When dogs were young, both men and women squatted to pee. But in adolescence, about eight or nine months, the male dog will start to lift one hind leg when he shoots urine. The raised legs are stiff and straight, and the body shape is at an angle, so that the urine is directed to the side instead of going down to the ground under the feet.
Male dogs have a strong desire to lift their legs and pee. After a long walk with an obvious smell, the urine may have been used up and can no longer be urinated, but in this case, you may observe the male dog trying to squeeze out a few drops of urine just to leave his "business card". Even if the bladder is completely empty, they will continue to lift their legs, which has nothing to do with the need to excrete liquid waste.
Strangely, leg lifting has nothing to do with male reproductive ability. If male dogs are ligated before puberty, they will still have leg lifts at the same age as male dogs with completely normal sexual ability. It can be seen that although leg lifting is the action of mature male dogs, it seems to have nothing to do with the secretion of testosterone (some people may think it has something to do with it).
However, although this action is not caused by sex hormones, it does leave sexual physiological information of dogs, because sex hormones will be excreted with urine. There are also special and independent secretions from male accessory glands in urine, which makes each odor tag have an independent identity tag.