1060 DISEASES OF THE FOOT. 



goes on while the coronet is still swollen. In exceptional cases, this 

 thickening may take place on the inner surface, producing a horn 

 tumour. 



In addition to such complications, more dangerous consequences 

 may follow treads. If, for instance, in consequence of direct injury 

 to the joint, or its infection during an attack of purulent cellulitis in 

 the subcoronary connective tissue, or of extension of necrosis towards 

 the depths, purulent inflammation attacks the pedal-joint, the 

 condition becomes incurable. 



Necrosis of the extensor pedis tendon produces severe lameness ; 

 when the foot is extended, or attempts are made to bear weight on it, 

 the lower part of the limb assumes a position of excessive volar flexion. 

 The condition, however, may involve no permanent injury, the 

 defect in the tendon being replaced by connective tissue, which 

 firmly unites the ends. Extension of necrosis to the sensitive laminae 

 is dangerous, because of its tendency to involve large areas, leading to 

 diffuse inflammation of the sensitive structures, which may be followed 

 by loss of the hoof. Necrosis of the lateral cartilage always produces 

 quittor. 



Prognosis. The consequences of treads may be exceedingly varied. 

 The following points are of chief importance : — 



(1) The position and extent of injury. The more nearly the 

 injury approaches the coronary band, the graver it becomes. If 

 the skin and upper part of the horny wall are alone injured, and the 

 wound is not deep, healing soon follows ; but treads on the coronary 

 band not only offer great obstacles to treatment, but may involve 

 the pedal-joint, especially in the small, clean feet of well-bred horses. 

 At the centre of the toe the pedal- joint lies scarcely more than 

 | of an inch below the coronary border of the horn, but as we pass 

 back it recedes from the coronet, and is therefore less easily injured. 

 For this reason, and also because of the danger of injury to the extensor 

 pedis tendon, injuries at the front are always more dangerous than 

 those at the side of the foot. 



(2) The size of the swelling and degree of lameness. As probing 

 gives no reliable information of the extent of the injury, and may 

 produce perforation of the pedal-joint, or introduce infective sub- 

 stances into the depths of the wound, in forming a prognosis, the 

 amount of swelling and pain must be considered. Particular reticence 

 should be observed when the parts are exceedingly painful but swelling 

 is limited, especially if the pain is without visible cause. The general 

 condition, appetite, temperature, &c.,must, of course, not be neglected 

 in forming a prognosis. 



