Two dog’s butts sticking together

Two dogs’ butts sticking together means dogs are mating. This is called a knot. When dogs mate, the male dog's physiological structure causes the male dog to lock the female dog's reproductive tract, which is more conducive to the success rate of mating. Therefore, there will be a phenomenon of two dogs' butts sticking together. This phenomenon indicates that the mating is about to end. There is no need to force them apart, just wait until the mating is over.