538 



DISEASES OF CATTLE. 



^'Treatment. — Medicinal treatment is unsatisfactory. The disease 

 may be prevented to a considerable extent by giving animals plenty 

 of salt, and by introducing carp, frogs, and toads into infected dis- 

 tricts: these animals destroy the young stages of the parasite and 

 feed upon the snails which serve as intermediate hosts." 



TAI'KWORM CYSTS OF HVER AND OTHER VISCICKA. 



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

 One of these {Mulficeps multiceps, or Ccerimrus cei-ehralis) will be 

 further referred to in the discussion of gid (p. 539). All of these are 

 the intermediate stages of tapeworms which live when mature in the 

 intestines of dogs, wolves, and other canines. The eggs of the tape- 

 worms 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, mesen- 

 tery, lungs, brain, or 

 other organ, wdiere 

 they develop into 

 cysts^ A- a r i o u s 1 y 

 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 precaution against 

 infection with tapew^orms, the viscera of cattle, sheep, or hogs should 

 not be fed to dogs unless cooked. 



Hydatids {Echinococcus granulosus) form tumors (fig. 27) 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 ani- 

 mal and there is no medicinal treatment for them. Organs contain- 

 ing 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 menace to 



Fig. I'O. — Portion of grass stalk bearing three encysted 

 cercarise of the common liver fluke (Faaciola hepatica). 



