An article by William Schurg P.H.D. Department of Animal Sciences, University of Arizona.
Related Links:
Back to Horse Health Articles page
Submit a Horse Health Article
The hoof is a highly modified form of specialized skin. It consists of two layers, the outer layer called the epidermis and the inner layer called the dermis or in the horse hoof, the corium. The epidermis contains no blood vessels of its own and derives oxygen and nutrients from the blood supply in the corium of the foot. The hardness of the horse foot is derived from a fibrous protein material called keratin. This is the same substance which makes of the human fingernails.
The rate of and quality of growth of equine hooves vary just like our finger and toe nails vary in growth. The hoof wall (hard outer layer of the foot) in the normal adult horse grows at a rate of about an eighth to a quarter of an inch each month. It takes about 9-12 months for the hoof to grow from the coronet to the ground surface while the quarters and heels grow more rapidly. Since the distance from the coronet to the ground is shorter at the heels than at the toe, heel hoof horn is younger than toe horn and will generally be more moist and have greater elasticity.
Young horses have considerably faster foot growth than adults. A nursing foal can grow foot at a rate of nearly 0.6 inches per month and will slow growth to about 0.5 inches per month as it approaches a year of age. Besides youthfulness other factors which will influence the rate of hoof growth are: external temperatures (cold weather slows growth while spring weather accelerates growth); environmental moisture (dry conditions tend to retard growth while wet weather stimulates foot growth); genetics (some breeds of horses like Arabians are known for the quality and denseness of their hoof walls); illness and fever (high body temperatures may retard or deform hoof growth resulting in fever rings on hooves months after the illness); injury to the coronary band creates reduction in the generative tissues and thus retardation of hoof growth; weight-bearing on other feet (a lameness in one leg causes the horse to compensate to effectively move, thus increasing or decreasing degree of wear of the hoof wall); exercise (as exercise increases, metabolism speeds up and accelerates hoof growth); nutrition (recently several dietary elements must be replaced daily in order for optimal hoof growth to occur).
As one can see many factors influence hoof growth. Good management decisions regarding nutritional support, hoof care and exercise are all things within the horse owners control. It is well known that an under-nourished horse can have an adverse effect on hoof growth as well as other health related considerations. Nutrients can also have an impact on hoof growth. Maintenance of adequate levels of protein (especially essential amino acids) is important. The need for minerals like calcium and the relationship to phosphorus is critical for horse hoof integrity. In recent years, a B vitamin called biotin has been shown to influence hoof wall growth and integrity and has no known side effects from supplementation.
Researchers still can not pinpoint why some horses respond to biotin supplementation while others do not, but if your horse has thin, brittle hoof walls with tender soles biotin appears to work for those individuals. The use of amino acid supplementation (i.e., methionine); fats and oils in the diet as well as supplemental zinc and copper all have shown various improvements in both growth rate and integrity of hoof quality. The bottom line is that horse owners should understand the importance of good feet under their horses. Use of common sense, a little science and art of feeding, exercise and farriery management all will aid in creating and maintaining a sound equine companion.
Reprinted with permission: University of Arizona Dept of Animal Sciences October 2002.
