'Reading' the equine hoof - DVM
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'Reading' the equine hoof
Close examination can reveal much about foot conditions and overall health


DVM360 MAGAZINE


Examining the hoof


Photo 4:Wall cracks in a sound horse's hoof.
Initial examination of the hoof capsule should include an evaluation of balance and confirmation. The hoof should be viewed, in relation to the rest of the leg, from the lateral, medial, dorsal, palmar and solar aspects.

Additionally, it should be evaluated in its relationship to the column of the leg by sighting down the carpas-cannon line when viewing from above. Imbalance or abnormalities in confirmation, such as off-set hooves (medially or laterally in relation to the position of the cannon), low heel height, upright phalangeal angles or other variations can result in imbalanced landing and loading forces that can shift and alter the growth and appearance of the hoof.

It is then important to determine if these changes are the result of genetic variations in the bony structure of the horse, to inconsistencies and irregularities in farrier care or to a combination of both.

Radiographs often are essential in determining just how a particular horse should land and load weight on its hooves and how best to trim and/or shoe that horse to maximize this correct motion.

Horses with brittle, uneven hooves, imbalanced growth rings or various types of hoof cracks may all be suffering from some form of mechanical imbalance. Horses that do not hold shoes, that tend to break off sections of hoof, that either do not grow foot or tend to wear off hoof unevenly, may all be in this imbalanced cate-gory as well.

Good farrier attention aided by radio-graphs is the best solution for these cases, and it must be stressed to clients that this is a long-term process and will require a number of trimmings to achieve.

Nutritional needs


Photo 5:Coronary-band separation in the hoof.
Imbalanced feet are perhaps the easiest situations to deal with. Nutritional imbalances leading to poor foot growth would be the next most likely set of problems to consider when "reading" hoof capsule information.

It has long been accepted that the horse needs, along with good baseline nutrition, adequate protein, biotin, calcium, magnesium, methionine, zinc, sulphur, choline and copper to produce optimum hoof.

The hoof is composed largely of protein, and horses with low protein levels in their diets will have brittle, thin hair and weak, slowly growing hooves.

Fortunately, most commercial diets and most good pasture environments provide adequate protein to healthy horses.

Numerous studies have shown that biotin supplementation increases the growth rate and the eventual hardness of horse hoof. Scanning electron microscopic images taken of hoof horn from horses with brittle feet revealed that biotin was not the entire story, however.

Dr. S. Kempson of the Royal (Dick) School of Veterinary Studies at the University of Edinburgh showed that two types of defects were observed in horses with brittle feet. The first showed a loss of structure and horn, which was remedied with biotin supplementation. The second showed poor attachment of the horn to underlying structures, which was not reversed with biotin supplementation and required calcium supplementation as well. Therefore, adequate calcium and biotin are both necessary.

Magnesium is closely associated with calcium metabolism, and low magnesium levels have been associated with some types of laminitis, so levels of this mineral nutrient should also be monitored.

Sulphur is important in hoof growth and is incorporated into specific amino acids such as methionine and cysteine. Zinc and copper also are needed for hoof growth and the interrelationships between all of these nutritional factors quickly become crucial.

Deficiencies of any of them will inhibit proper hoof growth, but excesses can be just as detrimental. Excess calcium inhibits the bioavailability of zinc. Excess methionine decreases the absorption of copper and zinc. Overall it is essential that a good balanced diet with appropriate levels of crucial horn growth nutrients is available for all horses that exhibit problems with their hooves.

Diseases and infection

Infectious and systemic diseases can cause changes in the equine hoof. Various bacterial and fungal organisms can attack the skin at the coronary band and cause inflammation, irritation and sections of scabs and crusts.

Lymphangitis (of bacterial, viral or toxic nature) can cause excessive swelling along the coronet leading to serum extravasation, lipping of the coronet over the hoof capsule and even to hoof separation.

Autoimmune skin diseases such as Pemphigus foliaceus can cause hair loss and swelling at the coronary bands with associated lameness. These cases can progress to bullous-type lesions along the coronet. Vesicular stomatitis, foot-and-mouth disease and other viral infections also can affect the coronary bands of horses, and clinicians should be ever vigilant for these unique but very serious problems.

Often a mild lameness and inflammation of the coronary bands are the first lesions seen, and an observant practitioner will spot these signs and recognize that hoof abnormalities often reflect systemic diseases.

Toxins can cause problems with hoof growth as well. Selenium toxi-city will cause horizontal ridges in the hoof wall along with cracking and even sloughing or separation along the coronet.

Many poisonous plants, such as milk vetch, woody asters and golden weed, can cause inflammation and possible instability of the coronet.

Chronic diseases in other organ systems may influence absorption and digestion of needed nutrients, blood flow and distribution of those nutrients and general hoof growth.

Age-old concept

As early as 400 B.C., Hippocrates taught that nails reflected the inner body. Abnormalities of the nails, he believed, often could provide clues to common medical problems or severe systemic diseases.

This concept remains true for horses and humans today.

Because most horses, however, have darkly pigmented hooves, veterinarians cannot detect the subtle color changes and inclusion bodies that provide human physicians with additional information from nails.

Nonetheless, there are many important pieces of information available to clinicians who look at horses' feet and learn to read the tales of growth, balance, nutrition and the medical history written on the hoof.

Marcella is an equine practitioner in Canton, Ga.


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Source: DVM360 MAGAZINE,
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