PREVENTIVE MEDICINE 321 



MAMMITIS. 



All the domesticated mammals are at times affected with 

 mammitis (mastitis), but the condition is by far most frequently 

 met with in the cow. The name is given to an inflammation affect- 

 ing one or more quarters of the mammary gland. 



Bovine mammitis is produced by the invasion of the mammary 

 gland by various micro-organisms, and the cause may be acute 

 or chronic. Streptococci are most commonly associated with 

 bovine mammitis, though other organisms, e.g., staphylococci, 

 bacillus coli, &c., are occasionally responsible. Carre* has described 

 a bacillus somewhat resembling the bacillus of swine erysipelas 

 which he isolated from several cases of mammitis. Mammitis 

 of a chronic type may be produced by the tubercle bacillus or by 

 the actinomyces. The prevalence of mammitis among dairy cows 

 is shown by Savagef who, quoting from the veterinary inspector's 

 report on the examination of cows in London cowsheds, says that 

 9 per cent, of the cows at the time of inspection were suffering 

 from acute mammitis, and that 3-7 per cent, showed atrophy of one 

 or more quarters, these figures being the means of various inspec- 

 tions carried out during the year 1908. Investigators from time 

 to time have pointed out the frequency with which micro-organisms 

 are found in the milk coming from healthy udders. MathersJ 

 states that virulent haemolytic streptococci may grow and multiply 

 in the milk ducts of a cow without causing any visible changes in 

 the udder, and that milk containing them may produce cases of 

 acute tonsilitis in man. Savage investigated the frequency of the 

 occurrence of the streptococci of mammitis in quarters apparently 

 healthy. He found that in 84 per cent, of the cases in which less 

 than four quarters were affected, identical organisms were present in 

 one or more of the apparently healthy quarters. This is of some- 

 what considerable importance to the medical practitioner when one 

 considers the frequency with which the milk from apparently sound 

 quarters is mixed with the general milk. Though the risk to human 

 life is not negligible there has been, however, a great tendency in 

 some quarters in the past to exaggerate this risk. Thus on the 

 very slenderest of evidence some observers have ascribed outbreaks 

 of human sore throat to the drinking of milk from cows presenting 

 certain lesions on the teats. In the same way sore throat has been 

 attributed to the drinking of milk from cows affected with mam- 



* Revue Vet.. 1907, p. 561. 

 t Milk and Public Health, 1912. 



tJl. Inf. Dis., Vol. XIX. 

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