168 



PARASITES OF THE DOMESTIC ANIMALS 



alive after more than twenty hours. The period when salt or lime 

 should be spread on the pastures should coincide with the time when 

 the embryos of the distomes and the cercarise abound — that is, June 

 and July for the first, and August for the second." 



If it is impracticable to keep sheep from land upon which conditions 

 are favorable for the development of flukes, they should each be given 

 in the morning daily two drams of salt mixed with feed. When possible, 

 the salt may also be given in their drinking water in the proportion of 

 0.5 per cent. The salt is fatal to the ingested cercarise and tends to 

 fortify the sheep by favoring digestion and assimilation. 



Treatment. — No effective therapeutic agent for fascioliasis has as 

 yet been found. Owing to the remote location of the parasites, it is 

 hardly likely that anything could be given which would affect them. 



BiLHARZIOSIS 



This name has been given to a disease of cattle and sheep caused by 

 the blood fluke Schistosoma hovis {Bilharzia bovis; B. crassa) of the family 

 Schistosomidse. 



In this trematode (Fig. 89) there is presented the peculiarity of sep- 

 arate sexes. The female, longer and much nar- 

 rower than the male, is filiform, 18-20 mm. (^ 

 of an inch) in length, and has a buccal and ven- 

 tral sucker. The male is cylindrical, about 14 mm. 

 (3^ an inch) in length, and has two suckers. It 

 carries the female in a ventral furrow formed by 

 the two sides of the body which are broad and 

 reflected inward. Both male and female genital 

 apertures are situated immediately behind the 

 ventral sucker. 



The eggs are elongate, and at one pole termi- 

 nate in a pyriform point. They pass from the 

 host with the feces and urine, and, in the presence 

 of water, set free a ciliated embryo. 



This parasite has been found in the portal and 

 abdominal veins of cattle of tropical and sub- 

 tropical countries. The parasites themselves 

 seem to do but little injury. The eggs, however, 

 by their accumulation and sharp points, may 

 rupture the capillaries. If these are of the 

 genito-urinary system, the chief symptom is a bloody urine. Where 

 the eggs have accumulated in the capillaries of the bladder, they rup- 

 ture these and, passing through the mucosa, fall into the cavity of the 

 organ. The resulting cystitis is manifested by the hsematuria and the 



Fig. 89. — Schistosoma 

 bovis, male and female, — 

 enlarged. 



