Improve you eye for lameness

Identifying the source of gait abnormalities can be tricky. Here’s how you can build your lameness-locating skills.


Does this scenario sound familiar?

A friend asks you to take a look at her horse: “He seems a little off, can you watch him jog?”

“Sure.”

You watch a few passes back and forth across the arena and, while it’s clear your friend’s mount is lame, you’re still unsure which limb is the problem.

“It looks like his left fore.”

“Oh. It felt like his hind leg.”

“Maybe? Could it be up in his shoulder?”

Don’t feel bad. Although determining that a horse is lame can be pretty straightforward, identifying the leg causing the problem can be anything but, even for those of us who do it professionally.

As a veterinarian specializing in sport-horse lameness, I spend all day analyzing equine gaits, and some diagnoses can still be extremely challenging. High-tech diagnostic tools, such as magnetic0 resonance imaging and digital0 radiography, can help us visualize the injuries and pathologies that make a horse lame, but we have to rely on our own eyes and experiences to determine where to look.

Horse owners and caretakers, who are the first responders in lameness cases, can play an important role. You see your horse regularly and know what his “normal” looks like. You also know when something’s not quite right with your horse’s gait, even if it’s hard to articulate exactly what you are feeling or seeing.

When you decide to call your veterinarian about a potential lameness issue, the information you pass along may determine the initial approach to the problem. And even after treatment is initiated, you will be the “eyes on the ground” watching for improvements or setbacks. In short, the better you become at detecting lameness, the more helpful you can be in your veterinarian’s search to identify and treat it.

With that in mind, I’d like to share just a few of the many things that veterinarians watch for during a lameness examination. These are things we learn through our formal education as well as field experience, but you can learn as well. As you read, keep in mind that all the tips and tricks in the world are no substitute for experience. So get in the habit of watching horses closely---others as well as yours---and studying how they move.

FUNDAMENTAL TERMS AND TECHNIQUES

Let’s start with the basics. What is lameness? Any gait abnormality that is new and might be due to pain is considered a lameness. In contrast, a horse who isn’t in pain but has a mechanical anomaly/abnormality that makes him walk funny isn’t lame,per se, though it is still advisable to investigate the cause (see “LameWithout Pain,” page 37).
It’s also important to understand how lameness is quantified. Many Europeans use a 10-point scale and some veterinarians develop their own variations. But for the most part in this country we describe lameness using a 0-to-5 grading system developed by the American Association of Equine Practitioners. Having a standardized grading system for lameness helps facilitate communication between veterinarians about a horse’s situation and progress, but owners can also benefit from knowing the scale and how to apply it. Here’s how it breaks down:

0: Lameness not perceptible under any circumstances.
1: Lameness is difficult to observe and is not consistently apparent, regardless of circumstances (including under saddle, circling, inclines and traveling over hard surfaces).
2: Lameness is difficult to observe at a walk or when trotting in a straight line but consistently apparent under certain circumstances (including weight carrying, circling, inclines and traveling over hard surfaces.).
3: Lameness is consistently observable at a trot under all circumstances.
4: Lameness is obvious at a walk.
5: Lameness produces minimal weight bearing in motion and/or at rest or a complete inability to move.

Grade 1 lamenesses can be very challenging to see, and we may rely on other conditions to make the diagnosis. The horse may not look lame, but there will be important clues in his history. The horse feels off or isn’t smooth when he’s ridden. Maybe he suddenly won’t pick up a lead or he begins refusing fences. Or maybe he is a bit reluctant to perform or has abrupt transitions. These complaints seem vague, but they are valid and useful observations when it comes to investigating lameness. If a horse doesn’t “feel right” to his regular rider, he probably isn’t.

A BASIC EVALUATION

When observing a horse for potential lameness, don’t just chase him in the round pen for a few strides. You’ll get no useful information that way. Instead, take a few minutes to set the stage for a more “formal” lameness assessment.
Start by observing the horse when he’s not moving, from all angles. Look for asymmetries---his left side should look just like the right. Some minor asymmetries are normal, but really pronounced differences in muscle mass, limb conformation or joint size can be indicative of lameness. You’ll need to consider this information in a larger context, though, so make a note of it and move on to jogging the horse.
Obviously, if a horse is not moving well at the walk, there’s no need to make him trot to confirm that a call to the veterinarian is in order. However, lameness is often much more subtle than that, and we generally look for it at the trot because it is a symmetrical, simple gait. It is a two-beat stride with equal weight bearing on each diagonal in sound horses. A horse can “hide” lameness at the walk because there is minimal concussion, and the canter is a fast, asymmetric gait. Thus, if a horse is lame, we are usually going to see it in the trot.
Here, I’d like to say a quick word about gaited horses: Looking for lameness in Tennessee Walking Horses, Paso Finos or other gaited horses may be challenging because they do not have a two-beat trot. The discussion in this article may not necessarily apply to those horses because we focus on the two-beat trot for lameness detection. Many of the principles of lameness detection may be employed with these horses but gait irregularities can be harder to detect and require a more experienced eye.
Ideally, you’ll have someone to trot the horse for you. Have her lead him on a loose line---it is important that the horse’s head is not restrained. Start at the walk, then have the helper cluck and begin jogging to encourage the horse to pick up a trot to follow---again, no pulling on the lead. If the horse is reluctant to trot, a tap on the shoulder with a long dressage whip can provide some encouragement, but be careful to avoid getting stepped on.
Jog the horse on a flat, firm surface where, ideally, you have enough room for a long, straight stretch of 15 or more strides. Start by watching the horse trot toward you in a straight line, paying particular attention to his head movement. Then observe the horse trotting from behind, focusing on his hips. Finally, stand to the side and watch the horse trot past you, standing far enough away so you can view his entire body. If you need to gather more information, longe the horse---some lamenesses reveal themselves better on a circle---or try different footing. Sometimes it helps to see the horse being ridden but the addition of a rider can also complicate the lameness. 

SPOTTING FRONT-LIMB LAMENESS

The indicator of lameness that is easiest to see is the head bob. In sound horses, the head will move up and down slightly twice during each trot stride. It is up during the swing phase and down during the stance phase of each front limb. In a sound horse the motion of the head and neck will be symmetric for both sides.
A “head bob” is often seen when this motion is asymmetric between the two front limbs and exaggerated downward on the sound leg. This is typically associated with front-limb lameness. Most people with moderate horse experience can detect a bob, but that only tells you that a something is wrong. You have to understand why and how the bob is happening to utilize it as an indictor of which limb is the problem.
Essentially, when a horse is bobbing his head, he lifts it just before the painful leg lands. He uses the considerable weight of his head and neck to shift his weight and to keep it off the sore limb as much as he can. The down motion on the sound leg is exaggerated because this limb is accepting greater weight bearing. We use the phrase “down on sound” to remember this relationship, but sometimes the “up” is the only thing you’ll see.
A sound horse jogging on a longe line will land comfortably on the inside limb, both front and hind. The inside limbs tend to bear more weight so when the sore limb is on the inside of the circle the lameness may be exacerbated. For example, a lameness in the left front limb will typically become more pronounced when the horse is circling to the left. So be on watch for a horse transferring weight to his outside limb as he’s being longed. There are exceptions to this rule (see “Hooves on the Ground,” at right).

SIGNS OF HIND-LIMB LAMENESS

Identifying hind-limb lameness is a little trickier. Watch the horse jog away from you, focusing on the topline of his rump. With each stride, there will be motion in that line. Look at the total motion on each side---it should appear to be equal. If one side has more total motion than the other, we tend to suspect lameness in that limb. Some people refer to “hip hike,” but it’s not a matter of height, it’s more the total amount of movement.
One thing that can help in the detection of hind-limb lameness is athletic tape. When working with students, I put two six-inch strips of tape on the horse’s rump, about four inches off of the midline over his croup. These “racing stripes” give the eye something to focus on as the horse trots away.
In the hind limbs, the telltale motion isn’t related to weight bearing. During the “swing phase” of the lame leg, the sound leg is bearing more weight and therefore the horse is dropping lower on the sound side. In response, the lame leg has to swing even lower, causing that hip to appear to drop. Then during the stance phase of the lame leg, the horse is reluctant to bear full weight, resulting in an elevation of that hip (you may see this as a “hip hike” but not always). You may also notice that the lame leg will move more quickly during this swing phase to play catch-up.
When looking at the horse from the side you’ll see the painful hind leg come off the ground more quickly than the sound limb. There will also be less “fetlock drop” (fetlock extension) in the lame limb because it is bearing less weight. If the horse is moving in a circle---on a longe line, for example---you can watch for fetlock drop, stride length and asymmetry in weight bearing. Keep in mind, however, that the inside leg has a shorter stance phase to begin with. 

PINPOINTING THE PROBLEM

If you’re confident you’ve identified the potentially sore limb, start checking for obvious injuries or areas of heat or swelling. You may not find anything. A hoof abscess, for instance, won’t reveal itself beyond the lameness. But a puffy, sensitive tendon on a lame leg is a good bet for what’s bothering the horse and information you’ll want to pass along to your veterinarian.
I hear from a lot of owners that a lameness is coming from the horse’s shoulder. It usually isn’t. In fact, shoulder injuries are very rare, and 80 to 95 percent of lameness is caused by problems from the fetlock down. The lame leg will often have a shortened stride and it will look like the horse doesn’t want to pull the limb forward, therefore, it is assumed to be a shoulder injury. So don’t be surprised that even if you assure your veterinarian that the pain is in your horse’s shoulder, he will still start by looking at the foot.
If you’ve determined it’s a hind limb that hurts, and you don’t see any obvious signs of trouble, it’s a bit of a guessing game as to which joint has the problem. People are quick to pinpoint the hocks, but you definitely need to block those to make that determination. It’s a complex limb and your eyes just aren’t reliable enough to know where the lameness is coming from just by watching the horse move. Whenever possible, we try to block out the lameness just as we would in the front limb.
As you get higher up in the hindquarters, lameness is a diagnosis of exclusion: If blocks and imaging show nothing from the stifle down, the problem could be in the horse’s hip, sacroiliac joint or even back. Typically hind-limb lameness causes back pain because the horse moves differently. But in a few cases the relationship can be reversed and back pain can be the source of the lameness.

It would be great if there were a simple and surefire method for determining which leg is making a horse lame, but identifying the source of the problem is as much art as science. Advanced technology allows us to apply more objective measures to lameness assessments, but the human eye is still an important part of every examination. That means there will always be trial and error. But by taking a step-by-step approach, you can develop your eye and improve your ability to interpret what a limping horse is trying to tell you.

This article first appeared in EQUUS issue #460, January 2016.