Symptoms. 



321 



round, on the teats they are oval in the direction of the long 

 axis of the teat, and they are surrounded by a red zone of 

 1 to 2 mm. width. Toward the eighth to eleventh day they usu- 

 ally become ripe, and then they show in their center a well- 

 defined depression ("Delle" navel), which however may some- 

 times be absent. Later the contents of the vesicles turn puru- 

 lent, and dry to scabs (Fig. 56). After the scabs drop off the 

 underlying skin is at first pale red and swollen, later however it 

 shows shallow, white, cicatricial depressions in the affected parts. 

 According to the severity of the case one, two or numerous, 

 but only exceptionally more than 15 to 20, vesicles develop. They 

 do not appear at the same time, but mostly at intervals of a 

 few days, thus between the appearance of the first and the last 



Fig. 56. Cow pox on the udder. ( After Fregee. ) 



vesicle 4 to 6 and sometimes even 14 days may elapse, as may 

 be seen by the varying stages of development of the vesicles. 

 Frequently the later vesicles are smaller than the early ones. 

 Outside influences, especially traumatic, have frequently an 

 unfavorable effect on the otherwise mild course of the disease. 

 During milking the vesicles may easily rupture before they 

 obtain their full ripeness. On such an exposed, readily bleed- 

 ing wound the scab formation cannot take place on account of 

 the repeated handling, and in the meantime the regeneration of 

 the epithelium does not take place in the usual way, but on 

 the contrary the inflammation of the surrounding connective 

 tissue is aggravated from the frequent irritation of the wound. 



Vol. 1—21 



