It is true that Tibetan Spaniels look like little lions. If a dog lives alone, he will not normally have any puppies. If dogs live in a group, they will likely breed. We let nature take care of itself. It can happen that a Do Khyi bitch is brought to a very good Do Khyi sire. The appearance should not be over-estimated.
Let me tell you a short story, which describes the relationship of the Tibetans to their dogs. I am friends with a Tibetan family who lived in Switzerland. They had a St. Bernard. This dog resembles in many ways the ideal Do Khyi: very big body, big head and impressive bark. When the parents retired, they went back to Tibet. The children stayed in Switzerland. However, the parents took the dog back to Tibet with them, where he received a lot of attention and admiration. When people noticed he was a very gentle dog, they were surprised and said: Why do you keep a dog that neither barks nor defends its owner but still eats a lot?