CRACKED HEELS—GANGRENOUS DERMATITIS—GREASE. 
649 
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 antiseptic pre¬ 
cautions. 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 
sterilises the point of operation. In quiet animals, the parts may be 
removed whilst standing ; if necessary, cocain can be locally injected. 
Bestive horses should be cast. The foot is extended as far as possible 
- in the case of the hind foot, it may be bound to the 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 inches 
in size, otherwise cicatrisation proves difficult, and the growth is 
inclined to recur. Moller repeatedly removed growths of this kind from 
the hind pastern, and cured cases in which medical treatment had 
proved useless. 
(8) Dermatitis gangrenosa has a special surgical interest, because it 
often forms the first of a series of diseases which call for the display of 
surgical skill. It consists in spontaneous gangrene of the skin of the 
phalanges, occurs in solipeds, particularly during winter, and is oftenest 
seen in large towns. One of its commonest and simplest forms is known 
as “ cracked heel.” 
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. The fact 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, on account of its 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 gangrenous 
spot. They are, however, generally absent. The experiments of Siedam- 
grotzky and Jelkmann showed that the lowering of temperature, conse¬ 
quent on the use of salt (which is particularly common in large towns), 
could not be held responsible for the production of the disease. And, 
finally, it should be noted that at times, when gangrenous dermatitis is 
common, all wounds show a tendency to gangrene. It, therefore, seems 
tolerably clear that local freezing is not the only cause, but that other 
