462 MILK 



suffers the loss of solid constituents, except the ash, which remains 

 constant or even increases. The disease is highly infectious for 

 cattle. Infection of man takes place by consumption of infected 

 milk or sometimes by contact. In man vesicles form on the 

 mucous membrane of the mouth, sometimes on the hands, ears, 

 breast, and arms. Temperature accompanies the other symp- 

 toms. The digestive tract is affected, and vomiting and diarrhea 

 follow. Children are very susceptible to the disease, but the 

 disease is rarely fatal. Efficient pasteurization of the milk de- 

 stroys the infection. 



Mastitis, or garget, is a disease of the udder which is very 

 wide-spread, much more so than is generally assumed. It has 

 been stated by some authorities that there is probably no herd 

 that is entirely free from mastitis. The disease assumes either a 

 chronic or an acute form. Symptoms in the chronic form may be 

 sufficiently insignificant to escape attention for some time. There 

 are intermediate stages between the two forms, so it is not sur- 

 prising that cases of mastitis are actually found in herds which 

 have been subjected to a painstaking examination and which have 

 been thought to be free from the disease. 



When cows suffer from mastitis the milk undergoes material 

 changes in appearance, taste, and composition. These changes 

 are more pronounced as the disease becomes more acute. Dur- 

 ing chronic attacks or at the commencement of the acute stage of 

 the disease, the changes are slight and sometimes difficult to detect. 

 In well-developed, acute cases parts of the blood pass into the 

 milk and the number of body cells becomes enormously increased. 

 However, there is no definite relation established between the 

 number of body cells and pathologic conditions. If the disease 

 is acute the udder enlarges, the temperature rises, and the milk 

 becomes stringy, bloody, or yellow. During chronic attacks the 

 changes progress slowly. At first the milk seems normal, but 

 later becomes thick, slimy, and may contain red blood-cells. 

 On standing, a yellowish sediment appears. Instead of becom- 

 ing thick and slimy, the milk may appear thin, as though watered. 

 The taste turns bitter. It is a relatively easy matter for the milker 

 to detect these changes in the milk if he is attentive. Close ques- 

 tioning of milkers by a veterinarian may give much aid in locating 

 affected animals. When the milk becomes thin a laboratory test 

 may give the impression that the milk has been watered. This 

 is an additional argument to show that single tests should not be 

 relied upon to judge the quality of milk. 



The following are the most common changes which may arouse 

 suspicion: The fat content may become abnormally high or low; 

 the lactose may diminish; the total solids and plasma solids may 



