Deciphering Multilimb Lameness in Horses

Learn how veterinarians get to the bottom of this complex cause of poor performance.
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veterinarian watching horse under saddle
Due to the added biomechanical loads and complexity of exercises a rider introduces, multilimb lameness can be much easier to detect under saddle than in-hand. | Erica Larson/The Horse

Learn how veterinarians get to the bottom of this complex cause of poor performance

It might start as a performance issue. You notice your horse is just a little “off,” not wanting to take certain turns or lacking power over fences. Or maybe he can do medium trots but no longer wants to do collected trots, or she’s making wide turns around the barrels.

While poor performance can have multiple causes, multilimb lameness—pain in two or more limbs—might be the culprit.

But unlike a single-limb lameness, which often presents as a well-recognized head-bob or hip-hike, multilimb lameness can be complicated to recognize, diagnose, and explain.

“Most riders don’t recognize it (as lameness), but they can appreciate that they’ve got a problem,” says Sue Dyson, MA, Vet MB, PhD, DEO, Dipl. ECVSMR, FRCVS.

To diagnose and, ultimately, treat multilimb lameness, owners and veterinarians must collaborate to focus on the signs and causes, she says.

Poor Performance: The First Clue

Horses with multilimb lameness rarely look “classically” lame, explains James Bailey, BVetMed, FHEA, MRCVS, clinical assistant professor in veterinary sports medicine at the University of Nottingham’s School of Veterinary Medicine and Science, in the U.K. “You’re looking for mild performance issues a lot of the time,” he says.

Horses might not only resist certain movements but also shake their heads or gape their mouths. “It really throws into question all those horses that historically were dismissed as naughty or unrideable and dismissed from certain levels of activity,” he says.

In fact, horses with lameness in two front or two hind limbs in particular can “sort of shuffle … without red flags,” he says. The only sign might be poor performance or stride lengths shortened by about 5%—which is barely noticeable. “These are the ones that really creep up on you,” he says.

“Many people blame the horse’s performance on a training issue or the horse not being cooperative or the horse being difficult, rather than seeking advice as to asking why the horse is being difficult,” Dyson adds. “So the first major step is to ask why and seek help.”

The Critical Importance of Recognizing Expressions of Pain

Not all performance issues can be attributed to multilimb lameness, of course. So how do we know it’s lameness and not a lack of talent?

Dyson says body language can be a key component. “It’s here that the ridden horse ethogram comes into play,” she says.

Over the past six years Dyson and her fellow researchers have been developing and perfecting the ridden horse pain ethogram (RHpE). Their study results have shown that horses displaying at least eight of the 24 pain-related behaviors they’ve identified on their checklist—such as pinning the ears back for at least five seconds or opening the mouth and separating the teeth for at least 10 seconds—are highly likely to have underlying pain.

If horses struggle just because they lack athletic ability, they won’t show as many signs in their body language, Dyson says.

As for young horses that have not yet had the chance to show their full potential, they should follow a gradual path of progression, given appropriate training and conformation, Dyson says. And while a one-sided preference might be acceptable in the short term, it shouldn’t be a long-term issue, she says.

“Some people say, ‘Oh, well, I need to take this horse slowly, because it’s an immature horse,’” she says. “And before they know it, they’re three years down the line, and the horse hasn’t progressed at all. And the reason is that it’s had underlying discomfort all this time.”

The RHpE points to general musculoskeletal pain in these horses, meaning it doesn’t specify where in the body that pain is coming from. Therefore, multilimb lameness remains one of several possibilities, and further diagnostic work-ups are necessary, Dyson says.

Best Diagnosed Under a Rider

Due to the added biomechanical loads and complex exercises a rider introduces, multilimb lameness can be much easier to detect under saddle than in-hand, says Dyson. “With the majority of horses with lameness in more than one limb, lameness is consistently more apparent ridden,” she says.

Good diagnostic opportunities come from performing exercises that are more biomechanically demanding than working along the arena perimeter, Dyson says. Veterinarians should watch from the front, back, and sides as the horse moves across a long diagonal in all gaits. Riders should also perform 10-meter-diameter circles in rising trot and larger circles in a canter in both directions.

Circles are particularly important because pain in both front or both hind limbs can make a horse appear sound when moving straight, Bailey explains. “You start to appreciate that the horse looks lame on the left front leg on the left circle but looks lame on the right front leg on a right circle—even though in a straight line the horse could be completely symmetrical,” he says. “That’d be a classic case of multilimb lameness, and you’re only going to see it when you move that horse away from a straight line.”

Lameness at the trot might be characterized by head-bobbing, shortened strides or reluctance to perform, Dyson says. At the canter, veterinarians should look for “a stiff, stilted canter or a four-beat canter.” During transitions veterinarians should see if the horse flexes the lumbosacral joint and steps under with the hind limbs as he should or if he fixes his back and takes short steps ­behind—especially for downward transitions. “That’s usually a reflection of discomfort,” she says.

The veterinarian also needs to see different riding scenarios: with and without rein contact, for example, and sitting one diagonal versus another, as many hind-limb lamenesses are worse when riders sit on the diagonal of the lamer limb, she says.

Even so, it’s important to keep in mind that some riders can effectively conceal lameness through subtle cues that re-balance the horse, without realizing they’re doing it, Dyson adds. In such cases, riding with loose reins or having someone else ride the horse might be useful for diagnostic purposes.

Importantly, recognizing lameness in a ridden horse is a skilled art, she says. “We have to educate veterinarians about how to watch a ridden horse.”

The Limb That Sets Off the Search

When poor performance and painful body language haven’t given clear enough clues, owners tend to eventually notice more obvious lameness in a single limb, Bailey says. Single-limb lameness is sometimes secondary to more subtle multilimb ­lameness—with the horse compensating for, or adjusting to, discomfort in multiple legs, to the point of creating injury in one of the limbs.

“That’s quite a common picture, actually, that owners will come in with a lameness on one limb,” he says. “And we block that out (with diagnostic analgesia, or nerve blocks), and all of a sudden we see some other bits and bobs creeping in, which were obviously masked by the more severe problem that sort of struck (the owner) at first.”

This can come as an extreme surprise to owners, he adds. “They’re obviously very shocked and saying, ‘What have you done?’” he says. “But the horse was clearly that lame on both limbs, and we’ve just made one of them feel better.”

The Basic Physical Exam

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A multilimb lameness work-up starts with a standing physical examination, says Dyson. “I’m going to be looking at how well muscled the horse is and if he’s got a good topline and neck,” she says. Poor musculature in the lumbar and pelvic regions suggests the horse “has not been moving through its back … which generally reflects a hind-limb problem.”

She also assesses the horse’s reaction to picking up a single limb and flexing it, checking whether the horse “resents” these moves and whether the back muscles show tension or pain. “Horses, being prey animals, like to disguise their discomfort, and they can do that very cleverly by reducing range of motion of the back,” she says. “By stiffening the back, they disguise the fact that they are uncomfortable.”

Nothing Beats a Good Nerve Block

While physical exams can be helpful, the most useful diagnostic tool for multilimb lameness is nerve blocking, our sources say. By deadening any sense of pain in specific regions of the leg or foot, nerve blocks are “the only way to determine reliably where the sources of pain are,” Dyson says. In fact, she says she sometimes has to block nerves in three or four legs to find the source of the problem.

Correctly placed nerve blocks can make a lame horse sound, to the point of revolutionizing the way a horse feels under saddle, she explains. “The rider will say, ‘Wow, this horse feels completely different.’

But nerve blocks aren’t always the go-to when it comes to diagnosing lameness, because some clients object to it as a first-line option, says Bailey. “Owners will sometimes say, ‘Why can’t we just take some X rays?’ or ‘Why can’t we just scan this?’ or ‘Why can’t we just do that?’” he adds.

“The honest answer is that if you image the entire horse, you’re going to find things that look abnormal, like a little bit of arthritis in the coffin joint or a little bit of change at the proximal suspensory ligament,” he says. “It could be any one of those things. And I’ve just spent 1,000 pounds (more than $1,200) on imaging to tell you your horse has got all these things. But without blocking it, I don’t know which one’s the culprit.”

Dyson agrees this “fishing expedition” is rarely beneficial. The pathologies (disease or damage) imaging technologies pick up on don’t necessarily create lameness or pain, she says. “Without doing nerve blocks, you’re just guessing.”

Despite their advantages, though, nerve blocks in unskilled hands can be both time-consuming and dangerous, she warns. Placing a needle very close to a precise nerve requires patience and experience, and horses can react violently—especially with their hind limbs. “You’ve got to position yourself strategically out of aim of a kick,” says Dyson, adding that she always wears a helmet during such procedures.

Even if the horse doesn’t react negatively at first, blocks can cause behavior and safety issues if the horse starts to resist the procedure, Dyson explains. Thus, veterinarians should start by selecting the region most likely to be affected—often a front forelimb—while maintaining a positive interaction with the horse.

“In my experience, when these horses are handled appropriately, they actually become progressively more accepting of the restraint required and the nerve blocks,” she says. “But it does take a certain quiet way of approaching the horse and positive reward for good behavior in order to be successful.”

After Blocking, Then Imaging

Once nerve blocks have pinpointed the troublesome areas of the limbs, radiographs and ultrasound—or, if needed, more advanced procedures such as computed tomography (CT), MRI, or scintigraphy (bone scans)—can help veterinarians see the pathologies contributing to lameness, our sources say.

In cases of multilimb lameness, that can mean multiple rounds of blocking and imaging, as each new block reveals new lameness issues, Bailey says. “I warn owners that we might be here a little while, so if you want to go get a coffee, get a coffee. But I also reassure them that we’re managing this. The idea is that we’re selecting whatever is the most significant thing each time and monitoring the response to (blocks or treatment) as time goes on.”

What Causes Multilimb ­Lameness?

While breed (and associated conformation) and discipline certainly play roles, suspensory ligaments seem to be primary culprits in modern multilimb lameness issues, Dyson says. In other cases, pain in both front limbs is often centralized in the feet—due to podotrochlosis (aka navicular disease) or coffin joint arthritis, for example.

“(Front) fetlocks are very commonplace as well, but they’re almost specific to racehorses because of that repetitive loading,” Bailey says.

As for the hind limbs, bilateral (affecting both sides) lameness is usually due to pain higher than the fetlock, and it might be due to distal (lower) hock joint arthritis in Icelandic horses, stifle pathology in reining Quarter Horses, or a variety of other sports-specific issues.

In general, the origins of multilimb lameness are usually gradually developing pathologies, as opposed to the traumatic events that often cause single-limb lameness, such as a kick from a pasturemate, Bailey says. “At the end of the day, a horse’s left foot has done just the same number of miles as his right front foot,” he says. “So when we’re dealing with arthritic changes or degenerative ligaments, it makes sense that they’re likely to affect at least both legs left and right, if not back and front as well.”

Inbreeding, especially among Warmbloods in the past three decades or so, probably contributes to multilimb lameness, Dyson says. “We’ve bred for extravagant movement (rather than longevity) preparing them for dressage or upper-level show jumping,” she says. That, combined with extensive, early single-discipline training on artificial surfaces and genetic predispositions, could put these horses at greater risk.

Take-Home Message

Multilimb lameness is, by definition, pain in two, three, or all four limbs. Yet it often appears far less obvious than pain in a single limb. Understanding the causes of multilimb lameness and how it manifests—often as subtle performance issues—can lead not only to better health and welfare but also improved performance.

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Passionate about horses and science from the time she was riding her first Shetland Pony in Texas, Christa Lesté-Lasserre writes about scientific research that contributes to a better understanding of all equids. After undergrad studies in science, journalism, and literature, she received a master’s degree in creative writing. Now based in France, she aims to present the most fascinating aspect of equine science: the story it creates. Follow Lesté-Lasserre on Twitter @christalestelas.

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