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What is a Forelimb Flexion Test – Horse Flex Test ?

A flexion test is a preliminary veterinary procedure performed on a horse, generally during a prepurchase or a lameness exam. The purpose is to accentuate any pain that may be associated with a joint or soft-tissue structure, allowing the practitioner to localize a lameness to a specific area, or to alert a practitioner to the presence of sub-clinical disease that may be present during a pre-purchase exam.

Forelimb Flexion Test

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).

While forelimb flexion tests are quite commonly performed, veterinarians have not agreed on the optimum duration of the test, which according to reports can vary from 30 seconds to three minutes. Although there are devices available to measure the force applied during the test, these are not widely used in practice. A study involving 50 horses has been conducted to determine the effects that force of the test might have on the result. The study suggests that reliance on forelimb flexion tests for a diagnosis of impending lameness or other problems is not reasonable. The study also indicates that a positive response to the test does not correlate well with other indicators, such as X rays of the lower limb.

A positive response to forelimb flexion tests, meaning lameness was evident after the limb was released, is one reason horses might be deemed unsuitable for purchase during the prepurchase exam. There seems to be a wide range of significance attributed to these tests that varies according to opinion and the experience of the examiner. There appears to have been many purchase exams discontinued solely because of a positive response to a flexion test in one or both forelimbs. Because of the variable response to the test depending on such things as the force applied, duration of the test, age of the horse, and the day of examination (demonstrated in this and other studies), discontinuation of a prepurchase examination based solely on a failed forelimb flexion test probably is unwarranted.

Owners and trainers seem to have become increasingly skeptical of the significance of the forelimb flexion test during these examinations. Horses can and do perform well for a variety of riding endeavors even when they do not perform well on a forelimb flexion test.

If your horse does limp after a forelimb flexion test, don’t stop there. Further examination of the horse through the use of such techniques as X ray might be warranted. Look for other supporting signs, such as lameness, loss of limb flexibility, or a painful response to palpation and/or manipulation of the area that you suspect could be a problem. With a complete examination, you will likely receive the answer you are looking for.