Treatment.—­It is doubtful whether anything satisfactory can be recommended.  When we have suspected this condition ourselves, it has been our practice to groove the hoof on either side of the toe, after the manner illustrated in Fig. 120, and, at the same time, point-firing the coronet and applying a smart cantharides blister.  Certainly, after this operation, lameness has often disappeared—­whether, however, as a result of the treatment adopted or by reason of the structures within accommodating themselves to the condition, we would not care to say.

[Illustration:  FIG. 133.—­OS PEDIS SHOWING THE GROOVE IN IT CAUSED BY ATROPHY AND ABSORPTION INDUCED BY PRESSURE OF A KERAPHYLLOCELE.]

Other writers advocate the removal of that portion of the wall to which the tumour is attached, after the manner described on p. 182, and illustrated in Fig. 98.  This, however, should be a last resource, and should be adopted only when weighty reasons, such as excessive and otherwise incurable lameness, appear to demand it.

4.  KERATOMA.

In our nomenclature the terms ‘Keratoma’ and ‘Keraphyllocele’ are both used to indicate the condition we have just described.  There are some, however, who reserve the term ‘Keratoma’ for horny tumours occurring only on the sole, and for that reason we draw special attention to the word here.  Keratoma may thus be used to describe what we have called keraphyllocele directly that growth makes its appearance at the sole, and is there able to be cut with the knife.  Similar hard and condensed growths may, however, make their appearance on the sole in other positions quite removed from the white line, plainly being secreted by the villous tissue of the sensitive sole, and having no connection whatever with the sensitive laminae.  They appear as circular patches, varying in size from a shilling to a two-shilling piece.  Compared with the surrounding horn, they stand out white and glistening, while in structure they are dense and hard, and offer a certain amount of resistance to the knife.  They are of quite minor importance, and, beyond keeping them well pared down, need no attention.  Keratoma probably offers us the best analogy we have to corn of the human subject.

5.  THRUSH.

Definition.—­A disease of the frog characterized by a discharge from it of a black and offensive pus, and accompanied by more or less wasting of the organ.

Causes.—­The primary cause of this affection is doubtless the infection of the horn, and later the sensitive structures, with matter from the ground.  Those factors, therefore, leading to deterioration of the horn, and so exposing it to infection, may be considered here.  Such will be changes from excessive dampness to dryness, or vice versa; work upon hard and stony roads; prolonged standing in the accumulated wet and filth of insanitary stables, or long standing upon a bedding which, although dry, is of unsuitable material.