362 



Most characteristic is tlie paralysis of the hind 

 legs, from which the disease takes its name. 



It runs a chronic course, two to six months. 

 In donkeys six to twelve months. There is occa- 

 sionally haemoglobinuria. 



Mice, rats, rabbits, dogs, guinea pigs, etc., 

 are susceptible. Incubation period, five to eight 

 days. Horned cattle are the most refractory. 



It is thought that the infection is transmitted 

 by a biting fly (Stomoxys calcitrans). There appears 

 to be, however, some connection between Mai de 

 caderas and a disease affecting a rodent {Hydro- 

 chaerus capybara), allied to the guinea-pig. When 

 an epidemic occurs among these, then Mai de 

 caderas breaks out among the horses (Laveran). 

 The parasite morphologically resembles T. brucei. 

 In the latter the centrosome is, however, larger. 

 In T. equinum it is so small that its existence has 

 been denied. Moreover, an animal immunized 

 against T. equinum is still susceptible to T. brucei. 



5. T. equiperdum (Fig. 81). — This trypanosome 

 is the cause of the disease among horses in Algeria 

 and India, known as Dourine. In asses the 

 symptoms are slight. In horses, and especially 

 stallions, the symptoms are much more marked. 

 It is conveyed, as far as is known, under natural 

 conditions by ' coitus ' only, and not by means of 

 flies. 



In eleven to twenty days after coitus, 

 oedematous swellings of the genitalia appear. 



In forty to fiity days characteristic ' plaques ' 

 on the skin. These are very occasionally absent, 

 as in asses, but when present are pathognomonic. 

 These 'plaques' last only one to eight days. 

 Around these there is oedema. The animals 



