The same state of affairs may be occasioned in the forge by leaving one side of the foot too high, and subjecting the other to excessive paring for several consecutive shoeings.

Treatment.—­In the main this condition may be regarded as a long-standing and aggravated form of the foot with unequal sides.  We may say at once, therefore, that it is not so easily remedied as that simpler defect; that, although identical principles will be followed in its treatment, cure must be a matter of some considerable time.

[Illustration:  FIG. 85.—­SECTION THROUGH A CROOKED FOOT. a, The higher and convex side of the wall; b, the lower and concave side of the wall]

Again, we must look to successive parings of the wall of the higher side to bring about a gradual return to the normal.  At the same time, the tendency to contraction of that side is counteracted by shoeing wide, and, if necessary, giving to the upper surface of that branch of the shoe what we have termed elsewhere a ’reversed seating’—­viz., an incline of its upper surface from within outwards.

CHAPTER VII

DISEASES ARISING FROM FAULTY CONFORMATION

A. SAND-CRACK.

Definition.—­A solution of continuity of the horn of the foot, occurring usually in the wall, and following the direction of the horn fibres.

Classification.—­It is usual to classify sand-cracks according to—­

(a) Their Position.—­Toe-crack when occurring in the middle line of the horn of the toe, and quarter-crack when occurring in the horn of the quarters.

Sand-crack of the frog and sand-crack of the sole may also each be met with.  They are, however, of rare occurrence, and are seldom serious enough to merit special attention.

The toe-crack is met with more often in the hind-foot than in the fore, while the quarter-crack more often than not makes its appearance in the fore-foot, and is there, as a rule, confined to the inner side.  The reasons for these positions being so affected we shall deal with when treating of the causes of sand-crack in general.  It is interesting to note that the portions of wall known as inside and outside toe are seldom affected.

(b) Their Length.—­Complete when they extend from the coronary margin of the wall to its wearing edge; Incomplete when not so extensive.

(c) Their Severity.—­Simple when they occur in the horn only, and do not implicate the sensitive structures beneath; Complicated when deep enough to allow of laceration and subsequent inflammation of the keratogenous membrane.  Such complications may vary from a simple inflammation set up by laceration and irritation of the sensitive structures by particles of dirt and grit that have gained entrance through the crack, to other and more serious changes in the shape of the formation of pus, haemorrhage from the laminal vessels, caries of the os pedis, or the development of a tumour-like growth of horn on the inner surface of the wall known as a keraphyllocele.