Nov. io, 1913 
Diagnosis of Dourine 
101 
although our more recent experience proves that the organism may occa¬ 
sionally be found in the serous exudate of the plaques and also in the 
fluid of the edematous swellings of the genital organs in the stallions 
as well as in the mares. 
Of course, this procedure of diagnosis can be attempted only when 
the disease occurs in farming localities where the animals can be readily 
observed and examined as desired. On the other hand, in the present 
outbreak in Montana and adjoining States the conditions make the 
diagnosis by the demonstration of trypanosomes impossible, and, like¬ 
wise, animal inoculations can not be satisfactorily utilized for this purpose. 
Horses in that locality are bred under range conditions; they run wild 
and a round-up takes place only once a year. The difficulty of an exami¬ 
nation, even clinically, of such animals is obvious, since they have 
not been broken to the halter and are troublesome to handle. 
Our experience with the disease in Montana showed that only a limited 
number of animals were clinically affected. Nevertheless, the associa¬ 
tion of all the animals without any restriction in the breeding periods 
indicated that a larger number of animals would be found infected, 
which, as a matter of fact, has been proved by subsequent tests, as 
hereinafter shown. 
Owing to the fact that until the last few years the eradication of 
dourine in this country was supposed to have been complete, the disease 
has received only slight attention as compared with other menacing 
diseases of our domesticated animals. It was not until the outbreak 
in the State of Iowa in 1911 that the necessity for devising a method of 
diagnosing this infection began to be fully realized. The value of being 
able to detect the latent and to verify the clinical cases became apparent. 
Otherwise, the necessity existed of maintaining a long-continued quar¬ 
antine in those sections of the country where cases have been discovered. 
While little difficulty has been experienced in recognizing the advanced 
cases, a clinical examination alone naturally permitted many infected 
animals to escape detection, only to facilitate the further spread of the 
disease until the appearance of symptoms made the diagnosis unques¬ 
tionable. 
Inasmuch as the complement-fixation method of diagnosis has been 
employed with gratifying results in connection with numerous other 
diseases, the possibility of applying this method to dourine naturally 
suggested itself, and steps were therefore taken to determine the feasi¬ 
bility of its application to this disease. 
It was very early discovered that the problem of preparing a satis¬ 
factory antigen would offer considerable difficulty. Efforts were pri¬ 
marily directed toward utilizing for this purpose the different organs of 
those horses that had succumbed to the disease. Several of the clinical 
cases were shipped from Iowa to the Bethesda Experiment Station 
during the outbreak referred to, in order that a more complete observa- 
