D oarine 765 



In the Illinois outbreak, the enlarged and pigmentless 

 clitoris constituted a noteworthy and highly diagnostic 

 symptom in the mare, persisting for at least two years after 

 all other physical signs of the malady had disappeared. 



The paresis of dourine is fairly characteristic. Accom- 

 panied by other lesions and symptoms it is pathognomonic. 

 The peculiar jerky movements in the hind limbs during pro- 

 gression, and the knuckling over at the hind pasterns are 

 rarely seen in other forms of disease. 



In addition there is the clinical history of infection by 

 coition along with the malignancy of the malady. 



The finding of the trypanosomum equiperdum in the blood 

 of the animal serves to establish definitely the diagnosis. In 

 many cases it seems to be very difficult to find the parasite. 

 Consequently this proof of the character of the disease is not 

 always readily produced. More recently the serological 

 tests have been developed and Mohler, Eichhorn and Buck 

 have obtained satisfactory results by complement-fixation, 

 using the surra trypanosome in preparing the antigen. They 

 thus secured a "group" instead of a species reaction which, 

 in the absence of other trypanosoma in this country, sufficed. 



The mortality from dourine is very great and the loss 

 amounts, upon the whole, to far more than the total value 

 of the diseased animals. When it has once become widely 

 disseminated in a breeding district, it practically suspends 

 the industry for a time because its character is so insidious 

 that it is exceedingly difficult to trace in it all its ramifica- 

 tions. The mortality among the affected animals reaches 60 

 to 80 per cent., which places it among the most fatal of 

 infectious diseases. Those which apparently recover do so 

 very slowly and the time consumed before they are again 

 fit for work is so great that their value is virtually destroyed. 

 It is a question whether animals once affected can be bred 

 again with safety, no matter how completely they may have 

 apparently recovered or how long a period may have elapsed. 



No treatment for dourine has yet been devised which is 

 economically practicable and which affords proper security 

 to the state. Recently some of the more complex arsenical 



