DISEASES AFFECTING FEET 



or run throughout the entire thickness of the wah, thus causing 

 pain and lameness. The fore or hind feet may be affected, 

 more frequently the former, in which the crack is generally 

 situated upon the inner side — the horn being thinner and having 

 greater weight to bear — but in the hind feet the split is usually 

 in front. Sandcrack may be found at the toe in the fore limbs 

 as well. The horn begins splitting from without to within, or 

 vice versa. It is most important that the layman should bear 

 this in mind, because it forms a strong argument in favour of a 

 sandcrack being capable of sudden onset. A horse might be 

 passed as sound, apparently so, yet the crack becomes evident 

 shortly afterwards. Without the wall is weakened on the inner 

 side m this way, it is hardly likely that the crack will appear 

 suddenly. 



Causes. — The exciting cause is concussion (the wall of the 

 hoof is the chief weight-bearing structure), but predisposition 

 is found to exist in large flat feet. Loss of water, consequently 

 brittleness in the hoof wall, is favoured by the evil practice of 

 rasping the crust, and I think that there can be little hesitation 

 in believing that such is favourable towards the production of 

 sandcrack, though it is certainly not the only cause, the writer 

 (and doubtless others) having seen typical sandcracks in feet 

 that have never been shod. \Miether the splitting of the horn 

 substance (tubular or intertubular), or its defective secretion 

 from the horn-forming material at the coronet be at fault, does 

 not appear to have been accurately determined. It may be 

 that the splitting of the horny tubes is primarily due to this 

 latter cause, sandcrack commonly beginning just below the 

 coronet, i.e., the top of the hoof. False quarter is a predisposing 

 cause. When about to purchase a horse it is well to bear this 



335 



