ANIMAL PAEASITES OF CATTLE. 



533 



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

 other organs, where they develop into cysts, variously known as 

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

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

 liable to be swallowed and then develop into mature tapeworms. To 

 prevent cattle from infection Avith 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 precaution against 

 infection with tapeworms, the viscera of cattle, sheep, or hogs should 

 not be fed to dogs unless cooked. 



Htdatids {Echinococcus granulosus) form tumors (fig. 27) of 

 varying size (sometimes as large as G inclies in diameter) in the 



Pio. -27. Ilyclatids i Echinocoecus granulosus) in portion of hog's liver. 



liver, lungs, and other organs. Their contents are liquid, resemljling 

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

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

 gans containino- hydatids should be destroyed by burning in order to 

 prevent their being eaten by dog;-. This is especially important, as 

 dogs infested with the tapeworm stage of this parasite are a menace 

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

 hydatids, which develop in man if the eggs of the hydatid tapev.orm 



are swallowed. 



Tiiix-KECKED BLADDER AVOEMs {Tania hiddtigcna, fig. 28) are most 

 commonly found attached to the mesentery and omentum. There is 

 no medicinal treatment. 



GiD.— Bladder worms UltiUkeps ■mdtlceps, or Cmuinis rerebrahs) , 

 which are occasionally found in the brain of cattle and cause gii, 



