10 
Farmers' Bulletin 1U6. 
ironital symptoms alone are observable. Sooner or later, however, 
the case becomes complicated by the appearance of the systematic 
or nervous disturbances, including staggering gait, loss of flesh, and 
paralysis of the hind legs. As the symptoms become gradually in- 
tensified the animal goes down and death soon follows. 
The course of the disease is markedly influenced by the conditions 
and environment to which the animal has been subjected. Bad 
weather, exposure, insufficient food, and complicating diseases like 
influenza, distemper, or, in fact, any condition Avhich tends to lower 
the vitality of the animal, hastens the termination of the disease. 
On the other hand good care and abundant feed will prolong life 
and may even result in recovery. It is also possible, under favor- 
able conditions, that an animal may have dourine in the latent form 
for years without manifesting any symptoms and yet be a source 
of danger. 
Although now and then a case of dourine may recover, as a rule 
the disease is still present in a latent state, and the excitement of 
copulation is very likely to cause it to reappear with increased vigor. 
The outlook, therefore, is always to be considered unfavorable, and, 
in a country where a relatively small number of cases appear, tem- 
porizing methods of suppressing the disease are not warranted. 
DIAGNOSIS. 
Until recent years the diagnosis of dourine in the field rested 
solely on physical examination. As the disease is of such a nature 
that physical symptoms may not always be present, it readily is 
seen that the value of that method of diagnosis is limited, for only 
cases in which animals showed physical symptoms at the time of 
examination would be detected, and latent cases would be over- 
looked entirely. 
In 1912 the serum diagnosis of infectious diseases had been placed 
on a soimd basis in veterinary as well as hiunan medicine. The com- 
plement-fixation test used in the diagnosis of glanders in horses had 
proved to be entirely reliable, and when, in 1912, dourine was re- 
ported in Montana, steps were immediately taken to apply that test 
to dourine. After extensive experimental work a method was de- 
veloped which gave satisfactory results, and the practical use of the 
test in the control and eradication of dourine in this country and in 
Canada has demonstrated its accuracy and value. In countries where 
but one trypanosome disease exists the complement-fixation test is of 
inestimable value as a diagnostic agent, for while the reaction to the 
test is the same for all diseases caused by pathogenic trypanosomes, 
dourine is the only disease of that kind known to exist in the United 
States. By the use of the complement-fixation test it is possible to 
detect even the latent cases of dourine. Animals affected with any 
other diseases existing in the United States do not react to the test 
for dourine. 
