ACUTE INFLAMMATION OF THE PODOPHYLLOUS MEMBRANE. 
769 
tissue of the rete mucosum and entrance of infectious material. Let 
us imagine that a nail has penetrated the hoof as far as this layer, 
but soon after has been removed. Septic products, &c., penetrate by 
the nail tract as far as the rete mucosum, and may give rise to extended 
inflammation. In such cases we speak of a prick or stab. If, on the 
other hand, the point of entrance was an opening between the wall 
and sole, the condition is termed separation ; while if it occur in the 
angle of the heel, we speak of a corn. 
Aseptic inflammation of this tissue, though rare, is seen during 
laminitis and formation of horn tumours, &c. In these cases the rete 
mucosum is sometimes thickened, as shown in laminitis, by increase in 
width of the white line. The horn produced during inflammation is 
sometimes changed in character, stained yellow, or infiltrated with 
blood (corns). Infectious pododermatitis superficialis, on the other 
hand, is always accompanied by suppuration, if we are justified in 
describing the product as pus. Strictly speaking, the thick layers of 
rete break down under the action of the infective material, though 
exudation certainly occurs in the neighbouring portions of the corium. 
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 infectious form is seldom followed by resolution, 
but 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 out¬ 
wardly, 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 process extends, and the fluid forces 
its way along the laminae as far as the coronet, which it perforates by 
thrusting apart the coronary band and commencement of the horny wall, 
appearing, therefore, at the top of the coronet “ 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, 
v.s. 3 i) 
