INFECTIOUS MASTITIS IN GENERAL 17 



Infection of the blood stream is not of long duration 

 as the blood soon deposits the infectious organisms and 

 thus purifies itself again. Infection of the blood can recur, 

 however. 



An acute fatal general blood-infection like anthrax 

 naturally cannot give rise to a local diseased process, such 

 as inflammation of the udder. A non-fatal generalized 

 blood-infection can, however, produce different infectious 

 local disease processes, such as pneumonia, pleurisy, arthri- 

 tis, nephritis, and perhaps mastitis. 



Infection of the Blood of the Udder. — The possibility 

 of one of these emboli reaching the udder is very great, since 

 both external pudic arteries are fairly large, have no im- 

 portant curves, and are incipient at the aorta. [External 

 iliac, femoral artery, external pudic or mammary artery.] 



As the aorta runs on the left side [anterior part], the 

 most direct course is to the left half of the udder which is 

 therefore most exposed to a blood-infection. It is clear, 

 however, that the situation and the time during which the 

 emboli are passing in the blood are of great importance. 

 If, for instance, a cow stands with her posterior extremity 

 inclined toward the left, the right external pudic artery is 

 the most direct course. For the emboli to reach the pos- 

 terior quarters the most direct way seems to be through 

 the external pudic arteries. 



Thus the left quarters of the udder are more exposed 

 to a blood-infection than the right, and the posterior quar- 

 ters more so than the anterior. The left posterior quarter 

 therefore is the most severely exposed. 



The small infectious emboli, if they be sufiiciently large, 

 may be caught in the capillaries or fine arterioles and at 

 these points produce a thrombus with infectious necrosis 

 and the formation of infectious metastatic foci. In other 

 cases very small emboli may be taken up and carried into 

 the loose intralobular connective tissue where the leucocytes 



