TUBERCULOUS MILK 335 



and tough. Miliary tubercles appear in the walls of acini, and 

 enormous deposits of bacilli may be found in the udder. Simultane- 

 ously with these changes, the mammary lymphatic glands (pudic 

 glands) lying above the posterior region of the udder became 

 enlarged, indurated, and caseous. The disease may advance slowly or 

 with great rapidity. But finally the condition is such that the 

 glandular tissue of the udder is, as it were, smothered by the hyper- 

 trophy and fibrous transformation of the interstitial connective tissue. 

 The large excretory ducts become blocked by granulations or fibrous 

 growth outside them, or by caseous masses inside. This stage 

 inevitably leads to milk suppression (see also p. 203). 



It should not be forgotten that tuberculosis of the udder is 

 associated with tuberculosis of the internal organs. It is almost 

 invariably secondary. It may exist with mild or advanced disease 

 of the internal organs. Its diagnosis is all the more difficult 

 owing to the fact that there may be no symptoms. Generally, 

 opinion must be guided by the local condition of the udder, coupled 

 with the condition of the milk. It may occur as a slow, painless 

 growth only evident when advanced, or it may increase with extra- 

 ordinary rapidity. This latter fact makes it desirable that every 

 animal suffering from tuberculosis of however mild a character should 

 be strictly eliminated from dairy stock. The three points usually 

 emphasised for diagnosis of tuberculous udder disease are (a) 

 abnormal milk from one quarter, generally a posterior quarter ; (b) 

 some hardness, toughness, or irregularity of the udder; and (c) 

 enlargement of supra-mammary glands.* The best diagnostic of 

 general tuberculosis is the tuberculin reaction. 



Changes in Milk from a Tuberculous Udder. One of the first 

 signs of abnormality is the diminution in the yield. Previously to 

 this it is said there is an actual increase in the quantity of milk. 

 As soon as the disease begins to have effect, there is a definite decline 

 in the yield. For example, a cow which in health gave, say, fifteen 

 litres of milk, falls to one half or one quarter of that amount. The 

 milk also changes in consistence, becoming thin, watery, and serous. 

 At the same time the colour may turn to yellow, and the flocculi and 

 Hakes which occur in milk from a healthy udder are present in 

 larger size. As the yield diminishes, the consistence of the fluid 

 becomes more and more irregular, the flocculi predominating. If 

 such milk be allowed to stand in a vessel, a deposit of solid matter, 

 composed of these fragments, settles down, leaving a superficial layer 

 of thin fluid at the top. Finally, the consistence becomes sero- 

 purulent and then purulent. Hence, previously to suppression we 

 get a thick yellow purulent fluid, having an alkaline reaction, 

 coagulated casein, and diminution of lactose. As a rule, tubercle 



* See also Report of Royal Commission on Tuberculosis, 1896, part iii., pp. 41, 42. 



