The Lameness Scale, Demystified

If you’ve ever owned a horse or ridden consistently you will at one point in your riding career have to manage an unsound horse, be it “head-bobbing” lame or lameness barely visible to the untrained eye. The degree of lameness, however, will depend upon the injury and/or cause.

As a horse owner dealing with a branch suspensory injury for the first time, I have to admit that I’ve never been great at “seeing” lameness unless it’s of the head-bobbing variety – and each time in my case that was due to a hoof abscess. I can, however, assess soundness when I’m riding. I can “feel” shortening of strides, inability to track up, stiffness. But to my untrained eye degrees of soundness are a different story.

You may be an experienced horse owner and can evaluate the degree of unsoundness yourself, but most of us rely on our veterinarian to tell us how “off” our horses are. To do this, the majority of vets perform a lameness exam and flexion tests that use the lameness scale from the American Association of Equine Practitioners (AAEP).

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To take this common 5-point lameness scale point by point, and help us navigate it, we turned to Dr. Kate Robinson, a vet with McKee Pownall in Ontario.

0: Lameness not perceptible under any circumstances. This one is self-explanatory and where we want all four limbs and feet to be.

1: Lameness is difficult to observe and is not consistently apparent, regardless of circumstances (e.g. under saddle, circling, inclines, hard surface, etc.). “One is a mild lameness that’s really only seen at the trot and is never consistent, regardless of the circumstances,” she explains. “It’s really mild and it’s one of those that’s tough for us to even be pinpointing.”

2: Lameness is difficult to observe at a walk or when trotting in a straight line but consistently apparent under certain circumstances (e.g. weight-carrying, circling, inclines, hard surface, etc.).
“A two out of five then is only lame at the trot,” Dr. Robinson explains. “Not lame in every circumstance, but we can make it consistent in certain circumstances.” She used examples that the horse is off on hard ground but not on soft ground or they’re off on a circle but not on a straight line.

3: Lameness is consistently observable at a trot under all circumstances. “A three is what we call a “student lameness,” so named because a student at veterinary college should be expected to detect it right away,” Dr. Robinson says. “The horse is lame at the trot in all circumstances, so whether that’s in hand on the straight hard ground or even on soft ground at the circle, regardless of direction.” She adds it may not be an obvious lameness, but in all of those circumstances, the observer is able to see a bit of a head nod or a hesitation on the leg that’s telling them that the horse is off, in all circumstances.

4: Lameness is obvious at a walk. This one is also self-explanatory and also what I was told my horse registered on the injured leg after a flexion test. Even I was able to see the uneven strides.

5: Lameness produces minimal weight-bearing in motion and/or at rest, or a complete inability to move. The worst-case scenario for any horse and horse owner!

As horse owners should we be assessing our horses daily using the lameness scale? “We don’t want to drive ourselves crazy over-analyzing everything,” Dr. Robison warns. “But I think it’s developing an eye for what is normal for your horse.”

She explains that owners have to understand that in different situations a horse will move a little bit differently on a gravel driveway where maybe they’re trying to avoid stones versus soft arena footing. It’s the same when you’re riding or watching your horse going up and down hills – they’re going to move a little differently, but that doesn’t mean there’s a soundness issue.

It’s a good idea to learn what your horse’s “normal” is. Watch and learn to recognize when the horse is “tracking up” at the walk from hind leg to front. This is easiest to see when your horse is walking on soft ground where you can see the hoofprint of the front foot; the back foot should fall in front of the front hoofprint evenly on both legs. For the front limbs, you’re looking at the stride length and if is it even right to left. You can also assess if the horse has equal reach with their legs by putting them on the lunge line and watching them from the inside of the circle.

When the vet performed the lameness exam on my 16-year-old Dutch Warmblood, she did flexion tests as well as watching him trot and lunge. This is where the vet holds the leg in a single position for an amount of time that varies from 30-90 seconds seconds before releasing the joint and watching how the horse moves after. The length of the “hold” depends on what flexion is being performed, and there is variation from clinician to clinician as well.

The point of a flexion test is to specifically stress one region of the leg and see if the horse looks worse after, giving the vet a much higher level of clinical suspicion that our pain or the issue is coming from that region. Think of it as if you are sitting in one position too long, especially those of us that are getting older and having maybe some arthritis or some stiffness in our own joints, and you get up and you’re really sore and not able to walk it off right away. A flexion test is similar. “Certainly, there are horses that don’t take any bad steps after a flexion,” Dr. Robinson says. “That horse would be, in my opinion, completely normal in that region, whereas the horse that takes a couple of slightly off steps and they’re an 18-year-old campaigner, they’re probably going to have some positive flexion.”

In my horse’s case, after the flexion test the treating veterinarian declared him a 4 out of 5 on the injured leg. But he was also 1 out of 5 on his “good” leg after flexion.

Given what I know now, his age and the fact that he has not had any joint injections or supplements can account for his positive flexion test. “If the horse is moving well before the flexions on that particular leg, and it’s a very mild, positive response to the flexion, we’ll note it, as it’s important for the horse’s record, but not necessarily something to stress about,” says Dr. Robinson, who was not the vet who treated my horse.

As I wait for my horse’s injury to heal, I keep watch on his tracking up and have observed his footfalls at the walk have improved. Still, I don’t fool myself that I can pick up on subtle lameness. And as Dr. Robinson says, I shouldn’t be too hard on myself. “We veterinarians are looking at a lot of different things when we are assessing a lameness,” she adds. “And it takes us years and hundreds if not thousands of lameness exams to develop our eye for all the things that we can see.”