You’ve decided to sell your horse and the potential buyer has sent a veterinarian to your farm to perform a purchase exam. As you stand beaming with satisfaction next to who you hope will be the new owner, the veterinarian picks up your horse’s left front leg. Bending it at the fetlock, he or she holds it for about 60 seconds, returns it to the ground, and asks that the horse be jogged down your asphalt drive. In astonishment, you watch as the horse moves off most decidedly lame. What happened?

What you have witnessed is a phenomenon not necessarily of the veterinarian’s creation but something that can sometimes occur following a procedure called a forelimb flexion test. In a forelimb flexion test, various joints and soft tissue structures of the lower limb are stretched and/or compressed for a brief period of time by bending the limb. Afterward, the horse is immediately trotted off and observed for signs of lameness.

Forelimb flexion tests were described in Swedish veterinary literature as early as 1923. They have become an integral part of the evaluation of the lame horse and are routinely included in prepurchase evaluations of the horse intended for sale. In performing the tests, a veterinarian will likely pick up the horse’s leg and bend it, with the bending force centering around the fetlock joint. He or she will hold the leg for a period of time, then let go, asking the horse to be trotted off immediately.

The test is not unlike what you might experience if someone asked you to sit in a crouch for sixty seconds, then run. Usually, you can run just fine, but occasionally, you might experience some soreness or pain in the joint that results in some initial stiffness. You might be normal or the soreness could signal a problem (such as a bad knee)