THE HORSE’S FOOT. 
205 
As the disease progresses, and the necrosed spot develops 
itself, the animal rests his foot better, and the lameness 
diminishes. 
Upon examination of the foot early in the history of the case, 
a small opening may ordinarily be discovered, either on the body 
of the frog or in its branches, while at other times there is merely 
a discharge of a yellowish serous pus of a strong odor, and more 
abundant in quantity than would be expected from the size of the 
wound, while surrounding it the hoof is loose and sometimes 
ready to drop off. If the disease is several days old a mass of 
dead tissues is ordinarily found partly loose, projecting through 
the opening of the frog, which has the aspect of a whitish body, 
slightly green, soft, loose and detached amongst the surrounding 
tissues. 
When this core (bourbillon) is not visible it may sometimes 
be felt with the finger introduced through the wound in the 
frog. 
If there is no lesion of the frog the purulent fluid accumu¬ 
lates under the hoof, raising and loosening it from the velvety 
tissues to a varying extent. Fluctuations may be sometimes 
even felt under the hoof. Sometimes the pus oozes through the 
lacunm of the frog, while again it may then appear at the heels, 
after making its way Tinder the entire sole. 
(II) Pathological Anatomy .—As we said at the beginning, 
the characteristic lesion of the frog is the gangrene of a portion 
of the fibrous structure of the plantar cushion, when it changes 
its general appearance and becomes of livid yellow-greenish color, 
while at the same time a process of elimination takes place in the 
surrounding parts, and pus forms, separating the dead tissues from 
the healthy structure surrounding. This process of elimination 
is more active on the surface than in the deeper parts of the 
plantar cushion, to which very often this core remains attached. 
In some serious cases the disease becomes complicated with ne¬ 
crosis of the plantar aponeurosis, or of the os pedis, and 
sometimes of caries of the lateral cartilages, or cartilaginous 
quittor. 
(in.) Causes ,-*Furuncle of the frog always proceeds from 
