DISEASES. 667 



time the j)us oozes through the lacunoe of the frog, while again it 

 may then aj^pear at the heels, after making its way under the en- 

 tire sole. 



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 aj)pearance and becomes of livid yellow-greenish color, 

 while at the same time a process of elimination takes place in the 

 surroimding parts, and pas forms, separating the dead tissues 

 from the healthy structure surrounding. This process of elimina- 

 tion 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 jDlantar aponeurosis, or of the os pedis, and some- 

 times of caries of the lateral cartilages, or cartilaginous quittor. 



Causes. — Furuncle of the frog always proceeds from some vio- 

 lent injury through the horny envelope of the tissues it covers, 

 either when the hoof has been cut through and through by a 

 sharp instrument, or as the result of some simple bruise with- 

 out solution of continuity, contusion, or even crushing. Any for- 

 eign body likely to produce a punctui-ed wound of the foot may 

 produce it. But in such cases as are accompanied by furuncle it 

 is necessary that the wound should be more of a contused or 

 bruised than of the punctured variety. Kough, angular stones 

 are the most common agents of injury, being often picked up be- 

 tween the shoe and the frog, and then, pressing more or less upon 

 the tissues underneath, they produce the same result when they 

 are located in laminae of the frog. 



A thick, voluminous frog in a foot with low heels is very much 

 exposed to the class of injuries under discussion, equally with the 

 frog whose horny covering has been pared too closely. 



Treatment. — The first indication, says H. Bouley, when one 

 has to treat a furuncle of the frog, is to thin down as much as 

 possible the horn of the plantar region, and especially that of the 

 frog, of the bars and the branches of the sole, in order to avoid 

 the painful pressure it would produce if its thickness should in- 

 terfere with the expansion of the parts. This done, if the frog is 

 already punctured, and there is an opening communicating Avith 

 the cavity where the core (or boitrbillon) exists, a free incision or 

 opening must be made through the hoof and the fibrous covering 



