318 MANUAL OF MODERN FARRIERY. 



various diseases to which it is applicable. Blisters act on 

 the principle that two intense states of inflammation cannot 

 exist in contiguous parts of the system at one time ; therefore 

 we apply some acrimonious substance to the skin to induce ex- 

 ternal inflammation, to draw away that existing in some deeper 

 contiguous parts. Upon this principle we apply a blister to 

 the side in cases of inflammation of the lungs ; for inflam- 

 mation of the bowels, we blister the belly ; the legs are 

 blistered for that of the cellular substance surrounding the 

 sheaths of the tendons ; and for inflammation of the navi- 

 cular joint, Ave make the coronet or heel the medium of 

 operations. Besides their use in inflammation, blisters are 

 useful in increasing the activity of the vessels contiguous to 

 the places where they are applied. In cases of strangles, 

 for example, a blister is used to induce earlier suppuration. 

 Such is the power of blisters, that they will excite the 

 absorbents to greater energy, and by this means they will 

 carry away tumours, and callous, and even bony substances. 



In the application of blisters there is some nicety re- 

 quired to determine when a stronger or weaker one must 

 be applied ; whether by long-continued, or sudden and 

 violent action, the desired effect is most likely to be pro- 

 duced. In inflammatory cases, strong blisters will be found 

 best; but in old and long-seated tumours and swellings, 

 milder means must be adopted. 



It is necessary to prepare the skin of the horse for a 

 blister, by clipping ofi" or shaving closely all the hair of the 

 part where it is to be applied. The best composition for a 

 blister is Spanish flies, lard, and resin, in the proportions for 

 which we have given a recipe at page 59. This should be 

 thoroughly rubbed in, otherwise it will not rise. After the 

 application of a blister the head of the horse must be tied 

 up for at least two days, to prevent him from disfiguring 



