166 VETERINARY MEDICINE AND SURGERY.. 



The vesicles wliicli characterize eczema are usually developed at the 

 orifices of the cutaneous follicles, are easily ruptured, and discharge a 

 fluid which is glutinous and irritating to the skin. When the vesicles 

 are not ruptured, they terminate by absorption of the fluid; but the dis- 

 ease does not often come to an end with the drying up of one crop of 

 vesicles. More commonly, the eruption is successive, and crop after 

 crop of vesicles is formed; or the surface, on which they first appeared, 

 remains red and raw, and continues to discharge a fluid resembling that 

 contained in the vesicles. After the disease has existed some time, there 

 is a thickening of the derma, which becomes corrugated, more especially 

 in those parts of the body where the skin is naturally loose and movable. 



The individual vesicles of eczema do not last long, and in some cases 

 no vesicles are found; but the skin is inflamed, and fissures make their 

 appearance in the epidermis. These fissures are at first suj)erficial, but 

 become deeper if the disease continues. Eczema characterized by fissures 

 is generally a chronic form of the disease. The various forms of eczema 

 which affect horses are: eczema simplex or humid tetter, lichen, and 

 eczemp. pustulosum or grease. 



Eczema Simplex, Humid Tetter, 



is a non-contagious disease, and it usually commences about the neck 

 shoulders, back, and thighs. It usually comes on suddenly, and is mani- 

 fested by itchiness, which causes the animal to rub and bite itself until 

 the hair and cuticle are brought off, leaving the skin red, raw, and in- 

 flamed. Successive crops of vesicles develop themselves, dry on the sore 

 skin, or discharge a fluid which seems to cause an extension of the dis- 

 order. The parts of the body most usually affected are those which are 

 covered by the saddle or harness; but it may affect any part, such as the 

 head, neck, quarters, thighs, and forearms. It is generally called mange, 

 but it differs from true scabies in two essential particulars, namely, it 

 is not contagious, and does not depend upon the presence of a parasite. 



Eczema simplex is sometimes very troublesome and difficult to treat. 

 In some horses it occurs periodically, or when an alteration is made in 

 the diet. 



Etiology. — In the summer, horses are subject to it when first put 

 on green food, and almost invariably an animal which has suffered from 

 one attack is liable to a recurrence. 



