INFLUENCE OF DISEASE UPON MILK 107 



upward, producing a hard firm area ("cake," "caked 

 udder," " cold garget "), which may eventually involve 

 the entire quarter. The newly formed connective tissue 

 subsequently contracts and causes atrophy of the gland 

 tissue and loss of function. 



In the early stages of the disease, and also throughout 

 mild cases of mucous catarrh, the milk does not show any 

 marked change at the time it is drawn from the udder. 

 Very often it contains small flakes, some of which may 

 be as small as a pin-head; they may be present only in 

 the first milk drawn, but sometimes they do not appear 

 until the middle or at the end of the milking. After the 

 milk stands for a time, or is centrifugalized, a grayish- 

 yellow sediment is deposited and a dirty-gray, clumpy 

 or granular cream layer is formed. In severe cases of 

 mucous catarrh, the secretion becomes slimy and viscid. 

 In purulent catarrh, the secretion of milk decreases 

 while the pus cells and fibrin increase and the fluid ob- 

 tained from the affected quarter gradually changes to 

 a thick, yellowish, purulent exudate or to a yellowish 

 serum containing clumps of pus and fibrin. Frequently, 

 the exudation ceases entirely and the milk secretion does 

 not return until the next lactation or not at all. The 

 chemical composition of the milk is only slightly changed 

 at the beginning of the disease, the lactose being de- 

 creased and the mineral salts, especially the sodium chlo- 

 ride, increased, while the other constituents are present 

 in the usual amount. Later, there is a greater decrease 

 in the lactose, the casein is also below normal, and the 

 fat is usually decreased, while the albumin, globulin, and 

 mineral salts are increased. Fibrin is also present. The 

 reaction of the milk is usually, but not always, alkaline. 

 The taste is salty or bitter. Cells are present in large 



