When dogs mate, the male mounts the female, making thrusting movements, and eventually his penis enters her vulva and starts to swell, especially the bulbourethral gland at the base. As the bitch's vulva contracts around his swollen penis, the dogs become stuck or "tied" together.
During the tie, the male turns around so the dogs are back to back and can defend themselves. The tie typically lasts 20 to 40 minutes. It may be just a few minutes, and dogs can mate successfully without becoming tied at all. The evolutionary reason for the tie is unknown, but it's assumed that if a male dog is tied to a female, it prevents other males mating with her.
Never try to pull the two dogs apart, even when mating is unwanted. This can damage the dog's penis and the bitch's vulva. Seek the help of a veterinarian straightaway after an unplanned mating to avoid having pups. By neutering male and female dogs you can prevent mating and unwanted pregnancies.
- Caring for Your Dog; Dr. Bruce Fogle
- Veterinary Notes for Dog Owners; Trevor Turner, B.Vet. Med., M.R.C.V.S.
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