Arthritis in Older Horses: Nutrition for Joint Health

Why Arthritis Is So Common in Older Horses

Arthritis — or more accurately, osteoarthritis (OA) — is one of the most common reasons older horses slow down. It's a progressive, degenerative condition where the cartilage that cushions joints gradually wears away, leading to pain, stiffness, and reduced mobility.

By the time your horse reaches their late teens or twenties, some degree of joint degeneration is almost inevitable. Years of ridden work, turnout on hard ground, conformational quirks, and the simple passage of time all take their toll. While arthritis can't be cured, the good news is that nutrition plays a surprisingly powerful role in managing it — slowing progression, reducing inflammation, and helping your horse stay comfortable and mobile for longer.

This article explores the nutritional angle of arthritis management in older horses. We'll cover the key nutrients, the supplements that actually have evidence behind them, and how to structure your senior horse's diet to give their joints the best possible support.

Understanding What Happens in an Arthritic Joint

Before diving into nutrition, it helps to understand what's actually going on inside an arthritic joint.

Healthy joints are lined with smooth articular cartilage, cushioned by synovial fluid, and held together by ligaments and a joint capsule. In osteoarthritis, the cartilage begins to break down faster than the body can repair it. The synovial fluid becomes thinner and less effective as a lubricant. Inflammation sets in, causing pain and swelling. Over time, bony changes develop around the joint margins.

This process is driven by:

• Mechanical wear and tear from years of use
• Chronic low-grade inflammation that accelerates cartilage breakdown
• Oxidative stress — free radicals that damage joint tissues
• Reduced ability to synthesise cartilage components as the horse ages

Nutrition can target several of these drivers directly. That's why getting the diet right is such an important part of the overall management plan — alongside veterinary care, appropriate exercise, and good farriery.

The Foundation: Getting the Basic Diet Right

Body Condition Matters More Than You Think

One of the single most important nutritional strategies for arthritic horses is maintaining a healthy body weight. Every extra kilogram your horse carries increases the mechanical load on already compromised joints. Overweight horses with arthritis tend to be stiffer, less willing to move, and harder to manage.

Equally, older horses that become too thin may lose the muscle mass that supports and stabilises their joints, making the problem worse in a different way.

The goal is a body condition score of around 5 out of 9 — where ribs can be easily felt but not seen, and there's a gentle covering over the topline without excessive fat deposits.

Quality Forage First

Forage should remain the foundation of any senior horse's diet. Good-quality hay or haylage provides fibre for gut health, steady energy, and a range of minerals. For older horses with dental issues that struggle to chew long-stem forage, soaked hay cubes, chopped fibre, or high-fibre senior feeds can fill the gap.

The reason this matters for joints is simple: a healthy gut supports a healthy immune system, and a well-regulated immune system is less likely to drive excessive inflammation throughout the body — including in the joints.

Balanced Minerals and Vitamins

Many horse diets in the UK and Ireland are deficient in key trace minerals, especially when horses live primarily on forage and a simple feed. For joint health specifically, the following micronutrients deserve attention:

• Copper — essential for the formation of collagen and connective tissue, including cartilage
• Zinc — involved in cartilage metabolism and tissue repair
• Manganese — a cofactor for enzymes involved in cartilage and bone formation
• Selenium and Vitamin E — powerful antioxidants that help combat oxidative stress in joint tissues

If your horse isn't receiving a balanced feed at the recommended rate, a good-quality vitamin and mineral supplement or balancer is essential. This is an area where analysing your horse's diet can be incredibly valuable — it lets you identify specific gaps rather than guessing or over-supplementing.

Key Nutrients and Supplements for Joint Health

The equine supplement market is enormous, and joint supplements are one of the biggest categories. Not all of them are worth your money. Here's what the evidence actually says.

Glucosamine

Glucosamine is one of the building blocks of cartilage. It's the most widely used joint supplement in both human and equine medicine. The theory is straightforward: by providing extra glucosamine, you support the horse's ability to maintain and repair cartilage.

The evidence in horses is mixed but generally positive for glucosamine hydrochloride at adequate doses (typically around 10,000 mg per day for a 500 kg horse). It appears to have modest anti-inflammatory effects and may help slow cartilage degradation.

The key word here is adequate doses. Many off-the-shelf supplements contain glucosamine at levels well below what research suggests is effective. Always check the label.

Chondroitin Sulphate

Chondroitin is another natural component of cartilage that helps it retain water and resist compression. It's often combined with glucosamine in joint supplements. Research suggests it may have anti-inflammatory properties and help inhibit enzymes that break down cartilage.

As with glucosamine, dose matters. Look for products providing meaningful amounts — typically around 2,500–5,000 mg per day — rather than token inclusions.

Hyaluronic Acid (HA)

Hyaluronic acid is a major component of synovial fluid, the lubricant inside joints. Vets have long used injectable HA directly into joints, but oral HA supplements have gained popularity in recent years.

The evidence for oral HA in horses is still emerging, but some studies suggest it may help improve synovial fluid quality and reduce inflammation markers. It's generally considered safe and may be worth trying, particularly for horses with multiple affected joints where repeated injections aren't practical.

Omega-3 Fatty Acids

This is one of the most consistently supported nutritional interventions for managing inflammation — not just in joints, but throughout the body. Omega-3 fatty acids, particularly EPA and DHA, have well-documented anti-inflammatory effects.

Horses naturally consume very little omega-3 in their typical diet (fresh grass contains some, but hay has almost none). Supplementation can come from:

• Marine sources (fish oil, algae-derived oil) — these provide EPA and DHA directly and are the most potent options
• Flaxseed (linseed) — provides ALA, which the horse must convert to EPA and DHA. Conversion rates are limited, but flaxseed still offers benefits and is more palatable to most horses

For arthritic horses, omega-3 supplementation is one of the interventions with the strongest evidence base. A typical daily dose of ground flaxseed is around 100–200 g, or follow the manufacturer's guidelines for marine oil products.

MSM (Methylsulfonylmethane)

MSM is a sulphur-containing compound often included in joint supplements. Sulphur is a component of connective tissues, and MSM is thought to have anti-inflammatory and antioxidant properties.

The evidence in horses is limited but promising. It's widely used, generally safe, and relatively inexpensive. Typical doses range from 10,000–20,000 mg per day.

Turmeric and Curcumin

Turmeric has become enormously popular among horse owners. The active compound, curcumin, does have demonstrated anti-inflammatory effects in laboratory studies. However, curcumin is very poorly absorbed from the gut in its natural form.

If you want to use turmeric, look for products that include bioavailability enhancers (such as piperine from black pepper, or lipid-based formulations). Simply adding ground turmeric to the feed is unlikely to deliver meaningful levels of curcumin to the joints.

Vitamin C

Horses synthesise their own vitamin C, unlike humans. However, there's some evidence that older horses and those under physiological stress may not produce enough. Vitamin C is important for collagen synthesis and acts as an antioxidant. Supplementation at moderate levels (3,000–10,000 mg per day) is generally safe and may offer support for aging joints.

Anti-Inflammatory Dietary Strategies Beyond Supplements

Reduce Pro-Inflammatory Inputs

It's not just about adding beneficial nutrients — it's also about reducing dietary factors that may promote inflammation:

• Excess sugar and starch can contribute to systemic inflammation and weight gain. Avoid high-starch feeds for arthritic seniors unless they genuinely need the calories.
• Omega-6 to omega-3 imbalance — cereal-based feeds are high in omega-6 fatty acids, which can promote inflammation when not balanced by adequate omega-3 intake.
• Iron overload — many UK and Irish forage-based diets are excessively high in iron, which can increase oxidative stress. Avoid supplements containing added iron unless specifically recommended by a nutritionist.

Prioritise Fibre and Fat for Energy

If your arthritic senior needs additional calories, choose fibre-based and oil-based energy sources over cereals. Sugar beet, high-fibre cubes, and vegetable oil provide energy without the inflammatory spike associated with high-starch feeds. This approach also supports a more stable blood sugar, which benefits overall metabolic health — another common concern in older horses.

Putting It All Together: A Practical Approach

Managing arthritis nutritionally doesn't have to be complicated or ruinously expensive. Here's a practical framework:

1. Start with the basics — good-quality forage, a suitable senior feed or balancer to cover vitamin and mineral requirements, and a healthy body weight.

1. Add omega-3s — flaxseed or a marine oil supplement. This is probably the single most impactful dietary addition for an arthritic horse.

1. Consider a joint supplement — choose one with evidence-based ingredients at effective doses. Look for adequate levels of glucosamine, chondroitin, and/or MSM. Avoid products that list dozens of ingredients at undisclosed or tiny amounts.

1. Ensure antioxidant support — adequate vitamin E and selenium, plus consider vitamin C for older horses.

1. Minimise pro-inflammatory dietary factors — reduce excess starch, balance omega-6 to omega-3 ratios, and avoid unnecessary iron.

1. Monitor and adjust — arthritis is progressive. What works at 18 may need tweaking at 22. Regular body condition scoring and working with your vet will help you stay ahead of changes.

When Nutrition Isn't Enough

It's important to be honest: nutrition alone won't eliminate arthritis. It's one piece of the puzzle. Veterinary interventions — including anti-inflammatory medications, joint injections, and emerging therapies like PRP or IRAP — may be necessary alongside dietary management.

Appropriate exercise is also crucial. Gentle, consistent movement helps maintain joint mobility and muscle strength. Standing still in a stable 24 hours a day is one of the worst things for an arthritic horse.

The beauty of the nutritional approach is that it supports everything else. A well-nourished horse responds better to veterinary treatment, tolerates exercise more comfortably, and has a better quality of life overall.

Final Thoughts

Arthritis in older horses is a condition we can't cure, but we can absolutely influence how it progresses and how comfortable your horse remains. Nutrition is one of the most accessible and impactful tools you have as an owner.

By building a balanced, anti-inflammatory diet — rich in omega-3s, supported by key micronutrients, and free from unnecessary pro-inflammatory ingredients — you're giving your horse's joints the best possible nutritional environment to function in.

Every horse is different, and the ideal diet for your arthritic senior depends on their individual needs, forage quality, workload, and any other health conditions. If you're unsure where to start, analysing what you're currently feeding is the logical first step — it takes the guesswork out of the equation and helps you make targeted, evidence-based changes that genuinely help.