A horse that comes out of the stable stiff, moves woodenly for the first few circuits, and moves smoothly again after a quarter hour — for many owners, that's the first sign of arthritis. It's one of the most common diagnoses in older horses and in sport horses with years of work in their legs. Arthritis can't be cured, but it can be managed well: with the right approach, many horses keep working for years at a level that suits them. This guide explains what arthritis is, how to recognize it, and what you can do about it in daily practice.
What Arthritis Is
Arthritis is wear and inflammation of the joint cartilage — the smooth layer that covers the bone ends in a joint and lets them move smoothly against each other. In arthritis, that cartilage becomes thinner and rougher, and the joint becomes irritated. The body sometimes responds to this with extra bone formation around the joint, which further limits mobility.
Cartilage barely repairs itself. What's gone doesn't come back — arthritis is therefore irreversible. That sounds bleak, but the condition is manageable: the goal of all management is to slow the process down, keep the inflammation calm, and keep the horse comfortable at work. There's a lot of room between "having arthritis" and "suffering from it," and that room is exactly what you as an owner can influence.
Bone Spavin: The Best-Known Form
Bone spavin is arthritis in the lower, low-motion joints of the hock — the large hinge joint in the hind leg. It's such a classic presentation that it got its own name; you still come across the term in studbook and inspection contexts.
Typical for bone spavin is that the symptoms often start with a wooden, short stride behind that improves after warming up. In advanced bone spavin, a hard bony swelling can become visible or palpable on the inside of the hock. A counterintuitive detail: because the affected small joints move little on their own, the joint can eventually partly fuse — and the symptoms can, in some cases, actually decrease as a result. How that plays out in an individual horse can't be predicted; that's the vet's territory.
The Signs
Arthritis rarely announces itself with acute, obvious lameness. The picture is gradual and variable, and that's exactly what makes it hard to recognize. Watch for these signs:
| Sign | What you see |
|---|---|
| Starting stiff, "working out of it" | Wooden for the first few minutes, noticeably smoother after warming up |
| Variable lameness | Nothing visible one day, irregular the next — often worse after a rest day or on hard ground |
| Increasing unevenness | What started as occasional stiffness gradually becomes more frequent and clearer |
| Swelling or bony enlargement | A filled or thickened joint, or a hard lump such as with bone spavin at the hock |
| Behavior change | Reluctance at turns, transitions, or girthing up; difficulty giving a leg for the farrier |
A horse that "works out of it" when warm may seem to have resolved the issue, but it hasn't: warming up only masks the problem. Variable or persistent unevenness is always a reason to have it looked at — the guide on lameness explains how to assess a lame horse and when to call the vet.
Who It Affects
Arthritis is primarily a condition of the older horse: the more years, the more wear. In horses in their twenties, some arthritis is more the rule than the exception, and it's one of the points covered in caring for a senior horse.
But age isn't the only route. Sport horses can develop arthritis at a younger age from years of loading the same joints — think of the hock in dressage work, the fetlocks in jumping. Previous injuries, joint inflammation, abnormal limb conformation, and excess weight also raise the risk. Arthritis in a ten-year-old horse is therefore not a rarity, and "he's still too young for that" is no reason to ignore the signs.
Diagnosis: Off to the Vet
You don't diagnose arthritis yourself. The vet starts with a lameness exam: watching the horse move on a straight line and on a circle, on hard and soft ground, usually supplemented with flexion tests — a joint is held flexed briefly, after which the horse trots off immediately and the reaction says something about where the pain is.
To confirm the suspicion and pinpoint the location, imaging follows; X-rays are the usual first step. Important to know: the images and the pain don't always match up. A horse with clear abnormalities on the X-ray can have little discomfort from it, and vice versa. That's why the overall picture counts — the owner's account, the examination, and the images together — and the interpretation is up to the vet.
Management: Movement Is Medicine
The core of arthritis management is simple to remember and hard to keep up: consistent movement, every day.
- Plenty of free movement. A joint with arthritis stiffens up from standing still. As much turnout or paddock time as possible is the basis; a horse that stands in its stall 23 hours a day starts every training session at a disadvantage.
- Long walking during warm-up. Taking plenty of time at the walk — longer than you would with a young, healthy horse — gives the joint the chance to warm up before you ask anything of it.
- Regularity over peak loading. Six days of light work is better than two hard training sessions and four days in the stall. Avoid peaks: deep or uneven ground, lots of tight turns on the affected side, sudden heavy work after rest.
- Weight management. Every extra kilo is carried by the horse on its joints. In a horse with arthritis, a healthy condition isn't a cosmetic matter but direct pain management.
- Footing and shoeing. Discuss with your farrier and vet whether adjusted trimming or shoeing can relieve the affected joint; correct alignment and a smooth breakover reduce loading with every stride.
- A pain and treatment plan with the vet. Which treatment makes sense — and whether a supplement adds anything — differs per horse and per joint; you work that out with your vet and evaluate it periodically. Self-medicating or simply increasing the workload "to ride through it" is not a plan.
A Realistic Outlook
Arthritis is a diagnosis to take seriously, not a reason to panic. With good management, many horses keep working for years — often at an adjusted level: from Z-level dressage (an advanced national class) down to easier tests, from jumping to trail rides, from sport to leisure riding. The art is to let the work move with what the horse can handle, instead of holding onto what it once could do. How you adjust a training build-up without stopping the horse's work altogether is covered in horse injury recovery and retraining.
There may come a moment when the conversation shifts. If, despite a good plan, the horse remains structurally in pain, shows discomfort even at rest, can no longer lie down and get up comfortably, or can only be kept working with ever-heavier medication — then stopping work first, and eventually the question of quality of life, becomes something to discuss. You have that conversation with your vet, based on the horse in front of you, not on an X-ray.
In Short
- Arthritis is wear and inflammation of the joint cartilage: irreversible, but manageable.
- Bone spavin is the best-known form — arthritis in the lower joints of the hock, often with a bony swelling on the inside.
- Typical signs: starting stiff and working out of it when warm, variable or slowly increasing lameness, swelling around a joint.
- It mainly affects older horses, but also sport horses through years of loading — the vet makes the diagnosis, with flexion tests and imaging.
- Movement is medicine: plenty of free movement, long walking during warm-up, regularity over peak loading, plus weight management and suitable shoeing.
- Many horses keep working at an adjusted level for years; if the horse remains in pain despite a good plan, stopping work becomes an option to discuss.
See also: Lameness in horses explained · Caring for a senior horse · Horse injury recovery and retraining · Jargon: lame · Level: Considering your own horse