124 MASTITIS OF THE COW 



cows, but in the same animal both supramammary lymph- 

 glands are the same size mider physiological conditions. 

 Thus a unilateral lymph-gland swelling is easy to deter- 

 mine, while, on the other hand, bilateral swelling is often 

 difficult. 



At first the milk is normal in appearance, later becomes 

 mixed with pus and finally, after a period of several months, 

 is purulent. In this condition it is composed of a yellow, 

 serous, thin pus containing flakes of fibrin. Milk-gangrene 

 is exceptionally rare. 



Secondary infections and abscess formation are very 

 infrequent. The contents of the abscesses when they do 

 occur is made up of yellowish-white, soft, caseous pus con- 

 taining calcareous granules. The condition is not asso- 

 ciated with fever. 



Actinomycosis attacks one quarter, but may extend to 

 other quarters. The enlargement is not great and develops 

 slowly. The corresponding lymph-gland is usually not 

 enlarged ( only in very old udder-actinomycosis is there any 

 great enlargement). 



The milk is normal in appearance for more than a 

 month, but finally becomes yellow and purulent. It is then 

 a yellow, serous, thin fluid pus containing flakes of pus. 

 Milk-gangrene is exceptionally rare. Secondary infections 

 and abscess formation are rare and the condition is not 

 accompanied by fever. 



Typical udder-infections which present no distinct swell- 

 ing of the udder are caused by streptococci. 



Typical chronic streptomycosis is a milk-infection 

 [parenchymatous mastitis]. It usually affects one quarter, 

 but may spread to the other quarters by infection. 



The milk is changed gradually. It becomes yellow, 

 thick as cream, and finally almost pulp-like in consistency, 

 and contains a great number of floating pus-cells. Milk- 

 gangrene is exceptionally rare. 



