NETTLE-RASH 615 



are pressed upon with the finger the bright-red color disappears, 

 and returns again as soon as the finger is removed. 



Course. — Erythema is a simple condition except when it occurs 

 as a symptom of some graver condition, such as indigestion or hog- 

 cholera. It may last but a few hours or, in more severe cases, a few 

 days. 



Treatment is unnecessary except in those cases that are due to 

 the absorption of toxic substances from the bowel. Here the ad- 

 ministration of a brisk cathartic dose of castor oil is the best method 

 of treatment. This, with a suitable change in the food, is all that is 

 necessary. Where itching is severe the official solution of lead 

 subacetate, known as Goulard's extract, may be apphed with 



benefit. 



NETTLE-RASH (URTICARIA) 



Nettle-rash, or urticaria, is a quite common disease of the hog 

 characterized by the appearance of numerous small diamond- 

 shaped elevations upon the skin. These elevations are due to the 

 pouring out of a fluid between the layers of the skin. 



Causes. — This disease is especially common in pigs. It is un- 

 doubtedly often predisposed to, if not actually caused, by the filthy 

 conditions under which hogs are kept on many farms. Irritation 

 of the skin by lice or stinging nettles is another comm.on cause for 

 the condition. An outbreak of nettle-rash not infrequently follows 

 the use of irritating dips in too strong solution. It may follow 

 sudden changes in food or the feeding of certain classes of legu- 

 minous plants. 



As a secondary or symptomatic condition, urticaria is very 

 often seen as a complication of disturbances of the stomach and 

 bowels. It is probably caused by this means more frequently than 

 from any other single factor. 



Symptoms.— In some cases the outbreak of the eruption on the 

 skin may be preceded for a day or two by a slight fever and symp- 

 toms of indigestion or constipation. As a rule, the eruption on the 

 skin occurs without any previous symptoms. The lesions are 

 noticed as small flat elevations of the skin and may be only few in 

 number or very numerous. These blotches are most frequent and 

 noticeable on the ears, sides of the neck, back of the forelegs, inside 

 of the thighs, and along the under surface of the belly. The spots 



