A "wind puff" refers to the accumulation of synovial fluid with the distal flexor tendon sheath of the lower leg. All 4 limbs have a distal flexor tendon sheath and they extend from just above the fetlock down to the coffin bone area. Most people notice the swelling once it is above the fetlock joint however there is often significant fluid within the pastern area that goes unnoticed. For many horses that are in regular work a mild amount of fluid accumulation within the flexor tendon sheath is normal and should be symmetrical. When there is more fluid in one leg or a sudden increase in fluid then there is reason to be concerned.