Tying a mud knot—sometimes called a war knot or mustache knot—in a horse’s tail is a vaquero tradition still practiced in buckaroo country. It keeps long tails from getting tangled up in ropes, and out of the mud and brush.
Separate the horse’s tail into two equal sections. Traditionally, the knot is tied before the horse is tacked up, and should be untied before the horse is returned to the cavvy.
Tie an overhand knot—bring the left strand over the right strand; bring the right strand over the left strand and through; then pull tight.
Take the strand on the left and bring it up and around the horse’s tail—front to back—counterclockwise. Hold the strand in place. Make note of where the strand crosses in front of the tail; this will be important in Step 4.
Take the strand on the right, and—going clockwise—bring it around the back of the tail then forward and through the loop created by the left strand in Step 3.
Pull both strands down and out to tighten the knot. To secure, pour water (though some cowboys prefer to use coffee) over the knot and tighten again.