Dourine of Horses. 
11 
The test is primarily a laboratory one, in which the blood serum 
of the suspected animal is utilized to determine whether the animal 
in question has been infected with the trypanosome of dourine. The 
principles of the complement-fixation reaction are recognized the sci- 
entific world over, and its technic is extensively employed in both 
human and veterinary medicine. The Wassermann test used in the 
diagnosis of syphilis in man is a complement-fixation reaction, while 
satisfactory results are obtained in the diagnosis of glanders in horses 
and contagious abortion in cattle by complement fixation. 
The Bureau of Animal Industry will apply the test for dourine 
when samples of blood serum from animals suspected of being af- 
fected with or exposed to the disease are submitted for examination. 
As considerable skill and experience are required in properly pre- 
paring serum samples, this work should be done by a qualified veteri- 
narian. The samples, prepared according to the directions which 
follow, should be forwarded to the Chief of the Bureau of Animal 
Industry, Pathological Division, Washington, D. C, and a letter 
giving a history of the samples should be mailed to him the same 
day. 
DIRECTIONS FOR THE COLLECTION OF BLOOD SERUM FOR LABORATORY 
DIAGNOSIS. 
As the serum is the constituent of the blood which is utilized in 
applying the complement-fixation test, it is extremely important ta 
send good specimens to the laboratory in order that a conclusive and 
reliable diagnosis may be made. To obtain a good, clear specimen 
of serum the following procedure is recommended : 
Draw 4 ounces or more of blood from the jugular vein of the suspected 
animal into a dry, clean, preferably sterile, wide-mouthed bottle. The blood 
should not be collected until a steady stream flows from the cannula of the 
trocar. After the bottle is filled set it carefully to one side and allow it to 
stand for at least 30 minutes, or until complete coagulation has taken place. 
It is important to see that the blood is not disturbed until complete coagulation 
has occurred, as the serum will not separate so readily if agitated before 
coagulation takes place. The sample may then be moved if desired. The 
clotted blood should be allowed to stand for six hours longer, or until the 
clear yellow serum separates from the clot. 
When a sufficient quantity of serum has separated from the clot pour off 
from 2 to 4 drams into a small vial, being very careful not to allow the entrance 
of any red cells. If after six hours the clot fails to contract sufficiently to 
allow the yellow serum to separate from it, the process may be accomplished 
by carefully loosening the clotted blood from the sides of the bottle by means 
of a sterile ^^ire. The sample is then permitted to stand long enough for the 
clot to contract, leaving the clear yellow serum above, which should then be 
poured off. 
If the sample is to be shipped a considerable distance or in warm weather, 
the serum should be carbolized 0.5 per cent by adding 1 part of a 5 per cent 
solution of carbolic acid to 9 parts of serum. It is important not to exceed 
those proportions of carbolic acid and serum. 
The vial in which the serum is to be forwarded should be properly labeled, 
giving (a) a description of the animal from which the sample was obtained — 
whether a horse or an ass, (&) owner's name and address, and (c) name of 
person sending the sample. 
TREATMENT. 
Little benefit can be obtained from the medicinal treatment of 
dourine, nor is such treatment desirable in this country where the 
