686 A MANUAL OF VETERINARY PHYSIOLOGY 



tures like the lateral cartilage ; the process is destructive and repair 

 slow. Suppuration around the coronet is a formidable affair ; the 

 parts allow of very little swelling, are rigid and unyielding, and 

 burrowing of pus occurs such as is hardly met with elsewhere. It 

 is the dread in all foot injuries, and is brought about by the manner 

 in which the parts are confined within an unyielding box. There 

 are few diseases more painful, and few of which the surgeon has 

 more genuine dread. Suppuration may follow any injury, from an 

 injury in shoeing to a tread on the coronet. Injuries in Shoeing 

 are generally caused by the nail, occasionally by the foot being over- 

 reduced. A shoeing injury causes intense pain, and, if severe, is 

 followed by considerable destruction within the foot. A frequent 

 injury in the angle between the bar and wall is caused by the heel of 

 the shoe, and known as Corn ; it is due to sole pressure, which in 

 this region especially cannot be tolerated. It is a bruise of the 

 part which is very persistent, and frequently permanent. It has a 

 physiological basis ; the foot grows forward (p. 674) ; it carries the 

 shoe forward, and so takes it off the bars. The heel of the shoe 

 then beds itself into the angle formed by the sole between the wall 

 and bar. Bruise of the Sole may occur at any other part of the 

 sole, but is never followed by permanent results, as is a corn. The 

 sole cannot withstand pressure, especially that caused by a stone 

 becoming wedged between the foot-pad and the shoe. Arthritis 

 from penetrating wounds of the foot is common, but the pedal joint 

 does not suffer from locomotive arthritis, as does, for instance, the 

 joint immediately above it, and many others in the body. Nor do 

 the foot-joint or tendons suffer from sprains, though, under the influ- 

 ence of erosion after neurectomy, the tendon of navicular disease 

 may be worn through and snap, or even the bone fracture. Frac- 

 ture of the Pedis, in spite of its porous nature, is very rare. When it 

 does occur, it rarely unites, though the parts are contained in a 

 permanent splint, which, theoretically, should lead to perfect union. 

 The fact, however, is that, under the influence of the body weight, 

 the fragments are always being forced apart. Nutritive changes 

 occur in the foot after neurectomy, and the hoof may come off ; or 

 so-called gelatinous degeneration of the foot and limb occur as high 

 as where the nerves are divided. Evulsion of the healthy foot may 

 occur as the result of an accident, the foot being caught, for instance, 

 in railway-points, and the animal, in its struggles, pulls the inside 

 foot out of its cover. In such cases the nails in the wall afford such 

 a powerful hold that, rather than allow the shoe to tear away, the 

 hoof is pulled off — an object-lesson in the security afforded by nails, 

 and the hopelessness of ever attaching the shoe by any other means 

 so simple and effective. 



A weak wall in the fore-foot is liable to fracture during dry and 

 hot weather ; it is known as Sand-crack, and its physiology will be 

 understood when the necessity for moisture in the horn is borne 

 in mind (p. 671). The crack always begins at the coronet ; it opens 

 and closes in accordance with the expansion and recoil of the foot, 

 and demonstrates these movements. Sand-crack in a hind-foot is 

 a totally different matter ; it occurs at the toe, extends from bottom 

 to top, and is due to violence, especially in heavy draught. Con- 

 traction of the foot was the great bugbear in days gone by. It was 

 regarded as a disease ; in the present day it is almost entirely a 

 symptom. A foot will contract if it is rested, as in navicular disease, 

 and the cause of this must be evident from what has been said in 



