Of all the methods for the treatment of Contagious Bovine Mastitis evolved to date, udder infusion with bactericidal substances appears to be the one which promises the greatest success. The method originated in Europe, and particularly in Germany and Switzerland, in which countries it has been given very extensive trials. More recently the method was used in Great Britain and a fair degree of success attained. The results of the experiments in Great Britain are of most interest to this country as our methods of diagnosing the conditions are based on the ones used there, and are more exacting than those generally employed on the Continent. Furthermore, the serological differentiation of the causal organism, Str. agalactiae, into types and sub-types, which is used as a routine in Great Britain and here, allows one to distinguish between persistence of the original infection and reinfection.
The materials which have been used in this work are the dye-stuffs, Trypaflavine and Acriflavine and a proprietary substance named "Entozon," which has the virtue of being less irritant than the dye-stuffs. In the experiments conducted at this station, only "Entozon" has been used up to the present, and therefore this article will be confined in the main to Entown and its use. In milking cows, a solution of 1/1250 is employed. The udder is milked out thoroughly and the teat orifices wiped with a little alcohol. A sterilised teat siphon is inserted and about 100 ml. of the solution allowed to infuse into the quarter under gravity pressure only. This quantity is immediately milked out and then the teat siphon is reinserted and the Entozon solution allowed to infuse into the quarter until a tensity exists comparable to the normal tensity of the udder prior to milking. A little experience is necessary in this operation, as the cow frequently becomes restless if the tension is too severe. The solution is allowed to remain in the quarter for five minutes, and it is then thoroughly milked out and should be milked out as frequently as possible during the 24 hours following treatment. Little disturbance of the milk supply occurs and, although the milk is discoloured and yields an increased deposit for several days, it rapidly returns to normal. The treatment or dry cows differs only in that the Entozon is used at a strength of 1/500 and the infused solution is allowed to remain in the quarter for 24 hours before being milked out.
The dye-stuffs Trypaflavine and Acriflavine, are used in a similar manner except that a much higher dilution is employed. In the experiment conducted at this station, milk samples from each quarter of all cows were examined bacteriologically. Those found infected were subjected to the treatment and were required to pass two bacteriological examinations at weekly intervals before being permitted to join the clean herd. The investigation is as yet incomplete, and the results given must be regarded only as progress results.
Nineteen infected cows in milk have been treated, and eight were freed from infection alter one treatment, five after two treatments, one after three treatments, and one after four treatments. Two cows were severely fibrosed cases of long standing in which treatment was ineffective, and in the remaining two cows the disease progressed steadily in spite of treatment.
During the progress of the work, several interesting reflections were revealed. Firstly, that for practical purposes, it is desirable to treat all quarters of any cow which has been found to be infected in one or more quarters, particularly if one bacteriological examination has been relied upon to detect infection, because after freeing the quarter from infection the organism might be detected in another quarter which had passed the initial examination. Secondly, one cannot expect to cure badly fibrosed quarters, and as cows possessing such quarters are a poor economic proposition in any case, it would be wise to eliminate them from the herd. Thirdly, it appears that some first-calf heifers are infected before being brought into the dairy. This point has been demonstrated previously in the United States of America, and while no evidence is available as to when and where the infection takes place, it shows that the source of infection cannot be confined solely to the dairy. Lastly, it is apparent that some infected cows are more resistant to the treatment than the avenge cow. Such cows are not necessarily clinically infected nor do they necessarily show increased deposits in their samples of milk. This latter point was exemplified in the case of a first-calf heifer which was found to be infected in all four quarters when examined as soon as the colostrum had disappeared from the milk. In spite of three treatments, the organism persisted in all quarters and a rapid progressive fibrosis of the udder was in evidence although no deposit of an inflammatory nature was demonstrable at any examination of her milk.
While it is too early in the course of our investigations to make a definite recommendation for the use of these substances, the results obtained so far are considered sufficiently encouraging to extend our experiments with Entozon to a much larger herd and to test the value of the dye-stuffs. Furthermore, it is obvious that should this method of treatment come into wide use, it would not be possible with the present facilities to make bacteriological examination available to all. Therefore, some practical plan of applying the treatment on a large scale will have to be formulated. This might be along the following lines, although at the moment it must be considered as sheer conjecture.
(a) All severely fibrosed cases to be eliminated from the herd.
(b) All cows remaining in the herd, whether dry or in milk, to be treated twice.
From the work quoted above, it will be realised that such a procedure will not eliminate all infection from the herd but it would do a very great deal toward limiting the seventy of the disease in any herd and would reduce the chances of any individual cow in that herd becoming infected.
In conclusion, it is desired to emphasise that the adoption of therapeutic measures cannot replace the value of hygienic methods in combating the spread of disease, and a high standard of cleanliness should be maintained always.