EDITORIAL. 
173 
the proportion of dairy cattle affected with tuberculosis in this country, the most 
extensive being the observations made by the veterinarians of the Bureau of 
Animal Industry during the inspection and slaughter of cattle in the pleuro¬ 
pneumonia work. These observations indicated that from three to five per cent 
of the dairy cows about our large cities were affected. Some veterinarians have 
estimated that the percentage was much higher than this. It should be remem¬ 
bered, however, that these conclusions were reached by examining the lungs 
during the life of the animal, and by such hasty post-mortem examinations as 
alone were possible at the large slaughter-houses where the killing was generally 
done. \ 
Recent investigations have shown that observations made in this way are 
very unreliable, and that the percentage of affected animals so discovered must 
be entirely too low. Within the last two or three years tuberculin has been ex¬ 
tensively used to determine the existence of tuberculosis in animals, and the 
results which have been reached with it show that a large proportion of the 
tuberculous animals have been overlooked both in the examination before death 
and in the ordinary post-mortem examinations. Tuberculin has been used to a 
considerable extent in diagnosing this disease in Europe, and instead of there 
. being from five to fifteen per cent, of the dairy cows affected, as appeared from 
the older statistics, scientists are now beginning’ to talk about from forty to 
seventy-five per cent, of the cows showing the presence of this disease. 
Tuberculin has not very largely been used in the United States, and in 
most cases where it has been the herds were known to be tuberculous. For this 
reason the results of its use in this country do not furnish a reliable indication of 
the average percentage of animals affected. In the individual herds which have 
been tested from fifty to seventy per cent, of the animals have been found af¬ 
fected. Just what percentage of animals would be found affected if all the dairy 
cows of a large distict were tested with tuberculin cannot at this time be pre¬ 
dicted. In Europe as many as tw T o hundred and fifty animals have been tested 
by the same observed, and have shown from sixty to seventy-six per cent, tuber¬ 
culous. This indicates that a much larger proportion of dairy cows are affected 
than has been supposed. We should say in explanation that many of the animals 
which were shown to be tuberculous by the use of tuberculin are only very 
slightly affected, and it requires the most careful scientific examination of the 
carcass in a considerable proportion of the cases to discover the tuberculous cen¬ 
ters. Sometimes only one of the small lymphatic glands is affected, and a 
microscopic examination may be necessary to discover the effects of the disease. 
In connection with this, the report presented in this issue 
of the Review, by Dr. J. Faust, will carry its weight in re¬ 
lation to the value of tuberculin as a means of diagnosis, as 
well as an addition to the statistics establishing the relative 
percentage of cases in a given number of animals forming a 
herd. 
Practical Protection against Tuberculous Infection. 
—The holding of the expected Congress, the past and cur¬ 
rent investigations of Boards of Health, the experiments with 
