Instructions
Pick up the front limb that you want to test. Most horses are trained so that they will lift up their leg for you if you slide your hand down the length of the leg and squeeze lightly on the backside of the cannon bone above the fetlock. Your helper should be holding the horse for you.
Apply pressure to the horse's leg by holding the leg up and bending the leg at the fetlock joint. Maintain pressure on the limb for between 30 and 60 seconds.
Set the leg back on the ground, and immediately ask your helper to have the horse trot away from you in a straight line.
Observe the horse trotting. If he appears to be lame (limping) in the leg that you just tested, then the flexion test is considered positive for that leg, indicating a possible problem.
How to Do a Flexion Test on a Lame Horse
A forelimb flexion test, which is sometimes also referred to as a flex test, is a simple procedure designed to test for lameness and potential problems in the lower part of a horse's front limbs. A flex test works by manually physically compressing and stretching the joints and tissues in a horse's front leg and then requiring the horse to immediately use the limb. If the horse is limping or off after the flex test is performed, it is a sign that there may be a problem in the horse's limbs or joints.