534 VARIOLA 



skin followed by an initial ecchymosis and occasionally by an 

 abundant exudate. The mucosa becomes opaque. The liquid 

 accumulates in vesicles followed by a pustular condition with 

 a crust or scab covering it. Upon the skin the eruption is 

 characterized by ecchymosis with marked hyperemia. The 

 histological changes have not been fully described. The des- 

 criptions published appear to be copied from those of human 

 small- pox. 



§ 422. Cow pox. In the bovine specieis the eruptions 

 are usually on the skin of the teats or udder. Other parts are 

 said to be occasionally involved. The period of incubation is 

 said to be about two days after inoculation. The first symptom 

 is a tenderness of the skin of the teats or udder, then follows 

 the appearance of small reddish spots. A few days later these 

 become vesicles, then pustules with a depressed umbilicated 

 center. These are surrounded by a pinkish or reddish areola. 

 The pustules crust over in a few days leaving a scab several 

 millimeters in diameter. Usually many of the vesicles are 

 ruptured by the hands of the milker. This often leads to scars 

 that heal with difficulty. It may happen that eruptions in all 

 the stages of development may appear on the teats at the same 

 time. 



The diagnosis of cow pox depends on the presence of 

 regular pustules with a depression, and in many cases a similar 

 exanthema on the hands of the persons occupied in the caring 

 for the affected animals. The injuries and irritations caused 

 by milking makes the diagnosis more difficult. It is possible 

 to confuse it with the exanthema of foot and mouth disease, 

 although here the nodules do not develop into pustules and 

 are at the same time larger and less regularly formed and there 

 are besides that similar vesicles even in the mouth and the 

 split of the hoof of the sick animals. The mild eruption of 

 vesicles is easy to recognize in the simultaneous affection of 

 the genitals. In rinderpest, pustules are also sometimes formed 

 on the udder, but this appearance is, in comparison with other 

 general and local symptoms, of slight importance. 



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