1(144 DISEASES OF THE FOOT. 



This explains the tendency of the process to remain confined to the 

 surface, and to extend along it towards the coronet, or, when the 

 white line is the seat of attack, to extend along the thick layers of 

 non-horny rete cells of which it consists. 



Though aseptic pododermatitis superficialis ends in resolution or 

 chronic thickening, the infective form is seldom followed by resolution, 

 hut the pus escapes outwardly, or into the cutis or subcutis, in which 

 it produces inflammation. That the broken-down masses of rete 

 do at times become absorbed is shown by the spaces occasionally 

 found in the horn when cutting out a hoof. The same condition is 

 often seen in the claws of herbivora. Sometimes several spaces are 

 discovered one above the other, showing that the process has occurred 

 repeatedly, and been interrupted by periods of normal horn formation. 



As a rule, septic pododermatitis superficialis ends in perforation 

 outwardly, though it often requires surgical assistance. The 

 condition having been diagnosed and the horn cut away, a greasy, 

 blackish fluid, termed horn pus, escapes, and the animal soon recovers 

 if the parts be properly dressed and protected against fresh injury 

 or infection. When, however, an artificial opening is not made the 

 infecting process extends, and the pus, accumulating between the 

 lamina? and horny wall, reaches the coronet, where it forms an abscess 

 " between hair and hoof." Inflammation of the lower border of the 

 laminae, or periphery of the sensitive sole, generally extends in the 

 direction of the white line, and the pus, therefore, tends to escape 

 at the heel. The discharge of fluid, grey or blackish material, termed 

 " horn pus," at the coronet or heels, and the absence of marked swelling, 

 point to the superficial nature of the attack. 



(2) Pododermatitis parenchymatosa affects the corium or subcutis, 

 and is generally associated with disease of the surface, from which 

 it may originate, though it also results from deeper injuries, like 

 pricks, &c. The podophyllous membrane, or its subcutis, forms the 

 seat of acute inflammation, accompanied by exudation ; suppuration 

 almost always occurs, the pus being precisely similar in character 

 to that formed in other portions of the skin, and appearing thick, 

 yellow, and creamy, while, if its formation is accompanied by necrosis, 

 it may be offensive. The character of the discharge, in fact, is a 

 very valuable indication for diagnostic purposes. When white, 

 yellowish or creamy, the keratogenous membrane is evidently 

 suppurating ; if reddish, or of the colour of wine lees, and stinking, 

 it indicates diffuse necrosis of the membrane, which, again, is often 

 accompanied by necrosis of the os pedis ; when yellowish, viscous, 

 " curdled," or containing fibrinous flocculi, and especially if escaping 



