MASTITIS IN GENERAL 7 



stroma, the intralobular connective tissue is the most se- 

 verely affected, as it is the most loosely constructed and 

 richest in juices. These spaces become filled with exudate 

 which consists principally of leucocytes and connective-tis- 

 sue cells. In this condition the tubules become pressed 

 together and the epithelial cells undergo desquamation. 

 Part of the exudate is forced into the tubules and mixed 

 with the milk, which consequently becomes altered in its 

 composition, especially in its cell content. At the same 

 time a proliferation of the connective tissue takes place with 

 thickening of the intralobular connective tissue. Similar 

 alterations but of a lower grade take place in the remaining 

 stroma of the inflamed part. 



During the lactation period the udder is most rich in 

 juice and most sensitive, and the inflammations are there- 

 fore more severe and often malignant. The dry or alac- 

 tiferous udder, which is comparatively poor in fluid, is 

 however less sensitive toward the external influences, and 

 its inflammations are therefore milder and more benign. 



Termination. — When the irritating matter has been 

 removed by the leucocytes, inflammation recedes. The exu- 

 date is resorbed, leucocytes re-enter the blood- and lymph- 

 vessels, and cell infiltration disappears or is reduced to a 

 minimum. The intralobular connective tissue becomes 

 thinner and the tubules are again dilated and enlarged. 



The original circumference of the tubules is not attained 

 however, as the intralobular tissue has become thickened by 

 proliferation of the connective tissue, which does not com- 

 pletely reduce following a severe inflammation. As a re- 

 sult of inflammation there is usually a connective tissue 

 proliferation of varying degree which may terminate as 

 sclerosis with subsequent diminution of tubular circumfer- 

 ence or atrophy. 



Classification. — The causes of mastitis may be di- 

 vided into: (1) mastitis caused by external force; (2) 

 mastitis caused by infection, infectious mastitis. 



