Although occurring in this way with an acute attack of laminitis, it must be remembered that seedy-toe may arise without previous noticeable cause.  The first intimation the owner has is a report from the forge that seedy-toe is in existence.  To refer to cases so arising a probable cause is far from easy.  At one time it was believed to be due to parasitic infection of the horn.  Others have blamed the pressure of the toe-clip, excessive hammering of the wall, or pressure from nails too large or driven too close.  Others, again, say that seedy-toe may result from a prick in the forge, from hot-fitting of the shoe, from standing on a dry and sandy soil, or from the use of high calkins on the front shoes.  In these cases—­cases with an insidious onset—­we are inclined to the opinion that the disease of the horn commences from below, and that the sensitive laminae become implicated later.  Holding this view, one must account for the commencing disease of the horn by giving, as causes, firstly, those factors (as, for instance, alternate excessive dampness and dryness) leading to disintegration of the horn tubules; secondly, the penetrating into and between the degenerated tubules of parasitic matter from the ground; and, thirdly, the final breaking up of the horn, and spread of the lesion under the invasion thus started.

[Illustration:  FIG. 129.—­DIAGRAM ILLUSTRATING POSITION OF SEEDY-TOE (INTERNAL). 1, The horn of the wall; 2, the horn of the sole; 3, the cavity of the seedy-toe; 4, the os pedis; 5, the keratogenous membrane.]

Symptoms.—­Lameness sometimes attends seedy-toe, and sometimes does not.  This is an important point to be carried in mind by the veterinary surgeon who is accustomed in his practice to have many animals pass through his hands for examination as to soundness.  An animal with advanced seedy-toe—­a condition constituting serious unsoundness—­may walk and trot absolutely sound, and may give no indication, either in the shape of the wall or the condition of the sole, that anything abnormal is in existence.  Later, however, after the veterinary surgeon has passed him, the purchaser lodges the complaint that the horse has a bad seedy-toe, which, so he is told, must have been there for some time.  In this case, culpable though he may appear, there is every excuse for the veterinary surgeon.

Once the cavity is opened at the toe in the neighbourhood of the white line, then diagnosis is easy.  A blunt piece of wood, the farrier’s knife, or a director may be easily passed into it, sometimes as far up as the coronary cushion (see Fig. 129).  Issuing from the opening is seen occasionally a little inspissated pus; more often, however, the dry, mealy-looking detritus to which we have before referred.  This form of the disease we may term ‘Internal Seedy-Toe.’ for, plainly enough, it has had its origin in chronic inflammatory changes in the keratogenous membrane.

[Illustration:  FIG. 130.—­EXTERNAL SEEDY-TOE COMMENCING AT THE PLANTAR BORDER OF THE WALL.]