Guelph, ON – July, 31, 2025 – Dr. Taralyn McCarrel’s journey into equine lameness began with her early experiences riding and working at a hunter barn. Recognizing the critical importance of soundness for both horses and riders, she developed a keen eye and ear for detecting lameness issues. Her passion for veterinary medicine led her to graduate from the Ontario Veterinary College in 2006. McCarrel specialized in large animal surgery and lameness diagnosis during her residency in Kentucky, where she gained extensive experience with racehorses and sport horses. McCarrel’s dedication to equine well-being continues to drive her work to this day as Associate Professor, Large Animal Surgery at the Ontario Veterinary College.
Working in referral hospitals has seasoned McCarrel to managing complex cases, often requiring advanced imaging and a nuanced approach to diagnostics. She highlights the importance of knowing when to use various diagnostic tools and offers clients options for either rapid, comprehensive diagnostics or a more stepwise, cost-effective approach. “I love being in an environment where I have all the toys to use when needed,” says McCarrel. “I think one of the advantages of being in environments where you’ve had access to all of these things, is learning when to use what.”
Common or Complex Lameness
The most common lameness issues vary by equine disciplines and breed. McCarrel notes that her experience may be slightly skewed, with her clients coming from referrals, but for most horses she sees, foot problems are the predominant cause of lameness. “The saying ‘no foot, no horse’ holds true,” says McCarrel.
In contrast, younger racehorses typically come in with more limb-related lameness, including issues with the fetlock, carpus, suspensory, and stifle. The foot problems seem to turn up in slightly older equines.
In her practice, McCarrel also frequently encounters upper body issues like neck, back, and pelvis problems, which may coincide with limb lameness. These cases often require advanced diagnostic imaging to accurately diagnose and treat.
Down to Diagnostics
MRI has been revolutionary in accurately diagnosing foot lameness. High-field MRI, the gold standard for imaging the soft tissues of the foot, provides cross-sectional imaging (showing thin slices of the imaged tissues) of the soft-tissue and boney structures of the foot and provides both anatomic and physiologic information about those tissues. “Interestingly, we still encounter horses with foot pain and unremarkable MRI results, making them particularly frustrating to treat,” says McCarrel. “There’s ongoing discussion about whether we need to pay more attention to the digital cushion in MRI scans. Are there changes in this tissue that we’re not recognizing in horses with unclear lesions that explain their lameness? In some cases, the issue might be related to the quality of their hoof and the angles at which they are trimmed and shod.”
Digital radiography has significantly improved, allowing field practitioners to obtain high-quality X-rays of the back, identifying conditions like kissing spine lesions. These advancements enable more precise diagnostics, although some cases still require further investigation to determine the exact cause of lameness.
Transrectal ultrasound of the pelvis is relatively new innovative tool, allowing for better imaging of the pelvis by using sound waves from an ultrasound probe inserted via the rectum. The different densities of tissues (such as bone, muscle, and ligaments) reflect sound waves differently, allowing the veterinarian to visualize these structures in detail. This method has helped identify conditions like nerve compression at the lumbosacral joint and assess the health of the sacroiliac joint and intervertebral discs. McCarrel provides an example where she was able to diagnose a senior horse who presented as unwilling to hold his leg up for the farrier when they found nerve root compression using transrectal ultrasound after ruling out sources of pain elsewhere in the limb.
“Our ability to image the pelvis, in adult horses, has been quite limited,” says McCarrel. “With improvements in X-ray technology, we can get better X-rays but there’s still some areas we do not see well. Bone scans give you an idea of an area that has high bone turnover, but it doesn’t tell you specifically what the problem is. By ultrasounding the pelvis from the inside, you can see much more of the pelvis and if you combine that with ultrasound of the pelvis from the outside as well, we get a more comprehensive view.”
Large Bore CT units have been an amazing step forward in imaging, enabling detailed scans of many areas standing, as well as imaging of larger areas under anesthesia including the stifle and all the way down to the base of the neck. These advancements have led to more accurate diagnosis and new surgical procedures that can significantly improve the quality of life for affected horses. One such example is nerve root impingement in the neck and the recently developed procedure to alleviate the compression of the nerve and associated pain.
PET (Positron Emission Tomography) imaging, often combined with CT scans, provides a powerful new way to assess bone and tissue activity in 3D. Unlike traditional imaging that shows structural damage like fractures, PET scans highlight areas where bone or soft tissue is actively changing or remodeling. This makes it especially useful for detecting subtle or early-stage issues that might not yet be visible on standard scans. While similar in concept to bone scans—where a small amount of radioactive material is used to track bone activity—PET imaging offers more precise and localized information. However, access to PET-CT technology is currently limited and can be costly, so its broader use in veterinary medicine is still evolving.
Gait Analysis is entering a New Era with AI
Dr. McCarrel highlights gait analysis systems as an exciting area of development in equine care that is in its infancy. Unlike traditional imaging tools like X-rays or CT scans, gait analysis doesn’t produce images—it tracks how a horse moves. One well-known system, the Lameness Locator, has been used for years at the Ontario Veterinary College (OVC) to help detect subtle signs of lameness. While effective in some cases, it has its limitations.
“While gait analysis systems have been valuable tools for detecting lameness in horses, they aren’t perfect,” says McCarrel. She explains these systems work best when horses trot in a straight, consistent manner. However, if a horse moves irregularly—such as turning its head or shifting weight unevenly—the system may not recognize these subtle changes, leading to inconsistent results.
Newer systems using artificial intelligence aim to improve accuracy by analyzing more complex movement patterns and adapting to each horse’s unique way of moving. These AI tools may eventually help identify early signs of injury risk or even guide training to prevent injuries. However, they’re still in development, and more research is needed to determine how reliable they are for one-time diagnoses versus ongoing monitoring. These systems could prove especially valuable in the racing world, where early detection of movement irregularities could help identify horses at risk of injury before problems become serious.
New Frontiers in Lameness Treatment: Orthobiologics and Beyond
McCarrel highlights several promising advances in the treatment of equine lameness, particularly in the field of orthobiologics—therapies that use the body’s own biological materials to support healing.
These include:
- Stem cells (or more accurately, mesenchymal stromal cells), which may help repair damaged tissues.
- Platelet-rich plasma (PRP) and other platelet-based products, which use components from the horse’s own blood to promote healing.
- IRAP (Interleukin-1 Receptor Antagonist Protein), which helps reduce inflammation in joints.
- A2M (Alpha-2 Macroglobulin), a newer treatment that may help protect cartilage from damage.
Dr. McCarrel points to a recent study comparing several of these treatments, which found that some combinations—like PRP and autologous protein solutions—may contain higher levels of beneficial proteins like IRAP and A2M than expected. These findings help clarify how these treatments work and may guide more effective use in the future.
In addition to biologics, new handheld shockwave therapy devices are making treatment more convenient and accessible. These smaller, quieter units could improve ease of use for veterinarians and comfort for horses.
Beyond treating injuries, Dr. McCarrel sees growing potential in using physical training to help prevent them in the first place. Targeted exercises can improve a horse’s balance and muscle development—key factors in reducing injury risk.
“What we really want to understand is how physical training can prevent injuries—not just help horses recover from them,” says Dr. McCarrel. “Having done a back-strengthening program with my own horse, I know how time-consuming it can be, but the changes in muscle tone and balance are real. I think this is going to be a major area of growth in equine care.”
Understanding Risk and Acting Early: Keys to Managing Equine Lameness
When it comes to diagnosing lameness in horses, McCarrel emphasizes that both common and complex cases benefit from a combination of advanced tools and experienced clinical judgment. But just as important as diagnostics are the risk factors that can lead to lameness in the first place.
“We know that age, body size, and excess weight all increase a horse’s risk of developing lameness,” says Dr. McCarrel. “Foot conformation and hoof care are also critical—imbalances in the hoof can put strain on tendons and joints, especially in the heel area.”
Other key risk factors include:
- Developmental orthopedic diseases, which may or may not impact soundness depending on severity.
- Poor footing or uneven surfaces, which can stress joints and soft tissues.
- Endocrine disorders like Cushing’s disease or equine metabolic syndrome, which can lead to chronic laminitis, sometimes without obvious signs.
McCarrel also stresses the importance of early intervention. Subtle lameness issues, if left unaddressed, can lead to a cascade of secondary problems that are harder to treat.
“It’s always better to catch a small issue early than to wait until it becomes a big one,” she explains. “In some cases, like tendon injuries or undiagnosed fractures, early detection can make a huge difference in prognosis—and in safety for both horse and rider.”
Looking Ahead
As diagnostic tools and treatment options continue to evolve, so does our understanding of equine lameness. From cutting-edge imaging technologies to biologic therapies and AI-driven gait analysis, the future of equine care is increasingly proactive and personalized.
With continued research, collaboration, and innovation, veterinarians and horse owners alike are better equipped than ever to support long-term soundness and performance in horses across all disciplines.
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Notes to Editor:
Equine Guelph is the horse owners’ and care givers’ Centre at the University of Guelph in Canada. It is a unique partnership dedicated to the health and well-being of horses, supported and overseen by equine industry groups. Equine Guelph is the epicentre for academia, industry and government – for the good of the equine industry as a whole. For further information, visit www.equineguelph.ca.
Story by: Jackie Bellamy-Zions, Equine Guelph
Photos: (images available upon request). Lameness Lab button and Sport horse lameness course graphic.
Web Link(s):
Story web link: https://thehorseportal.ca/2025/07/what-diagnostics-are-available-for-common-and-complex-equine-lameness/
Other web links:
Video interview withDr. Taralyn McCarrel: https://youtu.be/PKFkaudmrkE
Link to Dr. Taralyn McCarrel’s bio: https://www.uoguelph.ca/ovc/clinical-studies/faculty/taralyn-mccarrel/
Link to Lameness video challenge: https://thehorseportal.ca/healthcare-tools/lameness-lab/
TheHorsePortal.ca courses: https://thehorseportal.ca/courses/
Media Contact:
Jackie Bellamy-Zions
Communications
Equine Guelph
Guelph, ON N1G 2W1
519.824.4120 ext. 54756
jbellamy@uoguelph.ca