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Wisconsin Dairymen's Association / Fortieth annual report of the Wisconsin Dairymen's Association : held at Beloit, Wis., November, 1911. Report of the proceedings, annual address of the president, and interesting essays and discussions relating to the dairy interests
(1912)

Hastings, E. G.
Tuberculin and its uses,   pp. 97-106 PDF (2.1 MB)


Page 104

Fortieth Annual Report of the
DiscussioN.
A Member: Professor, that first chart shows that the first and the
last cow had the same temperature. Why did you condemn one cow
and not the other?
Prof. Hastings: These animals were not condemned, the whole herd
was slaughtered.  The herd was all infected and the whole herd
slaughtered. This last animal would always be looked upon as perfectly
healthy from the standpoint of the tuberculin test. She may have
been one of these animals that we call a ceased reactor, that is, where
the disease is dormant in the system and the tuberculin did not cause
any disturbance that we could detect, or she may be an animal in
which the disease is progressing at the time the test is made, and the
disturbance is not great enough to be detected.
A Member: Do you find many animals such as that one?
Prof. Hastings: It Is absolutely impossible to collect figures on that
except under such conditions as this, and yet we know they occur, for
we get them in practical work now and then. Frequently a herd is
tested and all reacting animals removed, and yet, an animal being
killed afterwards for some reason, is found to be diseased. A farmer
comes in and says, "I have had my herd tested. The test shows
thus and so. I have been told if I tested my herd and took out the
reacting animals it would all be over with, the rest would be all right."
Of course some explanation must be advanced and often it is not very
satisfactory because he has it firmly fixed in his mind that the tuber-
culin test is infallible.
A Member: Is it possible that if that cow had been given a double
dose of tuberculin it would have been more satisfactory?
Prof. Hastings: Perhaps with such a cow it would; usually when
an animal looks to be perfectly healthy we know of no reason why a
double dose should be given.
A Member: How would you account for the fact that if a man had
his cows tested and they proved all right, but a year later one should
die; then he retests the herd and finds the remaining animals perfectly
healthy.
Prof. Hastings: That first animal might have been in one or the
other of the conditions I have mentioned. An animal may have be-
come infected recently, you may test her and she does not react, and
yet within a year from that time she may get into a diseased condi-
tion.
A Member: How could the disease be introduced where the herd
has been tested and found perfectly healthy, before the retesting in a
year?
104


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