By Dr Jason Lowe BVSc
Understanding Hock Lameness in Horses
Hock pain is one of the most common causes of poor performance and hindlimb lameness in horses. Whether your horse competes in dressage, eventing, showjumping, racing, reining, cutting, campdrafting or pleasure riding, healthy hocks are essential for impulsion, collection, engagement and athletic longevity.
The equine hock (tarsus) is a unique joint complex consisting of both high-motion and low-motion joints. While all can become diseased, the vast majority of chronic performance-related hock lameness originates from the distal intertarsal (DIT) and tarsometatarsal (TMT) joints, commonly referred to as the “lower hock joints.” These joints are particularly prone to synovitis, capsulitis and osteoarthritis (OA).
For decades, veterinarians have focused primarily on controlling inflammation and managing pain. Today, however, our understanding of joint disease has evolved significantly. We now recognise that preserving synovial membrane function, minimising capsular fibrosis and maintaining healthy joint biology are critical to sustaining long-term performance.
This shift in thinking is one reason why Arthramid® has become an increasingly important treatment option in equine hock disease.
What Are the Signs of Hock Arthritis?
Horses with pain in the lower hock joints rarely present with dramatic swelling. Instead, the signs are often subtle and progressive.
Owners and riders frequently notice:
- Reduced impulsion
- Shortened hindlimb stride
- Difficulty engaging from behind
- Reluctance to collect
- Difficulty with flying changes
- Poor performance on circles
- Resistance during transitions
- Reduced willingness to work “through the back”
A classic finding is that the lameness becomes more apparent when the affected limb is on the inside of a circle. Many horses also demonstrate an exaggerated response to full limb flexion.
As many riders describe it:
“My horse just isn’t pushing from behind like it used to.”
One of the challenges with hock disease is that outward signs can be surprisingly limited despite significant pain and loss of performance.
Why Hock Arthritis Can Be Difficult to Diagnose
Modern research has shown that there is often a poor correlation between radiographic changes and the degree of pain experienced by the horse. Horses can demonstrate obvious lameness despite relatively mild x-ray findings, while others have extensive radiographic arthritis but remain surprisingly comfortable.
Diagnosis typically involves:
- Clinical examination
- Gait assessment
- Flexion tests
- Diagnostic analgesia (joint blocks)
- Radiography
- Ultrasound
- Advanced imaging such as MRI, CT or scintigraphy when necessary
Intra-articular analgesia remains the most accurate method of confirming hock pain and distinguishing hock disease from other causes of hindlimb lameness such as proximal suspensory desmitis.
Importantly, advanced imaging studies have shown that significant pathology may be present even when conventional imaging appears relatively unremarkable.
The Real Problem: Synovitis and Capsulitis
Historically, equine osteoarthritis was viewed primarily as a disease of cartilage.
We now know that this is only part of the story.
Research increasingly demonstrates that chronic inflammation of the synovial membrane (synovitis) and joint capsule (capsulitis) plays a major role in generating pain, restricting motion and driving progression of osteoarthritis.
In the lower hock joints, synovitis and capsulitis are particularly common in athletic horses and frequently occur before severe radiographic osteoarthritis develops.
This explains why many horses improve significantly following joint therapy despite having relatively modest x-ray abnormalities.
Understanding Hock Osteoarthritis
Osteoarthritis of the distal intertarsal and tarsometatarsal joints is one of the most common conditions seen in equine practice.
Radiographic changes may include:
- Bone spurs (osteophytes)
- Enthesophyte formation
- Joint space narrowing
- Subchondral bone sclerosis
- Bone lysis
- Progressive joint remodelling
As disease progresses, the joints may become increasingly painful and less responsive to traditional therapies. In severe cases, treatment discussions may include facilitated fusion (arthrodesis) of the lower hock joints.
However, the goal should always be to identify disease early, intervene appropriately and preserve joint function for as long as possible.
How Arthramid® Is Changing the Management of Hock Arthritis
Arthramid® represents a different approach to managing equine osteoarthritis.
Rather than acting solely as a traditional anti-inflammatory medication, Arthramid® is a 2.5% injectable polyacrylamide hydrogel (iPAAG) that integrates into the synovial membrane and periarticular tissues following injection.
Over approximately 1-2 weeks, the hydrogel becomes incorporated into the tissue, forming a durable biocompatible support matrix that helps reinforce the joint lining and support healthier synovial membrane function.
This mechanism aligns closely with what we now understand about the biology of osteoarthritis, namely that maintaining healthy synovial tissues may be just as important as managing cartilage pathology.
The result is often:
- Reduced joint pain
- Improved comfort
- Better mobility
- Enhanced performance
- Longer periods between treatments
- Improved long-term management options
Clinical Results with Arthramid® in Hock Disease
One of the largest reported clinical experiences with Arthramid® in equine hock disease comes from a multicentre UK case series involving 497 lower hock joints (295 TMT and 202 DIT joints).
Key findings included:
- 88.9% of treated joints were sound within 2 months
- Approximately 61% of horses remained in work for more than two years following treatment
- Only a minority required additional therapies during that period
These results are particularly impressive given that lower hock osteoarthritis is commonly considered a lifelong disease requiring ongoing management.
The findings also support what many veterinarians now observe clinically: that treatment of hock synovitis and osteoarthritis can be highly rewarding when incorporated into a well-designed management plan.
Why Earlier Intervention Matters
One of the most significant shifts in modern sports medicine is moving treatment earlier in the disease process.
Rather than waiting for severe radiographic changes to develop, many veterinarians now focus on identifying:
- Early synovitis
- Capsular thickening
- Recurrent low-grade pain
- Mild performance deficits
- Progressive changes in movement quality
This approach allows intervention while joint structures remain relatively healthy.
Because Arthramid® requires approximately 1-2 weeks for tissue integration, early treatment planning can fit well around competition schedules and rehabilitation programmes.
Long-Term Joint Health Rather Than Short-Term Pain Relief
For many years the question asked was:
“How do we get this horse comfortable for the next show?”
Increasingly, owners and veterinarians are asking a different question:
“How do we keep this horse performing comfortably for the next five years?”
This is a fundamentally different mindset.
A successful long-term strategy typically combines:
- Accurate diagnosis
- Appropriate farriery
- Structured exercise programmes
- Weight management
- Rehabilitation
- Ongoing veterinary monitoring
- Evidence-based joint therapies
For many clinicians, Arthramid® has become an important component of that broader strategy because it supports the health of the tissues that are central to long-term joint function.
