Cover Story | Orthopedics

Assessing Complicated Lameness

By Marie Rosenthal MS

Keep an open mind when determining the cause of a complicated lameness case because the issues affecting the horse are often multifactorial, and the lameness can be subtle, even if multiple limbs are affected, according to Jodie Daglish, BVSc, MS, DACVSMR, MRCVS, a veterinarian at NEH Cotswolds, a specialist sport horse practice in the United Kingdom.

“The questions become: When are these cases limiting the horse’s ability to perform? And when are they struggling with other issues?” she asked at the AAEP Annual Convention, held in San Diego.

The horses often are brought with a complaint of poor performance or a behavioral issue,” which often is just the horse trying to communicate its discomfort.

“When horses are presented to me for performance issues, they’re often horses that have lost the ability to perform at a level that they previously were easily attaining. And if these horses have been achieving these tasks, they may now be struggling in that ability on one rein versus another.

“Or there may be horses that are struggling to attain the next level of training,” she said. Often, they are horses that used to have a good attitude toward their work and now, their attitude has changed, and they are unwilling to perform. Sometimes, they are labeled as inherently ‘bad,’” she said.

“They fundamentally have reasons to behave this way. And so, they may be showing us exaggerated responses to tasks they should be able to achieve. And that can be things like exploding after a jump—shooting off like they’ve been stung by something—or simply being grouchy about being tacked up. In other horses, we may see a visible deterioration in their condition; they may be losing muscle mass. They may have asymmetries, or they may just look poor in their coats, which could be an early warning sign [of a physical problem].

“And if you’re dealing with young and developing horses, they may also be showing an inability to reach a level of work that we would expect them to easily attain for their body type and condition,” she said.

Dr. Daglish laid out her approach to evaluating these horses. The goal is to determine whether the issue is associated with an active disease process due to muscular pain, perhaps because they are overcompensating for pain somewhere else, or whether there is a biomechanical problem.

As with any assessment, the history is paramount, and it is important to talk to several people involved in the care of the horse from the owners, rider and trainer to the farrier, groomer and referring veterinarian. You want to know:

• Exactly what the horse is doing and when?
• Do the behaviors just occur when it is being ridden or are they also displayed when it’s being groomed or tacked up?
• Are they overreacting to normal activities like a brush going over the spine?

The answers to these types of questions could give you an idea of where to begin your search for an answer, she said, because many areas of the body could be involved, not just the limbs.

“I always pay attention to their previous veterinary assessments,” she said. “I want to know what were the previous lameness issues. Are these recurring? When were they last treated? Were they treated in a way I think would be effective?”

Sometimes changing the treatment can make a difference for the horse; for example, maybe it was taking a non-steroidal anti-inflammatory, but it needs gabapentin to address nerve pain. “It’s not always about reinventing the wheel; it’s about changing the approach to that same wheel,” she said.

A good farrier can give you a lot of information. Does the horse manage to maintain its balance when the forelimb is off the ground? Does it struggle to have a hindlimb lifted? Does the horse try to resist the farrier when they are nailing on the shoe?

And did the horse respond positively if it received care from chiropractors, physiotherapists, osteopaths or massage therapists? Does the issue recur?

Finally, owners, trainers and riders can contribute by explaining when and how the behavior manifests, particularly if associated with specific circumstances.

“On my clinical examination, I try to see the horse at liberty in the stable, so I can assess their posture and their stance,” she said.

She looks at bony prominences. Are they in the places they should be, and are they symmetrical?

Look for muscle symmetry and atrophy, and palpate for swellings, soft tissue changes, sensitivity and warmth.

“Pay attention to foot balance and the shoeing style,” she said, as well as the quality of the horn.

“As part of my general exam, I include passive range of motion [exercises], and I’m looking at how symmetric movement is between left and right limbs. And whether that movement is normal, restricted or reactive,” she said.

“Most importantly, I look for how the limbs move proximally. Does protraction and retraction of the forelimb occur readily, and is the horse comfortable and happy for me to do that? How does the thoracic limb move over the body wall? A horse should be able to move with those forelimbs easily over the body wall,” Dr. Daglish said.

Palpate the cervical spine and the soft tissue along the topline to look for “trigger points.”

“Now, it is not specific; it is not going to tell you it’s a forelimb lameness versus thoracic spine pain versus lower neck pain. But it gives you an area to focus on, and ultimately, you’re creating a problem list for yourself,” she said.

She will protract, retract and move the limbs. She wants to know how the horse reacts. Is it okay with her picking up and holding the leg? Or does it pull it back and slam it back down?

Evaluate the thoracolumbar spine by applying slight pressure on the individual spinous processes, to the ligament structures over the bones and palpate the epaxial muscles. Is the horse painful when you put pressure on any of these areas?

When she examines the pelvis, she is measuring the response to tuber sacrale compression, tuber coxae push, caudal tail traction, and/or lumbosacral tuck and hindlimb circumduction. Are they “smooth and controlled and relaxed? If the movement is exaggerated or sharp, that could mean the horse is painful acutely. But if it’s reduced, and the horse doesn’t move, that doesn’t mean he’s normal, that means he’s guarding and could reflect hypertonicity in the muscles as a protective mechanism observed with more chronic pain states,” she explained.

During the dynamic examination, she is looking for aberrant gaits and obvious signs of lameness, as well as compensatory muscle pain, which can be present.

“For my lameness cases, I look at them at walk, trot and canter, and I’ll obviously watch them on a soft surface circle at trot and canter, and then I’ll watch them on a hard circle at trot. But I do also make sure that I’ve seen them walk and turn left and right. I want to see if these movements look normal.”

She watches the horses posture; when it moves in a circle, does it tilt its head to the outside? Does the horses movement exaggerate or mask a subtle asymmetry in its gait pattern?

“As sports medicine clinicians, we love the ridden exam,” Dr. Daglish said, adding she likes to have the owner or rider demonstrate the behavior, rather than a technician. Often, however, riders are reluctant to get on the horse. That should make you consider the severity of the problem. In those cases, she will ask for videos, because many owners take videos these days. Watching them in slow motion can give you a good indication whether it is safe for anyone to ride the horse during the examination.

If the rider, rather than a technician, is willing, have them perform the exercise that is most likely to get the concerning reaction. Sometimes this is generalized and sometimes may be specific to one movement in one circumstance.

She suggested using Dr. Sue Dyson’s Pain Ethogram, which lists behaviors and facial expressions that signal musculoskeletal pain.

And diagnostic anesthesia may resolve these issues. She said it is important to be systematic about the use of diagnostic anesthesia, including performing diagnostic anesthesia with the patient ridden to assess response.

Look at the saddle fit and how the rider sits in the saddle. Is the rider straight or wonky? Are they exacerbating the horse’s abnormalities? Have the rider exercise the horse in a contact and on a loose rein; does the response vary?

“Treatment is not going to be effective if it targets the wrong thing,” she said, so it is often useful to use one of the many technologies that can help you sort through the problem without bias.

Technologies
There are a lot of technological advances that can help a veterinarian diagnose the problem. They will never replace veterinarians, but those “who use it, integrate it within their practice and embrace advancing technology available to us” will replace those who are reluctant to do so, because they not only help the diagnostic differential, but owners expect it today.

Wearable technology is becoming popular. “Gait analysis technology is becoming increasingly available, and I think a lot of people are being more open-minded about using these. These tools use body-mounted inertial sensors, and there is increasing research into similar additional tools that may benefit assessment of pain.

“There was a survey recently performed where 60% of the respondents were more than 10 years graduated. And of those, 50% used the system in about a quarter of their cases. Now, there was a mixed bag of ambulatory and clinic-based veterinarians within respondents. You can use them wherever you are really. Typically, people are using the gait analysis technology for mild-to-moderate lamenesses, especially if there are multiple limbs affected based on the research presented by Hardeman and colleagues.

“The objective gait assessment tools, such as the Lameness Locator, are particularly helpful for documentation of a response to blocking. I think this is important because we’re all biased, especially when we have naughty horses to work on,” she said.

Kinetics look at how forces act on a body, but as this technology requires force plates with specific recordings it is not practical outside the university or research clinic setting.
Kinematics, which is the study of the body’s movement, are a little bit easier to transfer and use in the clinical environment. “It’s the study of movement of the body and limb characteristics through the stride phases. Anyone with a smartphone can take a video and play it in slow motion, and you can look at how those limbs move in space,” she said. There are also apps that are more sophisticated that can be useful for this practice.

She discussed 3 advanced imaging modalities: nuclear scintigraphy, magnetic resonance imaging (MRI) and computed tomography (CT).

Although “not everyone loves nuclear scintigraphy,” it can be useful in identifying stress fractures. Its use is somewhat contentious because it may be less sensitive and specific for general imaging of the sports horse.

“It can be a Pandora’s box. Once you start looking, you can’t put things back in that box, can you? And it has a high number of false positives, being not as specific and sensitive as it previously was thought. Therefore, it’s imperative that it’s performed alongside a thorough clinical evaluation and diagnostic analgesia,” she said.

“You must be confident that what you’re looking at fits with what you are seeing clinically,” Dr. Daglish said. And you need to know what is normal for that animal to tell what is abnormal.

Images from MRI are beautiful, she said, and almost everyone loves to include MRI in cases with subtle findings.

“I find it’s most effectively employed in my poor performance or subtle lameness cases where a radiographic or ultrasonographic diagnosis hasn’t been attained despite reaching a specific blocking response or where the primary imaging findings are not commensurate with the degree of lameness,” she said.

“If this horse is really lame, and I’m finding pretty subtle stuff, then I’m missing something and I want to know what that is before I send it out to do work or start rehabbing it,” she said. If she’s covered all her bases and standard treatment for an injury has failed, then MRI might help her to uncover the underlying problem.

“MRI has hugely advanced our ability to interpret ultrasound of different regions, but particularly the proximal suspensory ligament. So, as practitioners out there, I would encourage you to go and look at those papers and, use those to help you with your proximal suspensory ultrasound technique and interpretation.”

It is most valuable in finding subtle issues and early disease processes, which when caught early have a better chance of recovery, according to Dr. Daglish.

Veterinarians are increasingly reaching for CT to diagnose issues with the head, neck and spine. They have also been used in the distal limb and stifle and may provide additional information for complex fracture repair and for delineation of some soft tissue injuries such as cruciate ligament injury or complicated tendon injury within the foot.

“For me CT is particularly helpful in the lower neck and it’s the only pre-mortem modality that will help us reach a comprehensive diagnosis for caudal cervical spine issues in and around the cervicothoracic junction. For those horses with arthropathy, foramen stenosis or radiculopathy I think that CT is invaluable, and I wish that I had an easier access to one than I currently do,” she said.

The important thing is to be systematic and thorough in the approach to these challenging cases, according to Dr. Daglish. “Generate a problem list that looks at standard lameness, the axial skeleton issues that you may be identifying, and also medical issues, which [might cause] subtle lameness or performance issues.”

You are putting together a jigsaw puzzle of bits of information to make a complete picture.

“Remember to interpret your findings relative to what the owner presented the horse for. This is really important. A lot of people get very swayed by a single limb lameness, for example, but if that’s not relevant to the fact that the horse is bolting with the owner every time they jump it, then you’re not dealing with the issues that they’ve presented it to you to address,” she warned.

And don’t be afraid to pick up the phone or to email a colleague and get another opinion, she suggested. “The issues we are dealing with are complicated cases. Don’t be afraid to ask for help.” MeV

For more information:
Hardeman AM, van Weeren PR, Serra Bragança FM, et al. A first exploration of perceived pros and cons of quantitative gait analysis in equine clinical practice. Equine Vet Educ. 2022;34:e438–444.
https://beva.onlinelibrary.wiley.com/doi/full/10.1111/eve.13505