100 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



but it is occasionally enzootic, especially when musty 

 or mouldy straw is used for bedding. It is most fre- 

 quently seen in fresh cows, after they have been put on 

 full feed, and it is probably for this reason that the fu- 

 runcles are spoken of as feed boils. Firm, painful, nodu- 

 lar swellings, varying in size from a pea to a walnut, 

 appear in the subcutaneous tissue of the udder. In 

 seven or eight days a dark area of puriform softening 

 develops in the centre of each individual swelling, which 

 subsequently ruptures at this point and discharges its 

 contents of pus mixed with shreds of tissue. This dark 

 patch, or the scab of dried blood which subsequently 

 forms at the point of rupture, has given the process the 

 popular name of black scab in some sections. The milk 

 secretion is not affected, but the milk may be contami- 

 nated secondarily with the purulent discharge. 



ANTHRAX 



The question of using the milk from a cow affected 

 with anthrax does not often arise in practice because, 

 as a rule, the milk secretion ceases suddenly with the onset 

 of the fever, while in those cases in which it continues 

 it is reduced to a small quantity and is very much changed 

 in appearance. It is more yellowish than normal, slimy, 

 sometimes bloody, with a bitter taste, and after standing 

 undisturbed for a few hours separates into a layer of cream 

 and of serum. Anthrax bacilli are excreted through the 

 udder only in the advanced stages of the disease, after they 

 have invaded the blood stream and when the udder is 

 affected. But the chances of milk becoming infected 

 secondarily are very great. The bloody discharges and 

 the manure from infected animals contain the anthrax 



