460 VETERINARY SURGICAL THERAPEUTICS. 
The treatment of caries by actual cauterization goes back to old time : 
it was freely used by old hippiatres, who had borrowed it from human 
surgery. Lafosse, who had seen many of its good results, said: “The red 
iron makes a non-contagious eschar and the suppuration, which follows its. 
application, is a true knife with which nature separates the diseased from 
‘the healthy tissue.” Cauterization not only makes eschars of the carious. 
parts, but it creates in the surrounding region a true, eliminating and 
cicatricial inflammation. Repeated cauterization has often been used. 
uccessfully in. costal caries, which had resisted other forms of treatment. 
The operation must be done according to some rules: when the disease. 
affects bones situated in the neighborhood of important organs (cranium, 
ribs, extremities of long bones), the cauterization must be done slight for 
a few moments, done at several seatings, one or two days apart, to such 
effect that the heat would not penetrate as far as the organs that these 
bones cover or protect; spongy bones should be burnt for a longer time 
than those that are dry or compact, on account of the great quantity of 
fluid which, escaping for the first, rapidly put the heat out, and also be- 
cause caries affects them more deeply. 
A great number of chemical caustics have been advocated against. 
caries; emetic (St. Cyr), chloride of zinc, nitrate of silver, more or less. 
diluted mineral acids, specially sulphuric (Pollock, Mollereau). We do not 
like this treatment. Not only are those agents powerless to arrest the 
caries, but they may give rise to severe disorders in the soft parts which 
cover the diseased bone. 
Every time that one wishes to interfere directly and easily upon the dis- 
eased bone, he must proceed with the removal of the carious tissue. This. 
is the way that all caries of the third phalanx must be operated. There, 
the operation consists in exposing the tegumentary membrane that en- 
velops the phalanx, in freely excising all portions of the velvety and 
podophyllous tissues, which are gangrenous or on the road to mortification ; 
then, with a sage knife, the drawing knife or a curette, remove layer by 
layer the part of bone that is dead, until the surface exposed gives evi- 
dence of its vitality and perfect integrity by its normal resistance, its. 
rutilant coloration on exposure to the air, through the bloody oozing which 
comes from the areolz of the spongy tissue all over its surface. When 
this presents still in some points a bony tissue with a brown, purplish or 
yellow-greenish color and if pressure brings on the oozing of some traces 
of pus or sanious fluid, the curette must hollow all these points, until 
sound spongy tissue is reached ; it is better to scrape some of this than to 
have the smallest portion of diseased tissue left behind. Often, after 
trying to preserve a thin layer of the os pedis, one is obliged, two or three 
days later, to make a large cut in the foot, remove a wide piece of the 
