The Flexion Test

Is this nonspecific test the best way to identify problems during a veterinary prepurchase exam?
Author:
Publish date:


The purpose of the flexion test is to aid in identifying the approximate location and source of a lameness. But a flexion test merely points to a general area that is painful at that moment and is rather nonspecific. It is impossible to affect only one joint when doing a flexion test, and the test itself places stress on the joint capsule and associated ligaments and tendons. It also can place stress on cartilage and bone, causing pain related to existing arthritic changes in the joint. For these reasons, a positive flexion test will not produce an absolute identity or cause of lameness.

Credit: Dusty Perin/www.dustyperin.com Flexion tests can be problematic in that the results vary wildly depending on the person performing the exam.

Credit: Dusty Perin/www.dustyperin.com Flexion tests can be problematic in that the results vary wildly depending on the person performing the exam.

The approach and focus of a pre-purchase exam will vary depending on the age and current level of training as well as future expectations for the horse. Thus, it is imperative that the veterinarian doing the prepurchase exam have an understanding of the job the horse has done and the job that this horse is going to be expected to do by the buyer.

Because of the lack of specificity of flexion tests, a positive response warrants further investigation, which is not typically the realm of a prepurchase exam. It is up to the buyer to decide if he or she wants to spend money on radiographs and/or ultrasound. Performing anything invasive, such as nerve blocks, to try to isolate a source of lameness is up to the seller. A veterinarian who understands the job the horse is intended for can help the buyer make the most educated decision as to how far to proceed with the exam.

Flexion tests are problematic in that the results vary widely depending on the person performing the exam. There are no absolute rules for the degree of force or the duration of the flexion test. I have seen many horses made lame with overzealous flexions. This is particularly true with horses in their teens who have worked their whole life and are being purchased as more of a schoolmaster type. The question becomes a judgment call as to whether the horse can continue to work in a serviceably sound manner for the purpose intended. Veterinarians are put on the spot at this point because nothing is predictable and liability issues in pre-purchase exams have made many veterinarians extremely cautious about “passing” a horse.

One tactic that can be very helpful for the seller is to have a vet perform an exam—either a simple physical exam with flexion tests or a full work-up including radiographs—before a potential buyer even comes to see the horse, in part to help determine the intended asking price for the horse. If there is concern over a positive flexion test, a radiograph of the joint in question will help determine what the situation is within the joint. If everything looks good, the seller can let the buyer know about the exam, the result of the flexion tests and that radiographs are available.

If a horse shows discomfort from a flexion test one time and not the next, it could be that he was just a bit stiff one day and feeling better the second time around. It could also be related to the technique used by the person who did the flexion test or whether the horse had been turned out or worked and thus was warmed up before each of the flexions.
There are many things to consider when looking at a horse to buy. If he has a good history of soundness in the job the buyer intends to use him for, then there probably is nothing to worry about.

Tina Steward, DVM, MS, combines her knowledge of veterinary medicine, biomechanics, chiropractic, nutrition and FEI-level dressage to give a unique perspective as a dressage coach and veterinarian. She is based in Eugene, Oregon.

Related