Dogs need to mate when the female dog is in heat. When dogs mate, the male dog will ride on the female dog and then mate through fertilization through the reproductive organs. The mating process lasts about half an hour. When dogs are mating, it is best not to disturb them to avoid scaring or irritating the dogs. Also, you cannot force the dogs to separate during mating, as this can easily cause damage to the reproductive organs. It is best to wait until the dogs have finished mating and separate on their own.