DISEASES OF CATTLE 369 



ease lasts from two to five months, when the most extreme cases 

 succumb. 



Most of the German cattle are said to be infested with liver 

 flukes, but even when a large number are present the nourishment 

 of the cattle is not disturbed. Thickening of the gall ducts, so that 

 a so-called Medusa's head forms on the surface of the liver 

 toward the stomach, appears in even well-nourished animals; even 

 in cases of a cirrhosis of the liver it is seldom that any effect upon 

 the cattle's health can be noticed, and so long as a portion of the 

 liver tissue about twice the size of the first remains intact, the nour- 

 ishment of the animal may be comparatively good. It is rare that 

 one sees a generalized edema in slaughtered cattle as a result of 

 fluke invasion, and even in the heaviest infections of young cattle 

 only emaciation is noticed. 



Treatment. Medicinal treatment is unsatisfactory. The dis- 

 ease may be prevented to a considerable extent by giving animals 

 plenty of salt, and by introducing carp, frogs, and toads into streams 

 and pools in infected districts ; these animals destroy the young stages 

 of the parasite and feed upon the snails which serve as intermediate 

 hosts. 



TAPEWORM CYSTS OF LIVER AND OTHER VISCERA. 



Three kinds of tapeworm cysts are found in the viscera of cattle. 

 One of these (Multiceps socialis, or Ccenurus cerebralis) will be fur- 

 ther referred to in the discussion of gid. All of these are the inter- 

 mediate stages of tapeworms which live when mature in the intestines 

 of dogs, wolves, and other canines. The eggs of the tapeworms 

 are scattered over the fields in the droppings of infested dogs or 

 wolves, and these when swallowed in food or water by cattle hatch 

 out and the embryos migrate to the liver, mesentery, lungs, brain, 

 or other organ, where they develop into cysts, variously known as 

 hydatids, bladder worms, water balls, etc. When organs of cattle 

 thus infested are eaten by dogs or wolves the cystic worms are also 

 likely to be swallowed and then develop into mature tapeworms. 

 To prevent cattle from infection with these parasites stray dogs, 

 wolves, and coyotes should be killed wherever found, and dogs too 

 valuable to kill should be kept free from tapeworms. As a pre- 

 caution against infection with tapeworms, the viscera of cattle, 

 sheep, or hogs should not be fed to dogs unless cooked. 



Hydatids (Echinococcus granulosus} form tumors of vary- 

 ing size (sometimes as large as 6 inches in diameter) in the liver, 

 lungs, and other organs. Their contents are liquid, resembling 

 water. The presence of these parasites can not be detected in the 

 living animal and there is no medicinal treatment for them. Or- 

 gans containing hydatids should be destroyed by burning in order 

 to prevent their being eaten by dogs. This is especially important, 

 as dogs infested with the tapeworm stage of this parasite are a men- 

 ace to human beings on account of the danger of infecting them 

 with hydatids, which develop in man if the eggs of the nydatid 

 tapeworm are swallowed. 



