TRYPANOSOMIASIS 495 



lymph glands become swollen. In some cases abscess of 

 the testicle with sloughing has been noted. In mares the 

 earlier symptoms may be easily overlooked (range horses). 

 There is edema of the vulva, constant erection of the clitoris, 

 and a mucopurulent discharge which soils the tail and 

 buttocks. The discharge is similar to that from the penis 

 of the male. In a short time papules, vesicles, and ulcers 

 appear on the external skin of the vulva and on the vaginal 

 mucous membrane. The ulcers, although angry looking at 

 first, heal readily, but leave behind permanent, puckered, 

 pitted scars lighter (white in skin) in color than the sur- 

 rounding skin or mucosa. The mares show estrum-like 

 symptoms (switch tail, urinate frequently). Sometimes 

 edema of the udder and ventral wall of abdomen is present. 



In some cases the above described local symptoms may be 

 mild and remain unobserved. In such cases the general 

 symptoms of the second stage of the disease are noted first 

 and the traces of the local stage then looked for. 



Secondary Stage. — ^The second stage affects stallions and 

 mares alike. Sometimes several months may elapse between 

 stages. Anything which tends to lower the resistance of 

 the patient (exposure, fatigue, breeding) may, however, 

 precipitate the second stage. In European outbreaks the 

 first symptom of the second stage is the appearance of 

 urticaria-like swelHngs (so-called plaques) of about the size 

 of a silver dollar, usually round or half round in form with 

 the centers depressed. The hairs over the swellings are 

 commonly erect. When punctured, a blood-stained serum 

 exudes from the wound. The favorite seats of the plaques 

 are the croup (near tail root), chest, wall, neck, under the 

 belly and chest. The plaques usually disappear in one to 

 eight days to be followed by a new crop. The alternate 

 appearance and disappearance of the plaques may continue 

 for several months and form a very characteristic symptom of 

 doiu-ine. In some of the American outbreaks, however, no 

 plaques were observed (overlooked?)- There is generally 

 pruritus causing the patient to rub and scratch the skin. 



Nervous Symptoms. — ^The nervous distin-bance of the 

 second stage consists largely in motor paralysis principally 



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