Although not a disease, shelly feet mark the existence of a serious defect in the secreting properties of the horn-producing structures of the foot. Large numbers of otherwise valuable animals are rendered troublesome and sometimes practically worthless in consequence of a want of adequate protection and indifferent quality of the horn composing the hoof; the coarseness and brittleness of its fibres and looseness of its texture rendering it apt to break away on the slightest provocation, and to afford the shoe a most insecure attachment to the foot. Shelly feet are necessarily weak feet. The crust in these cases is usually thin, the heels are low, the feet flat and spreading, and the soles lack both substance and strength. They are besides hot, dry, and brittle, frequently marked by ridges and furrows, indicating irregularity in secretion, and in consequence of these conditions the crust readily breaks away as the result of "nailing".
In the great majority of cases of this kind, heredity is the chief predisposing factor. Some horses at a very early age, and before being stabled, manifest a decided brittleness of hoof-horn, which is seriously aggravated when the forces of domestication come into play. Of these, the undue allowance of highly stimulating food in the absence of adequate work is a common exciting cause; as is also excessive burning in the fitting of shoes, and the impairment of the circulation of the foot resulting from undue paring of the frog and its removal from the ground.
A shelly condition of the foot sometimes dates from an attack of influenza, fever, or some other febrile ailment, and it invariably follows in a higher or lower degree on all attacks of fever in the feet (laminitis).
Where this condition exists, the most salutary effect may be obtained from a run at grass in a damp meadow and a course of stimulating applications to the coronets. If the weather is dry and the pastures parched, little or no benefit will result from turning out in the daytime. In these circumstances a run in a wet yard by day and in the pasture by night will afford the best results. As an application to the hoof, glycerine, worked up with a little fish-oil and tar, will be found useful while the animal is in the stable. In shoeing, as little heat as possible should be applied to the crust, and the frog should be allowed to grow and come to the ground. Beans, maize, and barley are undesirable additions to the food where a tendency exists to brittleness of the hoofs.