Points of the dog (Are its knees backwards?)
It's a terminology thing. The correct terms for quadruped rear limbs are "stifle" for the equivalent of the human knee, and "hock" for the equivalent of the ankle, then fetlock (heel) for the next one down. For the front limbs, the elbow is up near the chest and the knee is the equivalent of the human wrist. The horsy world still seems to use the proper words, as I suppose do veterinarians.