Understanding the Role of Flexion Tests in a Pre-Purchase Exam

Photo by Jump Media

By Sabrina Brashares/Jump Media

If you are a horse owner, you are probably familiar with flexion tests. Most pre-purchase and lameness exams involve a vet performing flexion tests on the horse. This type of test involves a veterinarian applying stress or pressure to various joints for a brief period of time and then immediately trotting the horse away. While the horse is trotting, the vet observes the effects of the flexion test on the horse’s gait and movement. This type of evaluation can reveal discomfort or weakness that may not be present during a normal jog.

Although flexion tests are very common, there are certain drawbacks and considerations that should be taken into account. We spoke with Dr. Scott Swerdlin, President of Palm Beach Equine Clinic, to learn more about flexion tests and factors that should be considered when performing them, especially for a pre-purchase exam.

Dr. Scott Swerdlin. Photo by Jump Media

At what point in a pre-purchase exam do you utilize flexion tests?

A pre-purchase exam starts before you begin the flexion tests, and what you learn about the horse at the beginning of the appointment should be taken into account once you start flexing them. The first thing I do is look at the horse in the stall. I observe the horse to see if they have any habits such as being a stall weaver or cribber. All of those small details are very important. Next, I want to watch the horse come out of the stall and observe how they are walking. It is important to watch the horse walk in a straight line. While watching, I try to get down close to the ground so I can see the horse’s conformation. I ask the horse to bend a couple of times to the right and a couple of times to the left. I will then put my hands on the horse and check them all over. I check the jugular on both sides to make sure there are no problems there and then run my hands down all four legs. After a period of time, you get pretty good at being able to perform a thorough exam with just your hands. They do not teach that as much in veterinary school now, but I try to teach that at Palm Beach Equine. After that, I pick the leg up and palpate all the soft tissue structures individually on all four legs. Once those tasks are completed, I am ready for the flexion tests. Before the flexion tests even start, I already have a pretty good idea of the horse. The flexion tests are just one small piece of the puzzle.

How are flexion tests used in a lameness exam?

When you are doing a lameness exam, flexions can be very helpful because they give you a general area to concentrate on. For example, if the horse is lame in the left fore, you would start your flexions with the coffin joint, then the fetlock joint, then the carpus, then the shoulder, and then go to the back leg. When you are doing flexion tests in a lameness exam you are watching for an increased response or sensitivity to help pinpoint a certain problem area. Then you start doing local anesthetic blocks to make sure that that’s not where the horse is lame.

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Would you say flexion tests are more useful in a lameness exam than they are in a pre-purchase exam?

Yes. I think some veterinarians pay too much attention to flexion tests in a pre-purchase exam. It can interfere with a sale where the horse and rider are a good fit for each other. I would even say that it’s not so fair to the horse, owner, or prospective buyer to place too much emphasis on flexion tests.

What factors do flexion tests not take into account?

There are a lot of horses that flex positive in a pre-purchase exam but are still a great match for the client. You have to take into account a couple of different factors when doing flexion tests. I try to take into consideration the type of work the horse has been asked to do, the level of work the horse does, how long the horse has been fit, the age, breed, and conformation of the horse, and the job the horse will be doing for the prospective buyer.

For example, there are some horses that are built long in their pastern and based narrow. When you flex them, and you put enough pressure on the back of their suspensory and sesamoid in the back, they will be uncomfortable on the flexion test. That does not mean there is anything wrong with the horse, it is just a result of their conformation. Another example is when a horse who has been playing polo all season has a positive flexion test. I would not find that surprising because I understand the amount and type of work the horse has been doing with little time off.

Flexion tests also do not tell you why the horse was positive. We do not know if they are positive because of the anatomy, because the horse has been in a lot of work, or because the horse just needs a little bit of time off. In a pre-purchase exam, flexion tests also do not determine the future soundness of a horse or tell you whether or not to buy the horse.

How does a horse’s age affect what a flexion test can and cannot tell us?

I think that there is more meaning when a horse that is five to 12 years old has a positive flexion than when you get a positive flexion on a horse that is 12 to 16 years old.

On a pre-purchase exam, we usually want to try to find out if the horse is a good fit for the use intended. If I have a positive flexion and the horse is 14 years old, I might be comfortable with that. Similarly, I would be fine with a positive hock flexion on a 12-year-old warmblood that has been showing, and I almost would expect that. In fact, sometimes when you are flexing an older horse and they are perfect then you start thinking, “This horse has been injected here, so where else has it been injected?”

Another example is a horse that is 12 years old and has been jumping grand prix classes that comes up positive in a hock flexion. That result does not necessarily mean anything. However, if you have a horse that is four years old with the same positive flexion, then that could be significant. In the end, the buyer makes the ultimate decision—we are not saying yes or no, we are only providing a recommendation, which is dependent upon the use intended.

Can it be harmful to perform a flexion test on a horse under the age of 3?

Absolutely not, but I also have never heard of a veterinarian performing flexion tests at such a young age.

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Can flexion tests be done incorrectly?

I do sometimes see younger veterinarians flex a joint to the extent that pretty much any horse would trot off a little unsound. Although I’ve never seen it harm a horse, I have seen veterinarians have the horse trot off positive when in fact there wasn’t any pathology there. It depends on the veterinarian’s experience level, procedure, and where they put the emphasis. Can veterinarians make a horse trot off lame after a flexion test? Yes.

Do you think certain points are more important to flex than others?

Yes, I think depending on the use intended of the horse there are certain areas that are more important than others. For example, I think hock flexions in a polo pony are not too important, but they are very important in a dressage horse. For polo ponies, fetlock flexions are really important. Doing medial to lateral flexions where you do an abduction of the hip and the back legs is very helpful for jumpers.

One of the flexion tests I think is very helpful and veterinarians don’t do enough of is the carrot test. This is where you see if a horse can pick up a carrot from in between their legs, then hold the carrot to their sides and ask them to bend to the left and right. I would consider this a flexion test because you are flexing the cervical vertebrae. If you see dissymmetry that could mean something, especially for dressage horses.

While flexion tests can be useful during a pre-purchase exam, the veterinarians must first understand the horse’s background. When assessing the results and importance of the flexion tests, factors such as the horse’s workload, age, conformation, and job for the prospective buyer should be taken into account. Flexion tests alone should not be the deciding factor in a pre-purchase exam.

For more information about Palm Beach Equine Clinic’s facility, services, and team of veterinarians, visit equineclinic.com.

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