SELECTED ARTICLE

                             STUDIES ON BOVINE MASTITIS

          XI.—FURTHER OBSERVATIONS ON THE CONTROL OF
                     CHRONIC STREPTOCOCCUS MASTITIS

                                                      BY

         A. W. STABLEFORTH, S. J. EDWARDS AND F. C. MINETT,

  Research Institute in Animal Pathology, Royal Veterinary College, London.

[Reprinted from " The Journal of Comparative Pathology and Therapeutics,"
                               Vol. XLVIII. Part 4. December, 1935.]

IN 1933 we gave an account of a herd from which chronic streptococcus mastitis
due to Str. agalactiæ had been eradicated by the segregation and eventual sale
of infected cows. This confirmed the generally accepted belief that this disease
is strictly contagious and that, therefore, it should be possible to control it by the
simple procedure of avoiding direct transmission during milking. At that time
similar control measures were also being carried out in six other herds, viz., Herds
A, C, I, J, K and L and the purpose of this report is to detail the results of
this work.

It is evident from the literature on the subject that laboratories concerned
with mastitis are now giving more attention to control of the disease by segregation,
with or without treatment of infected cows. Vaccines, autogenous or other, have
gradually fallen into disrepute because, although some authors believe they re-
duce the more obvious manifestations of the disease, they do little or nothing to
diminish the number of infected udders or to prevent the spread of the disease.
In accordance with this view, many workers who have tried vaccination, e.g.,
Seelemann, Plastridge, Anderson, White and Rettger, have replaced it by segre-
gation methods, whilst in Germany a voluntary state-assisted scheme of control
based on segregation of infected cows and their treatment with " entozon " was
initiated in April, 1934.

Among the more recent efforts at vaccination or eradication reference maybe
made to the following.

Seddon and Rose [1934] employed killed vaccines in a herd of about 100 cows
over a period of five years. No controls were kept. The amount of obvious mastitis
was reduced both in respect of numbers of cases and severity, but the incidence of
streptococcus infection was unaltered. Similar findings were reported by Krage
and Gipmann in 1931.

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