476 Veterinary Medicine. 



and the rhus pumila of West North Carolina. Any one of these, 

 like oil of turpentine (Friedberger-Frohner) will rouse the special 

 susceptibility of the morbid skin and system. 



The same may be said of the bites or stings of insects, especially 

 such as instil an irritant venom — the harvest mite (trombidium 

 holosericeum and Americana, Schindelka), chigoe, wood ticks, 

 hairy caterpillars, (bombyx pityocampa, Pourquieur), acanthia, 

 (bed bug) , ^i?a (pulex), biting flies, bees, hornets, etc. 



The most common exciting cause of urticaria is, however, from 

 within, and especially from the circulation in the blood of poisons 

 generated hi the alimentary canal from particular disturbing 

 kinds of food. These operating on the susceptible skin and 

 nervous system determine the nettle rash as promptly and' 

 severely as will the local irritant or the instilled venom. Among 

 such unwholesome or exciting foods may be named buckwheat, 

 Indian corn, green potatoes, partially ripened oats or other grain, 

 and leguminous seeds, especially if only partially matured. 

 Some animals have a special susceptibility to given articles of 

 food which are in no sense injurious to their fellows but which 

 promptly develop in them a marked urticaria. In other cases 

 an overfeed or an ordinary feed given when the animal is heated 

 and exhausted, failing to meet with prompt antisepsis and diges- 

 tion, passes into fermentation and determines a local irritation 

 and general poisoning which issues in urticaria. A sudden ex- 

 treme change of feed will at times operate in the same way. A 

 sudden change from dry to green food has been particularly in- 

 criminated. 



Other poisons produced in certain morbid processes have a 

 similar result. Thus it has been observed to supervene on invet- 

 erate skin disease in the dog ; on strangles in the horse ; on 

 erysipelas (rothlauf) in swine. It has appeared in the horse 

 during pustiilous dermatitis, acne, and chronic eczema. Finally 

 it may be seen as a complication of renal disorder, or haemoglo- 

 binuria and even as the result of a sudden chill from plunging 

 in cold water, or standing in a cold rainstorm or draught, after 

 profuse perspiration. These all bespeak the presence of poisons 

 in the system, and suggest that still other conditions and their 

 resultant poisons may cause the same eruption. I/Unwitz has 

 seen cases in pigs following exposure to the burning rays of the 

 sun. 



