Horses are prone to hoof cracks for various reasons. Cracks can lead to the hoof chipping away in certain areas.

Cracks can be a cosmetic problem that can be easily corrected, but sometimes, they indicate something more serious is happening within the hoof.

Cracks often form in the hoof wall in a vertical direction, following the hoof tubules. They often originate from the bottom hoof surface or, less commonly, the coronary band. At times, a hoof crack may run the entire length of the hoof wall.

Cracks can also run horizontally, but these are less common and often have a different cause than those running vertically.

Hoof cracks can involve just the outer hoof wall or can invade the underlying sensitive structures and laminae. [1] Depending on the severity, cracks may or may not cause lameness.

Hoof cracks are usually described by their location, length (partial or full), and the presence or absence of bleeding and/or infection. In many cases, the underlying hoof damage is considerably more extensive than what is seen from the outside. [2]

Hoof Anatomy

A horse’s outer hoof comprises three main parts: the wall, sole, and frog.

The hoof wall (seen when the horse is standing) can be divided into three parts: the toe (front), quarters (sides) and heel (back). The sole and frog are visible when the hoof is lifted.

The hoof wall is made of keratin, a tough protein with low moisture content. Keratin is very strong and also insensitive, similar to human fingernails.

Along with the sole and frog, the hoof wall bears the horse’s weight while protecting sensitive structures inside the hoof capsule.

One of the most important structures in the hoof is the laminae, finger-like tissue projections that help attach the hoof wall to the coffin bone. The laminae also help the hoof maintain its structural integrity despite tremendous forces exerted by the horse. [3]

Hoof Wall

The hoof wall consists of three distinct layers:

  1. The stratum externum, or periople, is the thin, outermost layer of the hoof wall
  2. The stratum medium, or tubular horn, makes up the middle and thickest layer of the hoof wall
  3. The stratum internum which arises from the lamellar epidermis and, when combined with the laminae, attaches the hoof wall to the coffin bone (distal phalanx) [3]

Normally, the hoof wall grows at a rate of about 3/8 inch per month. New layers of hoof wall are continuously produced just below the coronary band, where the skin and hoof wall meet. [4]

The hoof is directly affected by nutrition and hydration. Load, limb conformation, and foot care also affect hoof shape. [4]

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