The hoof wall is the part of the hoof that is seen and is the outside covering of the hoof. The hoof wall is responsible for protecting the hoof from infections, keeping in moisture, keeping out fungus and bacteria from the hoof as well as preventing damage to the hoof. It is roughly the same as a human's fingernails, although it is much thicker and denser. The hoof wall may become brittle, soft or cracked and damaged, leading to complications in the interior components of the hoof that can be extremely painful and even potentially prevent the horse from being able to work or move.
The most serious conditions of hoof wall problems in horses involve cracks either in the heel area or the quarters, which are the sides of the hoof. Hoof wall problems can also be seen in the toe or front area of the hoof, but this is less common. Cracks can lead to hoof wall loss if the crack is deep or becomes infected. The bacteria or fungus can spread under the surface of the hoof, gradually separating the hoof wall from the interior layers of the hoof and stripping the hoof's natural protection.
The horn-like material that makes up the hoof wall has no blood vessels or nerves, so the hoof wall itself does not cause the horse pain, it is the inside coffin bone, sole and ligaments that will become painful if an infection is present. The hoof wall must be trimmed on a regular basis to keep the hoof shaped as well as prevent the possibility of the hoof splitting or cracking.
The biggest cause of non-bacterial hoof wall loss is due to drying out of the hoof wall. Naturally the hoof wall is covered by a material that prevents moisture from being lost through the hoof wall, but does allow moisture to penetrate the wall. When this natural coating wears off due to walking in abrasive materials such as sand or gravel, the hoof wall no longer prevents moisture loss. Just like dry fingernails, the hoof wall will then become brittle and crack, or may even have small or large jagged splinters that expose the sensitive area of the inside of the hoof to possible damage. Hoof paints or sealants can be used to protect the hoof wall from abrasion and prevent excessive drying.
Horses that are kept in constantly wet conditions can also have problems with hoof wall loss as the hoof becomes excessively soft, resulting in hoof rot and chipping when the horse is exercised. Although some moisture is required for hoof health, excessive moisture, in particular soiled bedding, can be very harmful to the hoof.
Horses that are moved from one climate to another can often have hoof wall loss problems, especially those that go from extremely wet to dry conditions or vice versa. Corrective shoeing and proper, routine hoof care is essential for all horses to ensure healthy hoof walls. Additional supplements in the feed, dry, clean bedding and moist and dry areas of the pasture are all required for horses or ponies that have a history of hoof wall problems including cracks or dry hooves.