Eczema of the Swine. 861 



by tlie associated traumatic inflammation of the skin, because 

 then the cutis is exposed through suppuration and tissue de- 

 struction, and even ulceration and purulent inflammation of 

 the subcutaneous connective tissue may be present. In such 

 cases it is possible to form an opinion on the nature of the 

 disease from its locality and history ; moreover, in eczema one 

 often finds small vesicles and moist surfaces at the edges of 

 the more severely inflamed parts of the skin. A special diag- 

 nostic significance attaches particularly to the presence of moist 

 spots (Kaposi recommends in doubtful cases to rub diluted 

 potassium hydrate on the affected skin, whereupon small 

 moist dots or vesicles appear in cases of eczema). The more or 

 less similar diseases with the formation of large crusts on the 

 skin may be differentiated on this basis, since in them a deep 

 necrotic ulcerous base becomes visible after removal of the 

 crusts. 



The demonstration of eczema does not, however, exhaust 

 the requirements of diagnosis, for the discovery of the cause is 

 of great importance, both practically, and from a therapeutic 

 point of view. Skin diseases caused by animal parasites, 

 and especially the ditferent forms of scab frequently exhibit the 

 characteristics of eczematous inflammation, and therefore a 

 mistake in diagnosis is easily possible, especially _ in horses, 

 dogs and swine. A slow^ development at the beginning and 

 increased itching- at night, and in warm places as well as the 

 presence of vesicular eruptions speak in favor of a parasitic 

 cause of the disease, but these signs cannot always be found 

 at every examination even in the severe forms of eczema, and 

 moreover in neglected cases only a severe form of dermatitis 

 is generally present. Acariasis may be easily recognized by 

 the favorite localization of the disease and in the pustulous 

 form by the presence of large nodules and peculiar bluish trans- 

 parent pustules as well as by the fact that the thickening of 

 the skin is always considerable; the squamous form of acarus 

 scab can in many cases only be differentiated from circum- 

 scribed eczema by the aid of the microscope, unless it occurs un- 

 der the form of alopecia areata. Sarcoptic scab is often easily 

 recognized on the basis of its occurrence in certain favorite 

 spots and from the fact that in proportion to the severity of the 

 skin disease the itching is intense, but not infrequently this also 

 is only possible through microscopic examination and by dem- 

 onstrating the transmissibility of the disease. Microscopic ex- 

 amination cannot be avoided, especially in those cases in which 

 the customary treatment of eczema produces no improvement, 

 since it is usually successful in cases that are not advanced too 

 far. In suspected sarcoptic scab the examination often re- 

 quires long and repeated investigation, while the dermatocoptes 

 or dermatophagus mites are easier to find. Larger parasites 

 which subsist and wander on the surface of the skin (ticks, 

 fleas, lice) generally may be found without much difficulty. 



