148 GENERAL THERAPEUTICS FOR VETERINARIANS 



Classification. — The cutaneous irritants are usually divided 

 into the following four subdivisions: 



1. Rubefacients: Turpentine oil, camphor, tincture of arnica, 

 tincture of capsicum, oil of juniper, oil of rosemary, ammonia 

 water, tincture of iodine, Priessnitz dressing, massage. 



2. Vesicants : Cantharides, oil of mustard. 



3. Pustulants: Tartar emetic, croton oil, euphorbium. 



4. Suppurants : Biniodide of mercury, bichromate of potassium. 



Uses. — The cutaneous irritants are of essentially greater prac- 

 tical consideration in veterinary medicine than in human thera- 

 peutics. They are employed with advantage in internal medicine 

 as well as in surgery for the most varied purposes. The most 

 important diseases in which they are used are the following: 



1. Subacute and chronic inflammations, including chronic 

 eczema, also contusions of the skin, the subcutis and the under- 

 lying tendons, tendon sheaths, joints, muscles and bones. Strong 

 cutaneous irritation, such as may be produced by briskly rub- 

 bing in tincture of iodine, cantharides ointment or biniodide of 

 mercury ointment, exerts a heaUng effect in all these surgical condi- 

 tions. An artificial inflammation is generated in the skin which 

 extends to the underlying parts, converting the chronic inflamma- 

 tion into the acute form, which runs a more rapid course; acceler- 

 ating, like firing, the absorption of the exudate and, in painful 

 inflammation of the articulations, hastening the ankylosis and 

 thereby removing the pain and lameness. The method of opera- 

 tion of epispastics has been more exactly studied in connection with 

 tincture of iodine. When the latter substance is painted upon the 

 skin an erysipelatous-like inflammation with cedema formation is 

 produced, which is accompanied by outwandering of the white 

 blood-cells (local hyperleucocytosis), formation of enzymes, Uque- 

 faction of the tissue albumins and softening of the solid disease 

 products (histolysis). Resorption of the inflammatory exudate 

 follows. 



2. Acute inflammations of the lungs, pleura, and peritoneum. 

 The cutaneous irritants first of all draw blood from the internal 

 organs (derivative action). In exudative pleurisy (contagious 



