176 DISEASES OF THE FEET. 



and consequently to form a sandorack at any moment. This will 

 naturally be at the point which receives the greatest amount of 

 strain ; usually, the inner quarter of the fore, and the toe of the 

 hind foot. It sometimes occurs at the toe of the fore foot, when 

 the hoof is very flat. I have met with cases of sandcrack brought 

 on by indigestion, on account of the secreting membrane of the 

 hoof participating in the general derangement set up in the diges- 

 tive organs. Although the fissure occurs in a moment, the process 

 which induces the weak condition of horn is necessarily a slow one. 

 The animals most liable to sandcrack are cart and cab horses 

 worked on hard ground. Sandcrack as a rule occurs in two ways : 

 (1) by concussion, which is specially productive of sandcrack in 

 the fore feet ; and (2) by undue strain, as in the hind feet of cart 

 horses which have to drag heavy loads, especially when they are 

 shod behind with toei-pieces. 



SYMPTOMS.— The injury first begins by a small fissure close 

 to the coronet, and extends upwards, downwards, and inwards, as 

 the mischief is aggravated by concussion, or by strain. At first 

 the crack may be so short and narrow as to escape notice unless 

 closely examined. As long as it is confined to the exterior portion 

 of the wall, there will be no lameness ; but if it implicates the 

 entire thickness of the wall, the sensitive, underlying tissues will 

 protrude through the crack, and get pinched and wounded as it 

 opens and shuts during movement, with the unavoidable result, 

 when work is prolonged, of making the animal lame, especially if 

 the toe of the hind foot is the seat of the injury. A rest may 

 cause the disappearance of the lameness, which will certainly re- 

 turn on the resumption of work under previous conditions. In 

 time, the fissure may extend from the coronet to the ground, and 

 may gape considerably. The exposed sensitive tissues, owing to 

 irritation and putrefactive contamination, may discharge pus, 

 which may or may not be mixed with blood. This discharge may 

 be more or less frothy from the fact of the air which enters the 

 crack, becoming churned up with the discharge as the fissure opens 

 and shuts at each step. 



If the injury is at the toe, the crack opens when the foot is 

 raised from the ground, and closes when weight is put on it ; but 

 these actions are reversed when it is at the quarter. This view 

 seems to be borne out by the fact that the lameness of sandcrack 

 at the toe is much more serious than wJien the injury is at the 

 quarter. 



PRINCIPLES OF TREATMENT.— Sandcrack should be treated 

 according to the following principles : — (1) To prevent movement 



