Equine Guide
Horse Arthritis Signs & Treatment
An estimated 60% of lameness in mature horses is caused by osteoarthritis. Early recognition and a structured treatment approach can keep your horse comfortable and performing for years longer.
Understanding Arthritis in Horses
Osteoarthritis (OA) is the progressive deterioration of articular cartilage — the smooth, glistening surface that allows bones to glide against each other. In a healthy horse, this cartilage is remarkably durable, withstanding forces of up to 3 times the horse's body weight during galloping. But cartilage has no blood supply and very limited ability to repair itself. Once damage begins, it tends to progress.
The causes are varied: repetitive athletic stress, conformational faults (such as offset knees or long toes), acute injury (chip fractures, ligament damage), or simply the cumulative wear of age. Most horses over 15 will have some degree of arthritis detectable on X-ray, whether or not they show clinical signs.
The good news is that arthritis in horses is highly manageable. Unlike some conditions, there is a well-established ladder of treatment options that can be escalated as needed, from simple supplementation through to advanced regenerative therapies. The key is early recognition — the sooner treatment begins, the more cartilage can be preserved.
Commonly Affected Joints
Different joints are affected depending on the horse's age, conformation, and discipline. Understanding the anatomy helps you recognise early signs.
Hock (Tarsus)
Most common (~35% of equine arthritis)A complex joint with multiple small bones stacked between the tibia and cannon bone. The lower hock joints (distal intertarsal and tarsometatarsal) are most commonly affected because they bear compressive forces with minimal movement.
Signs to Watch For
- ●Short, choppy stride behind
- ●Reluctance to engage hindquarters
- ●Stiffness that improves with warm-up
- ●Swelling on the inner lower hock (bone spavin)
Most Affected Disciplines
Dressage, show jumping, stock horses
Fetlock (Metacarpophalangeal)
~25% of equine arthritisThe high-motion joint between the cannon bone and the long pastern bone. It absorbs enormous forces during galloping and landing from jumps — up to 2.5 times the horse's body weight.
Signs to Watch For
- ●Heat and swelling around the fetlock
- ●Shortened stride, especially at trot
- ●Reluctance to work on hard ground
- ●Windgalls that become firm rather than soft
Most Affected Disciplines
Racing, eventing, polo
Coffin (Distal Interphalangeal)
~20% of equine arthritisLocated entirely within the hoof capsule, this joint is invisible to external examination. Arthritis here is often missed until advanced because there is no visible swelling. The navicular bone sits adjacent and is frequently involved.
Signs to Watch For
- ●Subtle forelimb lameness, often intermittent
- ●Shortened stride that owners mistake for laziness
- ●Positive response to palmar digital nerve block
- ●Changes visible only on X-ray or MRI
Most Affected Disciplines
All — especially on hard surfaces
Stifle (Femorotibial/Femoropatellar)
~15% of equine arthritisThe largest and most complex joint in the horse, equivalent to the human knee. It contains two menisci, multiple ligaments, and three compartments. Stifle arthritis is particularly debilitating because the joint is critical for hindlimb propulsion.
Signs to Watch For
- ●Reluctance to canter or work uphill
- ●Dragging a hind toe
- ●Locking (upward fixation of the patella)
- ●Visible muscle wasting in the hindquarter
Most Affected Disciplines
Dressage, jumping, racing
Early Signs vs Advanced Disease
Early Signs — Act Now
- ●Stiffness that resolves within the first 5-10 minutes of work
- ●Reduced willingness to perform — not refusing, just less enthusiastic
- ●Subtle gait change detectable only by an experienced rider
- ●Performance plateau or slight regression without obvious cause
- ●Increased time to warm up, especially in cold weather
- ●Mild response to flexion tests performed by your vet
Advanced Signs — Urgent Veterinary Attention
- ●Obvious lameness at walk or trot, especially on hard ground
- ●Visible joint swelling, heat, or bony enlargement
- ●Significant loss of range of motion
- ●Reluctance to stand after lying down
- ●Weight loss from chronic pain reducing appetite
- ●Behavioural changes: irritability, ear pinning when saddled
- ●Compensatory lameness in other limbs
Diagnostic Methods
Flexion Tests
The vet holds the limb in a flexed position for 60 seconds, then the horse is immediately trotted away. Increased lameness after flexion indicates joint pain. A first-line screening tool performed at most lameness examinations.
Nerve & Joint Blocks
Local anaesthetic is injected around specific nerves or directly into a joint. If lameness improves, the source of pain has been localised. This is the most reliable way to identify which joint is causing the problem.
Radiography (X-rays)
X-rays reveal bony changes associated with arthritis: osteophytes (bone spurs), joint space narrowing, subchondral bone sclerosis, and periarticular new bone. Multiple views are required for each joint.
Ultrasound, MRI & CT
Ultrasound assesses soft tissue (ligaments, joint capsule). MRI provides superior detail of cartilage and bone, especially for coffin joint and navicular disease. CT is useful for complex joints like the hock and stifle.
The Treatment Ladder
Equine arthritis treatment follows a step-wise approach. Start at the bottom and escalate as needed. Most horses are well-managed at levels 1-4.
Exercise & Environment Modification
Adjust workload to the horse's comfort level. Maintain regular low-impact exercise (walking, gentle trotting) to preserve joint mobility and muscle mass. Provide soft footing in paddocks and stables. Avoid deep or uneven ground.
When: First approach for all stages. Continue alongside all other treatments.
Joint Supplementation
Green-lipped mussel powder (Joint Rejuvenate) mixed into hard feed daily. Provides anti-inflammatory omega-3s (including ETA), glucosamine, chondroitin, and hyaluronic acid. No withholding period for competition. Safe for indefinite daily use.
When: Start at first signs. Continue as lifelong maintenance.
Oral NSAIDs
Phenylbutazone (bute) or meloxicam for pain management during flare-ups. Effective but carries risks of gastric ulceration and kidney effects with long-term use. Use at the lowest effective dose for the shortest duration.
When: Flare-ups, competition preparation, or moderate daily pain.
Pentosan Polysulphate Injections
A course of 4 intramuscular injections at weekly intervals. Pentosan is a disease-modifying agent that stimulates cartilage repair and inhibits destructive enzymes. Synergistic with green-lipped mussel supplementation. Repeat courses every 6-12 months.
When: Confirmed arthritis with cartilage changes visible on X-ray.
Intra-Articular Injections
Corticosteroids (triamcinolone) or hyaluronic acid injected directly into the affected joint under ultrasound guidance. Provides potent localised anti-inflammatory effect. Repeat no more than 2-3 times per year per joint.
When: Moderate to severe joint inflammation not controlled by oral treatment.
Regenerative Therapies
Platelet-rich plasma (PRP), interleukin-1 receptor antagonist protein (IRAP), or stem cell therapy. These advanced treatments use the horse's own blood or cells to promote healing. Expensive but showing promising results in clinical trials.
When: Performance horses with moderate arthritis. High cost justified by competition value.
Surgical Intervention
Arthroscopic debridement to remove loose fragments, or chemical arthrodesis (joint fusion) for low-motion joints like the lower hock. Joint fusion sounds dramatic but is well-tolerated in the distal hock joints because they have minimal natural movement.
When: End-stage disease in specific joints. Arthrodesis for hock spavin.
Joint Rejuvenate Dosing for Horses
Joint Rejuvenate is the same freeze-dried, whole green-lipped mussel powder used for dogs and cats, but dosed appropriately for the horse's larger body weight. Mix the powder into hard feed — most horses accept it readily due to its mild, slightly fishy flavour.
| Purpose | Dose Rate | 500kg Horse | Duration |
|---|---|---|---|
| Prevention / Maintenance | 2mg/kg | 1g/day | Ongoing |
| Early Arthritis | 6-10mg/kg | 3-5g/day | Ongoing |
| Active Treatment | 20mg/kg | 10g/day | 8-12 weeks, then reduce |
| With Pentosan Course | 20mg/kg | 10g/day | Start 1 week before pentosan, continue 12 weeks |
Competition note: Green-lipped mussel is a natural food product with no prohibited substances under FEI, Racing Australia, or Equestrian Australia rules. There is no withholding period before competition. Always check current prohibited substance lists for your specific discipline.
Managing Retired Horses with Arthritis
Retirement from work does not mean retirement from arthritis management. In fact, retired horses are at increased risk of joint stiffness because reduced exercise leads to loss of muscle mass and joint mobility. A horse that stands in a paddock all day without structured movement will often deteriorate faster than one in light work.
The ideal retirement management plan includes daily turnout on good footing (avoid mud and boggy paddocks), a companion for social stimulation and natural movement, continued daily supplementation with Joint Rejuvenate at the maintenance dose, and regular hoof care — even non-working horses need balanced feet to distribute weight evenly across arthritic joints.
Many owners of retired performance horses find that continuing very light ridden or in-hand work (10-15 minutes of walking and gentle trotting several times a week) keeps the horse more comfortable than complete rest. The key is consistency — a little movement every day is far better than occasional longer sessions.
Protect Your Horse's Joints
Joint Rejuvenate for Horses is available in 100g to 3Kg sizes. Free equine consultation with Dr John Stewart included.