ACUTE INFLAMMATION OF THE KERATOGENOUS MEMBRANE. 1045 



by a sinuous opening in the coronet, or the hollow of the pastern, 

 it points to synovitis of the lower sesamoid sheath, or to arthritis 

 of the pedal-joint. The significance of these peculiar characters 

 in the pus is again controlled by the degree of pain and general 

 disturbance. 



The attack may terminate either in resolution, abscess formation, 

 or necrosis. The first rarely happens. Much more frequently an 

 abscess forms, similar to those in other positions, and leads to either— 

 necrosis of the sensitive membrane, purulent cellulitis, or systemic 

 infection. 



Necrosis usually depends on infection with particularly virulent 

 bacteria, or the necrosis bacillus, though it is favoured by the position 

 of the sensitive laminae and sole between the unyielding horn on the 

 one side and the os pedis on the other, which causes any considerable 

 swelling to be followed by severe compression and interference with 

 circulation. If the first point involved is one where the sensitive 

 structure lies closely in contact with the bone (as is the case over 

 the greater part of the sole and wall), necrosis frequently attacks 

 the os pedis. Purulent cellulitis can, of course, only occur in 

 structures possessing a subcutis, like the frog and coronary band 

 and the posterior sections of the keratogenous membrane of the wall 

 and sole. 



Inflammation attacks the connective tissue lying below the coronary 

 band, producing a subcoronary inflammation, which usually involves 

 one-half of the hoof, occasionally the whole, and is recognised by 

 the severe swelling and intense pain around the coronet. As infection 

 may extend into the pedal joint, the condition is grave. When 

 occurring towards the back of the coronet, this form of inflammation 

 generally leads to sinuses or quittors, which, however, are still more 

 often the result of suppuration in the posterior sections of the 

 sensitive sole or wall, where the subcutis is in contact with the lateral 

 cartilages. 



Parenchymatous pododermatitis in the sensitive frog often causes 

 purulent cellulitis of the plantar cushion, and is particularly dangerous, 

 on account of so often extending to the flexor pedis perforans tendon 

 and producing necrosis. Purulent cellulitis of the cushion is distin- 

 guished by the violent pain shown, especially on dorsal flexion of the 

 phalanges. When weight is placed on the affected limb the parts 

 are kept in a condition of excessive volar flexion ; weight can only 

 be borne for a moment, and the animal puts down the foot with the 

 front of the wall quite upright, or directed downwards and backwards. 

 Swelling appears in the hollow of the heel ; after some time abscesses 



