GANGRENOUS DERMATITIS. 917 



spot is again cleansed and the dressing renewed. Daily immersion 

 of the affected heels in a warm astringent bath, followed by dry 

 dressing and bandaging, often hastens recovery 



To check excessive proliferation (*' proud flesh ") and to promote 

 cicatrisation, astringents like alum or sulphate of zinc may first be 

 tried ; and in the event of their proving unsuccessful, the actual 

 cautery, nitrate of silver-, or sulphate of copper, is often of service. 

 Cicatrices which project above the skin, or which, from contraction, 

 have become hard and sharply marginated, can only be dealt with by 

 the knife, caustics being in most cases useless. The portions of 

 growth overtopping the neighbouring skin are removed, with anti- 

 septic precautions. The parts should be washed with sublimate, 

 creolin, or carbolic solution, and a dressing moistened with one of 

 these materials applied and left in position twenty -four to forty -eight 

 hours. This disinfects the point of operation. In quiet animals, 

 the parts may be removed whilst standing ; if necessary, cocaine 

 can be locally injected. Restive horses should be cast. The foot is 

 extended as far as possible — in the case of the hind foot, it may be 

 bound to a front one. The incisions should be smooth and regular ; 

 bleeding is generally slight, and can be checked by a pressure dressing, 

 which at the same time prevents excessive new growth. By resting 

 the animal and keeping the stall dry, healing is generally complete 

 in eight to fourteen days, provided the growth is not extensive, i.e., 

 not more than 1 to 2 mches in size, otherwise cicatrisation proves 

 difficult, and the growth may recur. Moller repeatedly removed 

 growths of this kind from the hind pastern, and cured cases in which 

 medical treatment had proved useless. 



(c) Dermatitis gangrenosa consists in limited spontaneous necrosis 

 of the skin of the pastern or coronet, occurs particularly during 

 winter, and is oftenest seen in large towns. It has been termed 

 " frost bite," and " coronary sloughing." 



Causes. The fact that gangrenous dermatitis occurs almost always 

 in winter, and especially in cold countries, has suggested the idea 

 that it is due to freezing of the skin. That the disease does not 

 occur so much during periods of excessive cold as during thaws was 

 not held to altogether disprove that view ; for it seems natural that 

 moist cold should be particularly injurious, by neutralising the 

 protection afforded by the hair, and enabling the cold to act directly 

 on the skin. The theory, however, is not in keeping with the local 

 character of the disease. Were cold the sole agent, symptoms of 

 freezing in the first and second degree might fairly be looked for 

 around the necrosing spot. They are, however, generally absent. 



