INFLUENCE OF DISEASE UPON MILK 105 



runs a subacute or chronic course; (2) parenchymatous 

 mastitis, which is purulent and acute, and which is some- 

 times accompanied by abscess formation and gangrene, 

 and (3) interstitial mastitis, which may be a simple in- 

 flammation or a phlegmonous condition. The three forms 

 differ in the type of the inflammation (acute or chronic) , 

 the part of the udder tissue affected, the effect upon the 

 milk secretion, and in the character of the bacteria con- 

 cerned. One form may be associated with another. The 

 disease is commonly called " garget " by dairymen and 

 farmers. 



1. Catarrhal Mastitis. From a hygienic standpoint, 

 catarrhal mastitis is of greatest importance because it 

 occurs more frequently than the other forms and also 

 because the milk may contain the causative bacteria be- 

 fore clinical symptoms or marked changes in the milk 

 are apparent and for a time after they have disappeared. 

 This latter circumstance has been the inspiration of 

 numerous efforts to discover a method of examining milk 

 by which this disease could be detected in its incipiency. 



Catarrhal mastitis is a mucous or purulent catarrh 

 of the mucous membrane of the teat canal, milk cistern, 

 and large milk ducts. It is frequently accompanied or 

 followed by a productive inflammation of the submucous 

 and interstitial connective tissue, in which case it often 

 terminates in atrophy of the gland tissue and loss of 

 function. It is usually caused by streptococci of varying 

 degrees of virulence; sometimes, but not often, mucous 

 catarrh occurs without the intervention of bacteria from 

 the effects of cold or overfeeding. The symptoms are 

 never pronounced. The history of the cow is of great 

 assistance in detecting incipient cases, although it is 

 sometimes difficult to obtain. A statement that the cow 



