DISEASES OF HORSES 183 



cema, predispose to gangrene. As external causes we have acids and 

 alkalis, freezing and 'burning, contusions and continuous pressure 

 that interrupt the circulation. There are two forms of gangrene 

 dry and moist. Dry gangrene is most often seen in horses from con- 

 tinuous lying down or from uneven pressure of some portion of the 

 harness. 



Symptoms. There is a lack of sensation due to the death of 

 nerves. In dry gangrene the skin is leathery and harsh, while in 

 moist gangrene the tissues are soft, wrinkled, and friable; the hair 

 is disturbed, and the skin is usually moist and soapy and sometimes 

 covered with blebs. The tissue surrounding the moist gangrenous 

 patch is usually inflamed, swollen, and hot, but this is less noticeable 

 in the case of dry gangrene. Moist gangrene often spreads and in- 

 volves deeper tissue, sheaths of tendons and joints producing septic 

 synovitis or septic arthritis leading to pyemia and death. Dry gan- 

 grene is seldom dangerous, but the rapidity of its spread will indicate 

 its virulence. 



Treatment. The preventive treatment consists in avoiding all 

 the influences that tend to disturb the nutrition of the tissues, such as 

 excessive cold or heat or continuous pressure. Gangrene following 

 decubitis may be prevented by using soft bedding and frequently 

 turning the animal from one side to the other. In dry gangrene 

 moist heat in the form of poultices or anointing the tissue with 

 oils and fats will be found beneficial in hastening the dead tissue 

 to slough off. AVhen the outer skin begins to suppurate, seize it with 

 a pair of pincers and draw it away. After this treat the patch as an 

 open wound. In moist gangrene the tissue should be thoroughly 

 disinfected with creolin, or particularly an alcoholic tincture of cam- 

 phor. Continuous irritation with antiseptic fluids prevents the accu- 

 mulation and absorption of poisonous liquids. Incisions into the 

 dead tissue may be made, and when sloughing commences the tissue 

 should be removed with forceps and the resulting wound treated as 

 in dry gangrene. 



ULCERATION. 



An ulcer is a circumscribed area of necrosis occurring on the 

 skin or mucous membrane and covered with granulation tissue. It 

 is a process of destruction, and when this process is going on faster 

 than regeneration can take place, we have a gnawing, or eating, 

 ulcer. When such an ulcer increases rapidly in size it is termed a 

 phagedenic ulcer. A fungoid ulcer is one in which the bottom of 

 the ulcer projects beyond the edge of the skin. These ulcers secrete 

 milky or bloody-white liquid called ichor. When the ulcer is of an 

 ashen or leaden color, with the 'bottom and sides formed of dense, 

 hard connective tissue which gives but little discharge and is not 

 sensitive, it is termed callous, torpid, or indolent ulcer. 



Causes. As in the case of gangrene, disturbances of circulation 

 are among the most frequent causes. A wound to a tissue with slight 

 recuperative power may be followed by ulceration, as in tumors. 

 Certain germs may produce ulcers, as the glanders bacilli, which 

 cause the ulcerations on the nasal septum in glanders. 



