Symptoms.—­In every case the fissure, or evidence of its commencement, is a diagnostic symptom.  It is well to remember, however, that this may be easily overlooked, especially when the crack is one commencing at the coronary margin.  The reason is this:  Sand-cracks in this position often commence in the wall proper, and not in the periople.  They may, in fact, be first observed as a fine separation of the horn fibres immediately beneath the perioplic covering.  A crack of this description may even show haemorrhage, and have been in existence for some time, without the periople itself showing any lesion whatever.  Thus, unless lameness is present, or a more than specially keen search is directed to the parts in question, the sand-crack goes undiscovered, until of greater dimensions.

Further, the fissure may be hidden, either accidentally or of set purpose.  It may be covered by the hair, filled in and covered over with mud, or intentionally concealed by being ‘stopped’ with an artificial horn, with wax, or with gutta-percha, or, as is more common, be hidden by the lavish application of a greasy hoof-dressing.

In this latter connection it is well to warn the veterinary surgeon, especially the beginner, when examining for soundness, to be keenly critical before passing an animal who is presented with feet smothered with tar and grease or any other dressing.  More especially should this warning be heeded when examining any of the heavier breeds of animal with an abundance of hair about the coronet.

Referring again to the search for the crack, it is well to know that with toe-crack the fissure is the more readily seen when the foot is lifted from the ground.  With quarter-crack, on the other hand, the fissure is wider, and consequently the easier detected with the foot bearing weight.

Although commencing in the insidious manner we have described, the lesion is not thus often seen by the veterinary surgeon.  Usually, the animal with sand-crack is brought for his inspection when lameness has arisen from it.  In this case the cause for the lameness will reveal itself in the crack, which is now too large to escape observation.  The coronet is hot and tender to the touch, and a sensation of warmth is sometimes conveyed to the hand by the horn of the surrounding parts of the wall.  It is hardly necessary to say that, with accompanying conditions such as these, the sand-crack is a deep one.

Where the lameness is but slight, we may attribute it almost solely to the pain occasioned by the mere wounding of the keratogenous membrane, and to no very extensive inflammatory changes therein.  By some authorities this is said to be due to the pinching of the sensitive structures between the edges of the fissure in the horny covering.  In our opinion, however, pinching does not occur unless inflammatory exudation into the sensitive structures adjoining the crack has led to sufficient swelling to cause them to protrude.  In other words, the movements of the horny box, communicating themselves to the structures beneath, and so occasioning movement in the wounded keratogenous membrane, are quite sufficient to give rise to the lameness without actual pinching of the structures implicated.