MORBID ANATOMY 6 1 



COCCUS from the one he has found in cases of mastitis, and also 

 in the milk of cows with healthy udders. Ward and Reed 

 produced 'mastitis in a healthy udder with the streptococcus 

 that they had isolated from a normal udder. 



The period of incubation is very short, one to three days in 

 the produced cases. 



§50. Symptoms. The first symptom is the diminution 

 in the quantity of milk, usually in but one quarter of the 

 udder. This is quickly followed by indurated foci in the 

 affected glands. The part becomes inflamed. The discharge 

 or secretion is thin, more or less colored, and contains pus 

 cells and clumps of streptococci. The lesions develop slowly, 

 and one quarter after another of the udder becomes involved. 

 Later the milk secretion is liable to stop entirely. 



§ 51. Morbid Anatomy. The tissue changes are 

 described as those of catarrhal inflammation of a mucous sur- 

 face, followed by the development of new formed tissue and 

 atrophy of the parenchymatous tissue. The gland is hard and 

 in time becomes enlarged, due to the new formed tissue. The 

 microscopic examination shows a thickened intertubular 

 tissue, and the epithelial cells more or less disintegrated and 

 sloughed from the tubular walls. The lymphatic glands and 

 other organs of the body are not involved. The lesions are 

 localized in the udder. 



The period of duration is variable, but always long. 



The prognosis is grave for the gland itself, but is rarely 

 fatal to the animal. 



§ 52. Differential Diagnosis. The diagnosis is made 

 by finding the .streptococcus in pure culture. It is to be dif- 

 ferentiated from the sporadic cases of mastitis caused primarily 

 by some injury, and the infectious mastitis caused by other 

 bacteria, largely micrococci. This can readily be done from a 

 bacteriological examination of the udder secretions. 



§ 53. Prevention. This disease is spread from the 

 infected to the non- infected largely by the hands of the 



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