What you refer to as a knot is called a tie. Yes when they tie together is when the male inpregnants the female he lets off the sperm into the female.
The reason for the tie dogs do not ejaculate like a man does the sperm seeps through the penis at a time so this is the reason for the tie to ensure pregnacy.
The reason for the tie dogs do not ejaculate like a man does the sperm seeps through the penis at a time so this is the reason for the tie to ensure pregnacy.