LOCAL INFLAMMATIONS 143 



the upper part of the body, extensive eruption along the centre of the 

 back has been observed, in cattle particularly. It will be noticed that 

 the degree of irritation produced is largely dependent upon the sen- 

 sibility of the skin; when this is thin and delicate, the application of 

 mustard or ammonia will often produce extensive erythema, followed by 

 the formation of vesicles, and ultimately desquamation of the cuticle, 

 and maybe a superficial ulceration, while the same agent applied to an 

 animal with a coarse skin produces little or no effect. The use of arsenic 

 as a caustic in the treatment of warts has sometimes caused extensive 

 inflammation of the skin surrounding the wart, with considerable slough- 

 ing. It has already been stated that horses working where the ground 

 is covered with lime suffer from inflammation of the skin of the legs, 

 accompanied by cracks or fissures. Sometimes inflammation of the glandu- 

 lar structures of the skin arises out of the same cause, accompanied by 

 a considerable discharge of sebaceous fluid. 



Internal agents, such as articles of food and various drugs, give rise 

 to eruptions in the skin of susceptible subjects; the eruption known as 

 nettle-rash following the eating of mussels and other shell-fish by man 

 is an instance of an eruption following the consumption of certain kinds 

 of food. Medicinal agents are responsible for a large number of disorders 

 of the skin, of the erythematous, papular, vesicular, and bullous type, 

 all of which are known as drug eruptions. The occurrence of these diseases 

 in the skin of the lower animals from the use of different drugs has not 

 been recognized by veterinary writers, but there is no reason to doubt that 

 they may occur from the continued employment for medicinal purposes 

 of bromides, iodides, mercury, arsenic, salicylic acid, and other agents. 

 Salicylic acid certainly has a marked local effect when given in con- 

 siderable doses to cattle for the removal of large pendulous warts; after 

 the use of the agent for this purpose for some weeks, the skin near 

 the warts becomes inflamed, and the warts fall off in succession, leaving 

 the raw surface, which rapidly heals. The use of the agent is then, of 

 course, discontinued. 



The fact of the occurrence of eruptions of different kinds from the 

 action of external and internal agents should, under all circumstances, be 

 taken into account in forming a diagnosis. 



LOCAL INFLAMMATIONS 



A considerable number of the most common affections of the skin of 

 the horse, among them erythema, urticaria, eczema, ecthyma, &c., come 

 under the head of local inflammations. 



