USES OF IRRITANTS AND COUNTERIRRITANTS 335 



may influence the neighboring organs in two ways. 1. Cause hy- 

 peremia of the organs along with its own hyperemia, or 2. may 

 ■withdraw blood from the organs and leave them anemic. In one case 

 a better blood supply is obtained for the part and better conditions 

 made for the absorption of the exudate. The increased blood supply 

 means an increased nutrition of the part which really aids nature 

 in overcoming some pathological condition. Firing or blistering for 

 spavin or diseases of the joints produces a reparative inflammation 

 which assists nature in locking the bones together so that pain and 

 lameness is relieved. At the same time it assists by producing a 

 period of rest for the part which is also useful in these conditions. 



The use of irritants for the removal of exudates from connective 

 tissue can be explaned by the increased circulation and nutrition. To 

 produce a change in the vascularity of the skin and remove inflam- 

 matory exudates, it is necessary to employ deeply acting and per- 

 sistent stimulation. 



5. Relieve Pain. It has been known for many years that the 

 application of heat or counterirritants in certain superficial areas 

 would relieve pain and inflammatory processes in the deeper organs. 

 The use of counterirritants for this purpose was purely empirical 

 but nevertheless effective and could not be satisfactorily explained 

 for a long time. Mackenzie and Head working upon the inervation 

 of the viscera have somewhat cleared up the matter in case of man. 

 They found that disease of the viscera is often accompanied by ten- 

 derness of the skin and underlying muscles, and that the pain arising 

 in these cases is referred to this area and not to the organ involved. 

 Thus in painful diseases of the stomach, tenderness is often found 

 in the skin and muscles of the epigastrium. In heart disease the pain 

 is often in the left chest wall and shoulder extending down the arm. 

 It was found also that the internal organs and definite areas upon the 

 surface of the body receive their nerve supply from the same spinal 

 or cranial segment and that irritation of one will react upon the 

 other. It is interesting to know that the areas marked out experi- 

 mentally on the surface of the body, as those affected by internal dis- 

 ease, correspond very closely to those areas used empirically, and 

 upon which experience has shovsm irritation to be most beneficial. 



Counterirritants are usually employed in the form of liniments, 

 i.e., in solution or suspension in oils or alcohol. These liniments are 

 too numerous to mention. Likewise the drugs used for counterirri- 

 tation are numerous and only those will be mentioned here that are 

 used especially for this purpose. 



Most important counterirritants are: 



