unable to bear the strain.  They turn in, and contraction commences.  This ’turning in’ of the heels is favoured by the undue obliquity of the wall.  At the same time, the sole being archless, a certain amount of elasticity is lost.  The weight is thrown more on to the heels, and the os pedis slightly descends, rendering the flatness of the sole even more marked than before.  With the loss of elasticity of the sole concussion makes itself more felt.  The animal is easily lamed, bruised sole becomes frequent, and corns sooner or later make their appearance.

Treatment.—­Flat-foot is incurable.  All that can be done is to pay careful attention to the shoeing, and so prevent the condition from being aggravated.  In trimming the foot the sole should not be touched; the frog, too, should be left alone, and the wall pared only so far as regards broken and jagged pieces.

The most suitable shoe is one moderately seated.  If the seating is excessive, and bearing allowed only on the wall, there is a tendency for the wall to be pushed outwards, and for the sole to drop still further.  On the other hand, if the seating is insufficient, or the web of the shoe too wide, and too great a bearing thus given to the sole, then we get, first, an undue pressure upon the last-named portion of the foot a bruise, and, finally, lameness.  The correct bearing should take in the whole of the wall and the whole of the white line, and should just impinge upon the sole.  Above all, the heels of the shoe should be of full length, otherwise, if the shoe is worn just a little too long, its heels are carried under the sole of the foot, and by pressure there produce a corn.

If, with these precautions in shoeing flat-foot, tenderness still persists, a sole of leather or gutta-percha must be used with the shoe.

D. PUMICED-FOOT, DROPPED SOLE, OR CONVEX SOLE.

Definition.—­This term is applied to the foot when the shape of the sole is comparable to the bottom of a saucer.  When least marked it is really an aggravated form of flat-foot.

Symptoms.—­In pumiced-foot the sole projects beyond the level of the wall.  The obliquity of the latter is more marked than in the previous condition, and progression, to a large extent, takes place upon the heels.  In addition to its deformity, the horn is greatly altered in quality, and, as the name ‘pumice’ indicates, is more or less porous in appearance, bulging, and brittle.

Causes.—­As a general rule, it may be taken that pumiced-foot is a sequel of previous disease, although in its least pronounced form it may occur as the result of accidental or other causes, such as those described in the causation of flat-foot.