Arthritis is the single most common reason a performance horse slows down, stiffens up, or gradually stops being the horse you knew. It is also one of the most misunderstood. Owners are often told their horse “just has a bit of arthritis”, as though that is the end rather than the beginning of a conversation. In reality, how you respond in the first months after diagnosis can shape whether a horse keeps competing for years or steps down early.
This guide explains what arthritis actually is, how it is diagnosed, and the full spectrum of treatment options available in New Zealand today, including two regenerative therapies that were not available in NZ until recently.
What is arthritis?
The proper term is osteoarthritis, and it describes disease of a joint rather than a single injury. A healthy joint is a remarkable piece of engineering: two bone ends capped with smooth cartilage, bathed in joint fluid (synovial fluid) that both lubricates and nourishes, all wrapped in a capsule lined by a membrane (the synovium) that produces that fluid.
Osteoarthritis is what happens when this system enters a cycle of damage and inflammation. Cartilage begins to wear or is injured, the synovium becomes inflamed, and the inflamed joint releases enzymes and inflammatory proteins that damage the cartilage further. That damage drives more inflammation, which drives more damage, leading to a viscous cycle of degradation.
Two points matter here. First, arthritis is progressive, which is why early, active management outperforms waiting. Second, much of the pain and ongoing damage is driven by inflammation, which is precisely why the newer treatments aim to interrupt the inflammatory cycle rather than simply mask the soreness.
What causes it in horses?
Arthritis in horses usually comes from one of a few routes. Wear and tear from athletic work is the classic cause, especially in joints that take high loads, such as the fetlocks, hocks and knees. Or a single injury can trigger it: a sprain, a joint infection, or a fragment of bone or cartilage (sometimes from an old developmental problem) sitting where it should not. Poor conformation can also load certain joints unevenly and wear them faster. Age plays a part, though arthritis is by no means limited to older horses. Many performance horses develop it in their working prime.
The signs you actually notice
Textbook lameness is the obvious sign, but it is rarely the first one. Horses are stoic, and the early signs of arthritis are usually subtle changes in how a horse feels rather than dramatic lameness. Owners often describe: stiffness that wears off with work, especially first thing or in cold weather; a reluctance to work on one rein, or to strike off on a particular canter lead; a horse that has become “grumpy,” resistant, or simply flat; shortened stride or a loss of the swing and expression that used to be there; occasional heat or filling in a joint; and a slow decline in performance that does not fit any single event.
The phrase I hear most often is some version of “he just isn’t himself.” That is a presenting complaint worth taking seriously. Owners know their horses, and “not quite right” is frequently the earliest honest description of a joint that is becoming sore.
How arthritis is diagnosed
A diagnosis of arthritis is built in stages, and each stage narrows down the question.
The examination comes first. A thorough lameness evaluation looks at the horse standing and moving, on hard and soft surfaces, in straight lines and on the lunge. Flexion tests, where a joint is held flexed for a period and the horse then trotted off, help point to the region involved. Palpation identifies heat, swelling, and pain, or reduced range of motion.
Diagnostic analgesia (nerve and joint blocks) is often the next step. By temporarily numbing a specific joint or region and watching whether the lameness improves, we can confirm exactly where the pain is coming from. This matters, because a horse can have visible changes on an X-ray in a joint that is not actually the source of the lameness, and the reverse is also true.
Imaging then shows the structure. Radiographs (X-rays) reveal bony changes such as new bone formation and narrowing of the joint space. Ultrasound assesses the soft tissues, cartilage and bone around the joint. In selected cases, advanced imaging, such as CT, adds further detail. It is worth understanding that early arthritis can be painful before it is obvious on an X-ray, so a “clean” radiograph does not always mean a comfortable joint. This is one reason the examination and the blocks carry so much weight.
The treatment options
There is no single treatment for arthritis. There is a spectrum of options, and where a horse sits in that spectrum depends on the joint involved, the severity, the horse’s job, and how the joint responds. A sensible plan usually combines several approaches rather than relying on one.
Foundation: management, weight and exercise
Before any injection or medication, the basics really do work. Appropriate, consistent exercise keeps joints mobile and supports the surrounding muscle; complete rest is rarely the answer for a chronically arthritic joint. Keeping a horse at a healthy weight reduces the load on every joint. Mobility and strengthening work, often in conjunction with a physio or rehab specialist, is essential to maintain long-term comfort. Good hoof care and balanced trimming or shoeing change how forces travel through the limb. Sensible surfaces and a thoughtful warm-up round out the foundation. None of this is an easy quick fix but it all matters.
Systemic joint therapies
Medications given by injection into muscle or vein, rather than into the joint, aim to support joint health more broadly. Pentosan/Cartrophen (pentosan polysulphate), 4cyte (Epitalis), Adequan (PSGAG) and Matrix (hyaluronic acid) sit in this group. The evidence base varies between products, and they are often used as part of a maintenance programme rather than as a sole treatment.
Intra-articular medication
Injecting medication directly into the affected joint delivers treatment directly where it is needed. Intra-articular treatment is a mainstay of managing the performance horse, and the choice of medication, dose and frequency is a veterinary decision tailored to the joint and the horse.
Corticosteroids are potent anti-inflammatories, relatively cheap and, used appropriately, can give excellent relief and settle an inflamed joint. Arthramid is a polyacrimade hydrogel and another non-steroid intra-articular option. It gets incorporated into the joint lining and acts to make the joint fluid healthier and reduce anti-inflammatory proteins. Case selection is important as it may not be the most effective option, particularly in larger joints.
Regenerative and biological therapies
This is the rung that has changed most, and it is where New Zealand horses now have options they did not have until recently. Rather than only suppressing inflammation, these therapies use the horse’s own biology to modify the disease process itself. They include ProStride APS and Alpha2EQ (autologous conditioned serum), along with IRAP, stem cells and PRP.
Because these are the newest and least familiar options, I will focus on ProStride and Alpha2EQ:
Regenerative options, explained
The idea behind these therapies is to process the horse’s own blood and so put the horse’s own healing factors directly into the area they are most needed. Cartilage does not have a blood supply and joints are often poorly supplied by the horse’s own system. The inflammation that drives arthritis is orchestrated by specific signalling proteins, and the body also produces proteins that block those signals. By concentrating the blocking proteins and delivering them into the joint, you can interrupt the damaging inflammatory cycle using the horse’s own biology, with no foreign drug involved.
ProStride APS (autologous protein solution) takes a sample of the horse’s own blood and processes it, in a dual-centrifuge system, into a concentrated solution rich in anti-inflammatory proteins and growth factors. The most important of these is a natural blocker of interleukin-1, one of the key drivers of joint inflammation. The concentrated solution is injected into the affected joint. It is prepared horse-side and delivered in a single visit. We use this most in horses that require soft tissue healing and anti-inflammatory effects, e.g. stifle with meniscal injury, sacroiliac region pain with ligament injury.
Alpha2EQ (alpha-2-macroglobulin) works on a related principle, producing a serum from the horse’s own blood that is rich in potent anti-inflammatory proteins. We get a much larger volume (15-30mL) from A2EQ than Prostride, and it is most useful for treating arthritis in multiple joints and larger areas, like the SI region, for powerful anti-inflammatory and pain relieving effects.
The appeal of these therapies for the performance horse is fourfold: they use the horse’s own biology, they aim to modify the disease rather than only mask it, they avoid the withholding and regulatory considerations that come with some medications, and they do not have the risk to cartilage or the insulin spike (laminitis risk) that steroids do. However, they are not a magic cure, they are not right for every joint, and they sit within the ladder rather than replacing it. Used in the right case, they are a genuine advance and real game-changer.
We are currently the only practice in New Zealand offering ProStride and Alpha2EQ, and we deliver them ambulatorily, at your yard, or at our purpose-built performance and rehab clinic.
Anti-inflammatory medication
Non-steroidal anti-inflammatory drugs (NSAIDs) such as phenylbutazone (“bute”) and firocoxib (Previcox) reduce pain and inflammation. They are effective, affordable and widely used in later stage or multi-locational arthritis. For many horses, they are part of a long-term plan to stay paddock sound. Their limitation is that they treat the symptom rather than the joint, and long-term use warrants veterinary oversight due to the risk of side effects, such as gastric ulcers and kidney damage. They are a tool in the plan, not the whole plan.
Bisphosphonates
In advanced cases with uncontrolled bone pain, using bisphosphonates (Osphos, Tildren) off-label can help with pain relief. However, caution is advised and careful case selection recommended, as these drugs have some serious and long-term side effects. Due to their effects on bone turnover, they are contra-indicated in growing horses or horses in high intensity exercise, such as eventing and racing. For this reason, they are banned in FEI and many racing jurisdictions.
Surgery
For specific problems, such as a bone or cartilage fragment within a joint, arthroscopic surgery to remove the fragment can address the underlying cause. In advanced cases of arthritis in certain low-motion joints, like the lower hock joints or pasterns, surgical fusion (arthrodesis) can turn a painful joint into a stable, comfortable one. Surgery is referred to a hospital facility, and we coordinate that referral where it is the right answer.
Adjuntive therapies
Adjunctive therapies, such as shockwave, acupuncture, massage and PEMF, can be a useful addition to other treatment options to improve pain relief and maintain joint and whole body comfort.
What a good plan looks like
An effective arthritis plan is rarely just one therapy. For a typical competition horse with fetlock arthritis, it might combine sensible management and hoofcare as the foundation, an intra-articular treatment or a course of regenerative therapy to settle and modify the joint, a systemic maintenance therapy through the season, and an agreed review point to check the joint is responding. The specifics are chosen for the horse in front of you, which is the whole point of a tailored approach.
Two principles hold across almost every case. Earlier intervention gives more options and better outcomes than waiting until a horse is visibly lame. And the plan should be reviewed and adjusted, because arthritis changes over time and so should its management.
When to call a specialist
A specialist sports medicine opinion is most useful when you are struggling with gaining a clear diagnosis, when a horse has not responded to first-line treatment as expected, when advanced diagnostics would change the plan, or when you want access to the full range of regenerative options and a rehabilitation programme built around returning to performance. In every case, your own vet should remain part of the team.
The take home message
Arthritis is common, it is progressive, and it is more treatable than it has ever been. “A bit of arthritis” is not a verdict, it is the start of a management plan. If your horse has stiffened, lost its sparkle, or simply is not itself, then that is worth investigating early, while you have the most options open to you. If you would like a specialist assessment, or you want to talk through whether regenerative therapy is right for your horse, we would be glad to help.
Sports Med Vet provides specialist equine sports medicine and rehabilitation care across Canterbury and the wider South Island. We can come to you and also have a dedicated Canterbury clinic and rehab centre.
Call 02904500824 or book through http://www.sportsmedvet.co.nz.
Related reading: [ProStride APS: the evidence behind New Zealand’s newest joint therapy]; [Alpha2EQ and autologous conditioned serum: what owners should know]; [What happens during a specialist lameness examination].
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