526 PEOTOZOAL DISEASES. 



2. Trypanosoma Brucei causing Nagana. Transmitted by 

 Glossina flies (Tsetse flies). 



3. Trypanosoma equinum causing Mai de Caderas of South 

 America, of which the transmitting insect is uncertain. 



i. Trypanosoma equiperdum conveyed by contact, causing 

 Dourine. 



The virulence of these trypanosomes varies, which accounts for 

 the mortality of surra being less than that of nagana. 



The specific treatment of the first three consists in giving 

 arsenic, usually by intravenous injections, but in mild cases and 

 when skilled aid is wanting, arsenious acid is given in the food. 



Surra. 



DEFINITION AND CHARACTEE.— Surra {Hind, rotten) is a 

 specific fever which rims an alternating course of exacerbations 

 (paroxysms) and intervals of comparative freedom from the symp- 

 toms ; the former varying from about three to ten days according 

 to the severity of the attack ; the^ latter being somewhat shorter. 

 The alternative occurrence of these paroxysms and intermissions is 

 the chief feature of this disease. Up to recently surra was iu- 

 invariably fatal, except in favourable cases which have been treated 

 by arsenic (p. 529). 



SYMPTOMS. — pie two chief symptoms are progressive ansemia 

 (poverty of blood), and high temperature (say, 105° F., with a 

 variation of two or three degrees either way) during the exacer- 

 bations. The pulse is frequent and soft, and the breathing quick 

 and so liable to become distressed from slight exertion, that such 

 distress is often the first symptom which attracts the owner's 

 notice. The mucous membranes become pale and subsequently 

 yellow. The appetite generally is excessive and depraved, and 

 grain is usually rejected for grass, of which large quantities are 

 greedily consumed ; in fact, a ravenous appetite is almost always 

 a characteristic symptom of surra. From the first the animal is 

 dull and his movements languid. There is great loss of condition 

 and increasing weakness, and a more or less continued flow of tears 

 from the eyes. " Pain is evinced on pressure being ijiade over the 

 loins, and on each -side of the sacrum [croup]. The breath in some 

 cases is very offensive. There is continued sexual excitement in 

 both sexes. Now and then, there are dropsical swellings of the 

 legs. Occasionally, shallow ulcers appear on the gums, inside of 

 the lips and tongue. Sometimes, very superficial ones appear 



