16 
Fanners’ Bulletin 1069. 
applied in the region at the base of the tail, where the skin is soft 
and nearly hairless. The intradermal test is satisfactory also for 
the diagnosis of tuberculosis in swine and, when so used, the tuber¬ 
culin is applied into the skin of the ear near its base. 
The reaction from the intradermal test consists of a swelling at 
the point of injection and is observed from 48 to 108 hours after 
the injection. The character of the swelling varies, and a proper 
diagnosis of tuberculosis by this test can be made only by an ex¬ 
perienced person. 
THE OPHTHALMIC TEST (INTO THE EYE). 
Still another method, known as the ophthalmic, is used to some 
extent and has been found to be of considerable value in what is 
known as “check” testing: that is, it is used in connection with 
either of the previously described methods. Sometimes a tubercu¬ 
lous animal that fails to react to those tests shows evidence of the 
RELIABILITY OF THE PRINCIPAL TUBERCULIN TESTS. 
The subcutaneous test is the principal test used by 
the U. S. Bureau of Animal Industry. It consists in 
injecting, under the skin, a small quantity of tuber¬ 
culin. Carefully and conscientiously applied, with 
good judgment exercised in both its administration 
and interpretation, it is wholly effective. 
The intradermal test is recognized by the bureau 
on strictly range cattle or animals whose move¬ 
ments are difficult to control, and in area work. 
In this test the tuberculin is injected between the 
layers of the skin. 
The ophthalmic test, or so-called “eye test,” is 
not at present accepted for testing cattle for inter¬ 
state shipment, though it has value as a check test 
and is recognized for that purpose. It is applied by 
placing the ophthalmic tuberculin in one eye, using 
the other as a check. The ophthalmic test has given 
best results under farm conditions or in other cases 
where the eyes are normal. For testing cattle in 
transit or in the stockyard the test is less depend¬ 
able, owing to the fact that the eyes may be ab¬ 
normal as the result of irritation or injury from dust, 
cinders, or other results of transit. In all cases the 
tests, used either alone or in combination, should be 
applied by capable persons familiar with tuberculin 
testing. 
