DISEASES. 633 



tula, a warm swelling forms itself in the back of the coronet, which 

 raises the skin by degrees and becomes elevated, prominent at 

 one point, and giving a feeling of fluctuation. This swelling ends 

 in ulceration, and allows the escape sometimes of an abundant 

 synovial, purulent discharge. 



The wound of the small sesamoid and of its Hgament adds 

 nothing to these series of symptoms. The probing of the tract 

 wiU only determine it by the sensation of roughness which it will 

 give ; but generally one must be careful in using the probe, es- 

 pecially when the flow of synovia is absent. If the foreign body 

 has pierced through the Hgament, or has penetrated in the coffin 

 joint, phalangeal arthritis is the consequence. The same result is 

 likely to follow excessive inflammation of the foot and the macer- 

 ating effect of the suppuration, in which case the tendon may 

 soften down and give way. It may then also happen that this 

 tendon retracts by the contraction of the muscular fibres, and can 

 then be traced upward to the back of the coronet, or of the fet- 

 lock, according as the giving way has taken place higher or lower. 



With arthritis there is a hot, painful swelling of the whole cor- 

 onet, with diffused oedema above the fetlock and the cannon, and 

 extending upward to the whole leg, complicating the lesion by lym- 

 phangitis, and painful swelling of the lymphatic glands. Then sub- 

 cutaneous abscesses are found round the coronet, with gangrene 

 of the tissues ; whUe, again there may be only an extensive fibro- 

 plastic exudation, which ends in calcarious organization and anchy- 

 losis. 



In the anterior zone the only serious lesion met with is caries 

 of the OS pedis, characterized by great pain, continual lancination, 

 loss of the use of the leg, and high reacting fever. There is 

 abundant bloody and fcetid suppuration, and the probe gives the 

 sensation of the softresistance of the bone, of its rough condition, 

 and its partial fragility. The caries having most generally a pro- 

 gressive march, complications of separation of the hoof, to a vary- 

 ing extent, are often seen ; the pus arrives at the surface between 

 hairs and hoof; and diffused gangrenes are also often seen, which 

 extend as well to the podophyllous as to the velvety tissues. 



In the posterior zone, the only serious wounds are the lateral 

 ones, which may injure the fibro-cartilage and become complicated 

 with their caries or quittor and fistula down to the lacunte of the 

 frog, as we have seen in suppurating corn. 



