846 Eczema. 



consequently occurs mostly in those parts of the body that are 

 most subject to soiling, or which the animal is not able to clean 

 thoroughly. Accordingly those parts of the body are affected 

 principally which are covered with long hair, such as the tail 

 and mane in horses where the dirt collects in large quantities at 

 the roots of the hair, and on the back which is a favorite locali- 

 zation of the trouble in long-haired dogs. 



Dampness also plays an important part, insofar as by 

 softening its horny layer, it deprives the skin of its natural pro- 

 tection, and at the same thne it promotes a firmer sticking of 

 particles of dirt and the proliferation of fungi on the skin, and 

 also a closer contact of the superficial with the deeper layers. 

 For this reason the disease occurs in sheep after continuous 

 rainy weather, affecting the back and croup, especially if the 

 fleece is very close. In dogs eczema occasionally results from 

 over-frequent washing, especially with green soap, which be- 

 sides a loosening effect also exerts an irritating action on the 

 skin. On the fetlocks of horses and cattle, pasturing on dew- 

 covered meadows may give rise to eczema. Eczema (Sudamina) 

 also develops in long continued diarrhea in the neighborhood 

 of the anus, in dribbling of urine in the neighborhood of the 

 urethral opening, further, on parts of the skin that sweat pro- 

 fusely, especially between the folds of thin skin; but in this 

 case the excretions or secretions with their irritating constitu- 

 ents and products of decomposition are important factors. The 

 continued effect of dampness and dirt must be held responsible 

 for the eczema occurring on the fetlocks of horses and cattle, 

 but seldom on those of sheep ("Mauke"). 



Mechanical influences, such as insect stings, rubbing, pres- 

 sure, bites, may easily cause eczema if frequently repeated or 

 if the skin sweats and is dirty. In the presence of animal para- 

 sites (flies, lice, ticks) not only the stings but also the factors 

 already mentioned, and the prevailing uncleanliness are to be 

 considered as immediate causes, the same being true in the 

 case of eczema accompanying scab and in eczema at the root 

 of the tail in the presence of oxyuris eggs. In working animals, 

 especially in horses, the disease occurs especially at those parts 

 of the body which are subject to the pressure and the chafing 

 of the harness or saddle, and here again constant intense sweat- 

 ing plays a part. The simultaneous effect of chafing and sweat- 

 ing may finally be seen in eczema occurring on parts of the skin 

 that come in contact and rub on each other between the thighs, 

 at the root of the tail, and in eczema occurring at times around 

 the anus (E. intertrigo). The mechanical influences are further 

 of importance in that they create a loss of substance in the epi- 

 dermal layer of the skin, and render possible the penetration 

 of microorganisms into the tissue of the cutis. 



The influence of great heat may cause an eczema on the un- 

 pigmented portions of the skin (E. caloricum), and the same can 

 develop on spots that are exposed for a long period to the hot 



