Sesamoiditis in Horses: Causes, Treatment & Recovery

A warm, slightly puffy fetlock after fast work, and a horse that's a touch short on the flexion test. It's easy to put it down to a hard session, but the cause is often one of the smallest bones in the leg. Sesamoiditis in horses is inflammation of the sesamoid bones and the ligaments that anchor to them, and it's one of the most common sesamoid bone problems in racehorses and performance horses.

Caught early and managed with your vet, many horses recover well. Left alone, it can lead to ligament injury or a sesamoid fracture.

Quick Answer

• What it is: inflammation of the proximal sesamoid bones at the back of the fetlock, usually from repeated stress at speed.
• What to look for: heat and swelling behind the fetlock, lameness, and pain when the fetlock is flexed.
• How it's confirmed: your vet will use a lameness exam, X-rays and ultrasound. Never guess at this one.
• How it's managed: rest, cold therapy, support bandaging, vet-prescribed anti-inflammatories, farrier input and a slow, staged return to work.
• Outlook: many horses return to work, but timing and results depend on how much ligament damage is present.

Where Is the Sesamoid Bone in a Horse?

Every horse has two proximal sesamoid bones on the back of each fetlock joint. They sit like a pulley behind the joint and are held in place by branches of the suspensory ligament above and the sesamoidean ligaments below.

Together, these structures form the suspensory apparatus. It supports the fetlock and stops it from dropping too far under the horse's weight. At a gallop, that load is huge, which is why a sesamoid bone horse injury shows up so often in racing and other fast work.

What Is Sesamoiditis in Horses?

Sesamoiditis is inflammation of the sesamoid bones and where the ligaments attach to them. The abaxial (outer) edge of the proximal sesamoid bones is vulnerable to stress-related injury during fast exercise.

You'll see it most in young racehorses, hunters, jumpers and barrel horses. And because the signs look a lot like a sesamoid fracture, only imaging can tell them apart.

What Causes Sesamoiditis in Horses?

No single cause explains every case. Repeated high-speed or jumping work puts strain on the bone where the ligaments pull on it. Add a few risk factors and that strain builds faster:

• Conformation: long pasterns and low heels. A 2024 study of racehorses with sesamoiditis found low-heeled hoof structure played a role in many cases.
• Unbalanced feet: a poor hoof angle changes how load travels through the fetlock.
• Training load: big jumps in work, hard surfaces and tight turns.
• Extra weight: more body weight means more load on the suspensory apparatus.

Signs of Sesamoiditis in Horses

Look for these around the back of the fetlock:

• Heat and mild swelling
• Lameness, often worse after fast or heavy work
• Pain when the vet squeezes the sesamoids or flexes the joint
• A drop in performance, or a horse that's "just not right"

How Is It Diagnosed?

Your vet starts with a lameness exam, then X-rays of the fetlock. Changes can include enlarged vascular channels, bone spurs and areas of bone loss. Ultrasound assesses the suspensory ligament branches, which are often involved as well.

The MSD Manual reports that when significant sesamoiditis shows on X-rays, horses had a five times greater risk of suspensory ligament branch injury once training began. Early imaging protects both the ligaments and the bone.

What About a Sesamoid Fracture in a Horse?

A sesamoid fracture in a horse is the more serious cousin of sesamoiditis. Fractures are classed by where they sit on the bone: apical, mid-body, basilar and abaxial. Apical fractures are the most common in Thoroughbreds and Standardbreds, and signs include heat, pain and sudden lameness that worsens when the fetlock is flexed.

Treatment often means surgery. A 2025 study of Thoroughbred racehorses found 42.3% of horses with forelimb fractures returned to racing, compared with 65.6% with hindlimb fractures. If both sesamoids break, the injury is catastrophic. That's why any sudden or worsening lameness at the fetlock needs a vet straight away.

Treatment for Sesamoiditis in Horses

Treatment is built around your vet's diagnosis. For most horses, it includes:

• Rest. Box rest or restricted exercise until your vet is happy with soundness and repeat imaging.
• Cold therapy. Cooling the fetlock after work or during flare-ups helps settle heat. Ice boots for horses make this easy and consistent.
• Support bandaging. Quality horse bandages support the limb while it settles. Ask your vet how to wrap correctly, because poor bandaging causes its own problems.
• Topical gel. Many owners use a cooling gel such as Rapigel for horses under a bandage as part of the vet's plan.
• Anti-inflammatories. Prescribed by your vet, based on your horse.
• Joint support. Some owners add horse joint supplements to their horse's routine. Check the choice with your vet first.
• Farrier changes. Ask your farrier about hoof balance and heel support. Low heels are a known risk factor, so correcting them can reduce strain.

Can a Horse Recover From a Sesamoid Injury?

Yes, many do. Sesamoiditis can have a positive prognosis with appropriate treatment and adequate rest, especially when treatment starts early.

The outlook gets less certain when the suspensory ligament is also damaged, or the injury is a fracture. Your vet can give you the best read for your horse.

How Long Is Recovery?

Plan in months, not weeks. There's no fixed timeline, because it depends on how much bone and ligament are affected. Your vet will set it using repeat exams and imaging.

A typical return to work is staged:

• Rest until your vet confirms soundness
• Walking in hand, then under saddle
• Gradual trot work on good, even footing
• Slow increases toward fast work or jumping

Rushing this stage is the usual reason horses re-injure. Stick to your vet's plan, even when your horse feels sound.

Support Your Horse's Recovery With Scone Equine

Scone Equine Group is Australia's largest equine veterinary group, and our online store stocks vet-grade products you can trust at reliable prices. Whether you need ice boots, bandages or gels for rehab, you'll find them in one place. Shop vet supplies for horses or ask our team for advice.

Always check with your vet before starting treatment. This article is general guidance and doesn't replace a diagnosis for your horse.