TRYPANOSOMIASIS 497 



Diagnosis. — ^In isolated cases with uncertain history the 

 diagnosis from the cHnical symptoms alone is often difficult. 

 In the United States where no other trypanosome disease 

 among horses is known, the microscopic determination of the 

 Trypanosoma equiperdmn is clinching. However, in our 

 climate this protozoon, which exists in the urethral or vaginal 

 discharge, plaques, and edematous swellings, is very scarce 

 and difficult to find. Negative evidence, therefore, in this 

 regard would not be convincing. Of diagnostic value are 

 the plaques, nerve symptoms (paralysis), and the marked 

 emaciation of the patient. All breeding horses and asses 

 showing these should be considered suspects. Animal 

 inoculations (dog, mouse, rabbit) may also be employed. 

 When in the primary stage dourine might be confused with 

 coital exanthema which sometimes looks strikingly like it. 

 However, this is a benign disease, heajing readily and leaving 

 behind no permanent scars and is followed by neither plaques 

 nor nerve symptoms. Traumatic lesions of the vagina from 

 excessive copulation (range mares) are characterized by 

 wounds and ecchymoses (piu'ple patches) rather than by 

 vesicles and ulcers. The mallein, guinea pig or comple- 

 ment-fixation tests suffice to differentiate between glanders 

 of the sexual organs and dourine. Paralysis due to infectious 

 anemia, forage poisoning,- etc., affects geldings as well as 

 stallions and mares. 



Course. — In northern latitudes the course is chronic; in 

 southern usually acute. In some cases the second stage, 

 beginning with the development of the cutaneous plaques, 

 follows closely the first stage. The nerve symptoms (paral- 

 yses) may not develop, however, until weeks or months 

 later. The duration of the whole attack may extend over 

 one or more years. Obviously any factor which reduces 

 the resistance of the patient (poor care, insufficient food, 

 breeding, etc.), will slxorten the duration. Exacerbations 

 and remissions during the course are common. 



Prognosis.— The prognosis is bad. Fully 50 to 80 per cent. 



of the animals attacked die. A few recover when in the 



first stage of the disease, the second stage failing to develop. 



It is doubtful whether cases in the second stage ever recover. 



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