VI DISEASES OF THE COW 107 



Pathological Investigations upon Mastitis in Cows. — We 

 owe the first definite work upon the bacteriology of this 

 condition to Nocard and MoUereau, who in 1884 isolated a 

 long chain streptococcus from the udder secretion of ten cows 

 suffering from contagious mastitis. Since that date numerous 

 investigations have been carried out by Hess and Borgeaud, 

 Kitt, G-uillebeau, Zschokke, Steiger, Groning, and others- 

 These investigators showed that this disease might be set up 

 by different organisms. Of these, apart from the chronic 

 varieties due to tuberculosis and actinomycosis, the chief 

 were streptococci, staphylococci, and varieties of Bacillus coli. 

 In all these investigations there is but little differentiation of 

 the organisms isolated, and the characters given quite fail tO' 

 separate' them from the saprophytic streptococci and staphylo- 

 cocci not only present in manure, sewage, air, etc., but also 

 in the milk drawn direct from the udders of perfectly healthy 

 cows. They are, further, in no way differentiated from the 

 disease-producing streptococci and staphylococci of man, and 

 give no assistance in determining how far the conditions 

 included under the term " mastitis " may be prejudicial to man. 

 The researches of the writer ^ for the Local Government Board 

 seem to be the only pathological investigations which deal 

 with this problem, and as the subject is of considerable practical 

 importance the following brief summary is included as far 

 as it relates to this aspect of the matter. 



Out of 3 6 cases of mastitis in cows investigated, 6 8 per cent 

 were due to streptococci, 1 6 per cent to staphylococci, 3 per cent 

 to Bacillus coli, 3 per cent (1 case) to Bacillus tuherculosis, and 

 in 10 per cent (3 cases) the results were doubtful. If the 3 

 doubtful cases are excluded, the percentage due to streptococci 

 rises to 75. A large series of tests, including the production of 

 acid in certain sugar-alcohol media, was used to differentiate 

 the streptococci. It was found that 8 per cent of the strepto- 

 cocci isolated could be grouped as forming a common type, 

 called by the writer Streptococcus mastitidis. This is a long 

 chain form growing rapidly in broth, forming a coherent 

 deposit, but leaving the upper part clear. It grows upon 

 gelatine without liquefaction, produces acid in milk, clotting 



1 Meport of tJie Medical Officer, Local Gorermnent- Pvard, ip06-7, 190'7-S, 

 1908-9. Ill 



