688 VETEEINAEY HYGIENE 



of this work to speak of symptoms, it is permissible, 

 owing to the growing importance of the subject from a 

 public health point of view, to note the differential diag- 

 nosis of conditions which to the untrained eye are very 

 similar in appearance, though known to be quite distinct 

 conditions. 



In the inspection of dairy stock the udder must be 

 examined for the following diseases : 



Tubercular mastitis. 



Catarrhal mastitis, 



Acute parenchymatous 7nastitis, 



Interstitial mastitis, 



Traumatic mastitis, 



Contagious mastitis. 



Cow-pox, 



Spurious cow-pox. 



Chaps and cracks of the teat. 



Tuberculosis of the Udder. — This condition involves one 

 or more quarters, generally a posterior one. 



The earliest indication is a slow indolent swelling in the 

 depth of the gland, gradually extending and invading the 

 whole quarter or even the whole gland. There is but 

 little pain, no heat or sign of acute disturbance, the change, 

 in other words, is essentially chronic, and may take six or 

 eight weeks to accomplish, or much longer. On manipu- 

 lating such an udder the swelling is found to be large and 

 fleshy, and the inguinal lymphatics may also be found 

 enlarged. 



In the early stages the milk undergoes little or no 

 alteration, but later on it becomes scanty, and trans- 

 formed into a more or or less watery liquid. Malcolm 

 describes the early diagnosis of tuberculosis, and the effect 

 of its notification on the owner as follows : 



' When first examining such a case the mUkman generally con- 

 fidently asserts there is nothing the matter with the cow's udder, nor 

 ever has been, and further assures you the milk is all right, in proof of 

 which he at once milks the suspected quarter and asks you to inspect 



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