What the Muck Is That? ‘Keratoma’

Each week we investigate one equestrian conundrum in “What the muck is that?” This week we take a look at keratomas by reader request.

We recently received this message from a reader:


So… what the muck is that?

A keratoma is a rare benign tumor that forms inside a horse’s foot. As the tumor slowly grows, it expands and separates the hoof wall laminae, causing pain and lameness.


Source: Sun Forge

Two forms of keratoma are recognized:

  • ‘Cylindrical’-shaped keratomas, which run in the hoof wall directly towards the sole.
  • More discrete ‘spherical’-shaped keratomas, most often towards the toe.

What causes a keratoma?

The cause of this cancer is unknown. Some cases follow an injury to the coronary band, but many do not. The tumors are benign and never spread to other areas of the horse’s body.

What are the symptoms?

  • Bulging hoof wall at the coronet — may or may not have pus
  • Slow, progressive lameness
  • White line distortion towards the frog because it’s being pushed behind the tumor


Source: Chest of Books

How is it diagnosed?

  • X-rays
  • Histological examination — taking a tissue sample, staining it, and studying it under a light microscope


Source: Keenan McAlister

How can it be treated?

The tumor and overlying hoof wall requires surgical removal under local or general anesthesia. The hoof is often fitted with a hospital plate to keep the wound clean and dry. Antibiotics are often prescribed as well.


Source: Vet Book

What’s the outcome?

Growing hoof wall is a slow process (estimate 0.6 cm per month), but if the owner takes care to keep the wound clean the prognosis to return to work is good.

Go Riding!

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