Keratomas Explained: Managing Hoof Tumours in Horses

A keratoma is a benign tumour of the hoof that develops between the hoof wall and the underlying sensitive laminae. Keratoma in horses is uncommon, but because the hoof capsule is rigid, even a small growth can create pressure, recurring abscesses and persistent lameness. Left unmanaged, a keratoma can damage the coffin bone, disrupt horn production and keep a horse out of work for months. This guide explains what causes keratomas, how vets and farriers diagnose them, and what realistic treatment and recovery look like in a British yard.

What Is a Keratoma in Horses?

A keratoma is a mass of keratin-producing tissue that forms beneath the hoof wall, usually along the inner surface of the horn. Keratin is the same protein that makes up skin, hair and the outer layer of the hoof. When keratin cells proliferate abnormally within the hoof capsule, they form a slow-growing tumour that displaces the coffin bone and puts pressure on sensitive tissue.

Keratomas are non-cancerous. They do not spread, and they rarely affect more than one hoof at a time. What makes them clinically important is location: because the hoof cannot expand outwards, even a small mass creates enough internal pressure to cause pain, recurring infection and eventually bone remodelling on the coffin bone (the distal phalanx, or P3).

Causes and Risk Factors

The exact cause of a keratoma is not fully understood, but several contributing factors have been identified by equine veterinary researchers:

• Chronic irritation or trauma — repeated bruising, severe concussion or pressure from a poorly fitting shoe can stimulate abnormal keratin growth.
• Previous hoof infections — recurrent hoof abscesses or deep quittor can damage the laminar tissue in a way that predisposes it to keratoma formation.
• Seedy toe and white line disease — chronic disruption of the white line appears to be associated with some keratomas.
• Penetrating injuries — solar penetrations that involve the laminar tissue can, in rare cases, heal abnormally and form a keratoma.

Keratomas can affect any horse. There is no strong breed, age or sex predisposition, although older horses, heavier horses and those kept in wet conditions over long periods may be seen slightly more often in referral caseloads.

Types of Keratoma

Veterinary surgeons usually describe keratomas by shape and location within the hoof:

• Cylindrical keratomas: the most common form, growing vertically along the inside of the hoof wall between the coronary band and the sole.
• Spherical keratomas: rounded, discrete masses located anywhere within the hoof capsule, often near the toe.
• Pedunculated keratomas: attached to the laminar tissue on a narrow stalk; less common but easier to remove surgically.

Location affects treatment: a keratoma at the toe is often reachable with a hoof-wall resection, whereas a quarter or heel keratoma may require more involved surgery and a longer recovery.

Symptoms of a Keratoma

Because keratomas grow slowly, symptoms are often intermittent at first and tend to escalate as the mass enlarges. Classic signs include:

• Low-grade, chronic lameness that worsens on hard or uneven ground
• Recurring hoof abscesses that always track to the same point
• A visible bulge or distortion of the hoof wall, sometimes with a curved deviation of the horn tubules
• A widened or broken white line at the sole surface, often packed with crumbly horn
• Heat, sensitivity to hoof testers or a positive response to pressure at a specific spot on the hoof wall
• In long-standing cases, remodelling of the coffin bone visible on radiographs

If a horse has repeated abscesses tracking to the same area of the foot, keratoma should always be on the differential list alongside deep-seated infection, a nail-bind or a fractured coffin bone.

How Keratomas Are Diagnosed

Accurate diagnosis usually combines clinical examination with imaging. A thorough vet work-up might include the following:

1. Lameness examination — static and ridden assessment, use of hoof testers and flexion tests to localise the pain.
2. Distal limb nerve blocks — a palmar digital nerve block should abolish lameness caused by a keratoma in the front half of the foot.
3. Radiographs — X-rays of the foot often show a characteristic semicircular lytic (dark) area on the coffin bone where the keratoma has caused bone resorption.
4. MRI or CT imaging — advanced imaging at a referral hospital gives the clearest view of the keratoma’s size, shape and exact relationship to the coffin bone and laminae.
5. Histopathology — after surgical removal, laboratory examination of the tissue confirms the diagnosis and rules out rare tumours that can mimic a keratoma.

Early, accurate diagnosis matters. The longer a keratoma is present, the more likely it is to cause significant bone remodelling and the longer the rehabilitation will take.

Treatment Options

Surgical removal is the only reliable treatment for a confirmed keratoma. Conservative management with corrective shoeing and antibiotics might control symptoms for a while, but it does not resolve the underlying mass. Two main surgical approaches are used in equine referral practice:

Partial Hoof-Wall Resection

The surgeon removes a small, precisely mapped section of hoof wall over the keratoma, exposes the mass and excises it in one piece. This is typically done under standing sedation and regional anaesthesia. It is the most common technique for accessible cylindrical keratomas.

Complete Hoof-Wall Resection or Partial Hoof-Wall Ablation

For larger or quarter-based keratomas, a larger portion of hoof wall may need to be removed. This is usually done under general anaesthesia, requires meticulous haemostasis, and leaves a significant horn defect that must be managed carefully until new wall grows down.

Post-operatively, the site is packed and bandaged, systemic antibiotics and anti-inflammatories are given, and the foot is supported with a hospital plate or custom shoe that bridges the defect.

Recovery and Return to Work

Recovery from keratoma surgery is measured in months, not weeks, because the hoof wall grows down at roughly 6–10 mm per month. A realistic timeline looks like this:

• Weeks 0–4: strict box rest, daily bandage changes, close monitoring for infection. Most horses are comfortable within a few days.
• Weeks 4–12: controlled in-hand walking on a firm surface, farrier visits every 4–5 weeks, gradual weaning off the hospital plate.
• Months 3–6: ridden walk and trot work introduced as horn regrows and the wall becomes load-bearing. Follow-up radiographs check coffin-bone healing.
• Months 6–12: phased return to normal work once the foot has fully regrown and passes veterinary re-examination.

Some horses are back in full work within six months. Others, particularly those with large defects or significant bone remodelling, may take nine to twelve months. Honest owner expectations and a good working relationship between vet, farrier and rider are the single most important predictors of a successful outcome.

The Role of Farriery

Farriery is central, not ancillary, to keratoma management. The farrier works alongside the vet before, during and after surgery. Key tasks include:

• Preparing the foot before surgery with careful balancing and hoof-wall mapping.
• Fitting a hospital plate or bar shoe post-operatively to protect the defect and redistribute load.
• Dressing in the regrowing horn tubules at every shoeing to keep the wall straight as it grows down.
• Using glue-on shoes or composites if nails cannot safely be driven near the defect.

Many horses recovering from keratoma surgery need to stay in a supportive shoeing package for a full hoof-growth cycle (nine to twelve months) before returning to conventional shoeing.

Prognosis and Long-Term Outlook

The prognosis for horses that undergo complete surgical removal of a keratoma is generally good. Published equine veterinary literature suggests a recurrence rate of less than 10 per cent when the mass is removed cleanly and the foot is managed well during regrowth. Most horses return to their previous level of work, including show jumping, eventing and happy hacking.

Prognosis is worse when:

• the keratoma is very large at diagnosis,
• significant coffin-bone remodelling is already present,
• the horse has concurrent laminitis or chronic infection, or
• post-operative management is compromised by turnout that is too early or too wet.

Can Keratomas Be Prevented?

There is no proven way to prevent keratomas, but sensible hoof-care reduces the risk of the chronic irritation and infection that appear to predispose some horses:

• Use a skilled farrier on a regular hoof-care cycle of 5–8 weeks.
• Address hoof abscesses, white-line disease and seedy toe promptly and thoroughly.
• Manage turnout to avoid prolonged standing in wet, muddy conditions.
• Investigate any horse that has more than one abscess in the same foot within a season rather than treating each one as a new, unrelated event.
• Keep radiographs on file if a horse has had previous foot problems so that subtle changes can be tracked over time.

Frequently Asked Questions