122 MASTITIS OF THE COW 



may suspect staphylomycosis. The more common sporadic 

 cases may be any of the three infections. 



The chrome genuine udder-infections may be divided 

 into two groups: 



1. Atypical chronic udder-infections which begin as 

 severe acute infections and then become chronic. 



2. Typical chronic udder-infections which are not 

 noticeable in the beginning. 



Atypical udder-infections are undoubtedly streptomy- 

 cosis. 



The atypical chronic streptomycosis begins with all the 

 symptoms of a severe acute udder-infection (milk-infec- 

 tion) [parenchymatous mastitis] with alterations of the 

 milk, swelling of the udder and fever. The fever subsides, 

 but the alterations of the milk and swelling of the udder 

 remain about a month. The udder finally becomes as 

 hard as stone, through sclerosis, and may manifest nodular 

 foci which, when incised, present pus and probably firm 

 necrotic sequesters in an abscess cavity surrounded by a 

 smooth connective-tissue wall. 



Pyobacillosis and tuberculosis may run a course like an 

 atypical chronic udder-infection when they enter an acute 

 udder-infection as complicating secondary infections. In 

 these cases the acute infection is simply displaced by a 

 different chronic infection. 



Typical chrome udder-infections are not noticeable in 

 the beginning, but gradually produce alterations in the milk 

 and udder. 



When a blood-vessel is injured the milk may be slightly 

 tinged with blood. The lesions of the udder are but slightly 

 or not at all painful. 



These infections may be divided into two sub-groups: 

 (a) those which cause a distinct swelling of the udder; 

 {b) those in which no distinct swelling is present. 



The typical chronic udder-infections which cause a dis- 



