Occurrence, Etiology, Symptoms. 361 



Among the horses of the Prussian Army, from 1904-1906, 48, 113 and 3 cases 

 were observed, and in 1908, 16 cases were found. 



Etiology. The virus is apparently contained in the nodules 

 and pustules on the mucous membrane and skin, and becomes 

 mixed with their contents, also with the secretions of the mucous 

 membrane, as well as with the saliva of the infected animals. 

 Horses may be infected by rubbing the infectious saliva into 

 the mucous membrane of the mouth or nose, or by superficial 

 scariiication of the skin; sometimes transmission is also suc- 

 cessful to cattle, sheep, hogs and chickens (Eggeling & Ellen- 

 berger, Friedberger). Man is also susceptible to a certain 

 degree, as febrile dermatitis with pustular formation with sali- 

 vation and difficulty in swallowing, has been observed on the 

 hands and on the face of persons who were employed around 

 infected animals (Greswell, Ellenberger, Schultz). Under nat- 

 ural conditions the disease occurs only among horses. 



The natural infection is as a rule transmitted by the saliva 

 and the nasal discharge from affected animals, which reaches 

 the mucous membrane of healthy animals with the drinking 

 w^ater, food, straw, or from the hands of the attendants. The 

 fact that the disease does not spread over large territories, but 

 disappears of itself in a relatively short time, indicates that the 

 virulence of the virus is attenuated during its passage from 

 animal to animal, or that the virus is soon destroyed in the outer 

 world. 



Young horses are much more susceptible than older ani- 

 mals, but variations in the susceptibility are also noted in the 

 individual animals. In large stables most horses usually become 

 successively affected, some however remain healthy. Horses 

 which recover from the disease resist a new infection for a 

 long time, the extent of which is not known. 



Symptoms. After a period of incubation which in artificial 

 inoculation is 3 to 5, and in natural infections 8 days, the disease 

 commences with a moderate fever, which is manifested by a rise 

 in temperature of from 1 to 11/2 degrees, as well as a moderate 

 acceleration of the pulse and debility. The animals take their 

 feed more slowly, masticate cautiously, and enjoy playing with 

 the lips in the water offered them. At intervals they keep the 

 mouth closed, when from its corners pure saliva drips out in 

 long threads. 



The mucous membrane of the mouth at first has a higher 

 temperature; it is painful and reddened in spots; soon the red 

 spots coalesce, and at the same time hemp-seed to lentil, or even 

 pea-size hard nodules develop on the inner surface of the lips, 

 on the gums lying opposite, and also on the intervening folds, 

 further in the vicinity of the f renum of the tongue, in the vicinity 

 of the commissures of the mouth, and on the inner surface of 

 the cheeks. Fresh nodules continue to develop for 2 to 3 days, 

 until they appear in great numliers upon these places and 



