110 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



toms of constitutional disturbance. There is then more 

 or less extensive and painful swelling of the affected 

 quarter which begins at the teats and extends upward. 

 The milk secretion is somewhat reduced in quantity in 

 the beginning of the disease, but is otherwise unchanged. 

 Later, the secretion from the affected quarter is dimin- 

 ished ; the fat is decreased and the milk has a pale, watery 

 appearance. The inflammation may extend into the 

 gland tissue, in which case the milk will undergo the same 

 changes as in parenchymatous mastitis. 



Harmful Properties of Mastitis Milk. In mastitis 

 the secretion from the udder nearly always contains bac- 

 teria which may be harmful to man. In the catarrhal 

 form streptococci are usually present, sometimes staphy- 

 lococci or the Bacillus pyogenes. In the parenchymatous 

 form bacteria of the colon group are usually present, 

 sometimes bacilli of the paratyphus or paracolon group, 

 the enteriditis bacillus, or staphylococci. In catarrhal 

 mastitis the bacteria may be present when the milk is of 

 normal appearance and before clinical symptoms appear 

 and also after the clinical symptoms have subsided and 

 the milk has again become normal in appearance. Bac- 

 teria not only occur in the secretion from the affected 

 quarter but they may also be present in the milk from the 

 other quarters. The skin of the teats and udder is con- 

 taminated by the secretion from the diseased quarter and 

 some of this infected material can easily fall into the milk 

 pail during the drawing of milk from the other quarters. 

 Secondary infection of the milk is also likely to occur 

 when the secretion from the diseased quarter is milked 

 onto the floor, as is frequently done. The mastitis bac- 

 teria find an excellent culture media in milk and rapidly 

 multiply when the milk is kept at room temperature. 



