Etiology. Symptoms. 841 



heat, and in another following upon a vaginal catarrh, while 

 Houllier & Delannoy saw such cases follow the stoppage of the 

 milk secretion, especially in market cows. Finally nettlerash 

 may appear some hours after squeezing out the warbles in 

 cattle affected with larvae of the gadfly (Strose). All these cases 

 probably represent phenomena of hypersusceptibility to the 

 absorption of heterogenous proteid matter, which gains access 

 to the blood from the intestine in digestive disorders, or from 

 other organs. Probably the homogenous proteid which has ex- 

 uded into holloAV organs acts like heterogenous proteid after 

 undergoing certain changes. 



Toxins of specific microorganisms are evidently of im- 

 portance if the affection arises in the course of infectious dis- 

 eases: for instance, in dourine (see Vol. I), in swine erysipelas, 

 the mild form of which runs a course similar to nettlerash 

 (Backsteinblattern) (see Vol. I), in purpura in which the edem- 

 atous swellings sometimes develop from nettlerash; further, in 

 influenza and in strangles where nettlerash is noticed rather 

 frequently, especially in the convalescent stage ; finally, it occurs 

 in many animals after injections of mallein or tuberculin. 



Both the primary as well as the secondary urticaria occur 

 most frequently in horses, although cattle and swine may also 

 be affected and more rarely dogs. 



Symptoms. Nettlerash is sometimes preceded by indiges- 

 tion, debility and a fever temperature (nettle fever, urticaria 

 febrilis, febris urticata). Eggeling observed fever in cows up 

 to 40.9' C, while feverish s^^nptoms were observed by Perkuhn 

 and Karpe in horses at the onset of the disease. The eruption 

 occurs, however, mostly without these prodromal s^inptoms. 

 Prominent swellings from pea to almond in size, hard, flat or 

 half round, appear here and there on the skin, over which the 

 hair appears somewhat ruffled. The swellings on the skin pre- 

 serve these characteristics until they disappear, or they 

 broaden on the surface and sink in at the center becoming- 

 ring shaped (IT. annularis) ; by contact Avith one another sev- 

 eral of these rings may form wave-like figures (U. gyrata s. 

 figurata; seen especially well in horses suffering from dourine). 

 On the skin of swine the swellings are at first of a reddish 

 color, later they increase in size and fade in the middle (U. 

 porcellanea), the progressing edge forming a red seam. If 

 the affection is caused by the direct action of acrid substances, 

 there exists in most cases a more or less intense itching, which 

 otherwise is absent as a rule. 



The development of the eruption may take place so quickly 

 that within 5 to 30 minutes almost the whole surface of the 

 body may be covered with elevations (Mecke, Jost). They last 

 generally a very short time, a few hours or 1 to 2 days (in 

 swine 4 to 6 days) and disappear without leaving a trace, after 

 the swellings have become flattened (U. ephemera) ; occasion- 



