510 DISEASES OE CATTLE. 



numerous, these parasites cause a thickening of the stomach wall 

 and disturb its digestive functions. The symptoms caused by this 

 parasite are very similar to those produced by the twisted stomach 

 worm. The life history of the encysted stomach worm is not known 

 in detail, but it is undoubtedly very much the same as that of the 

 twisted stomach worm. The same measures as recommended above 

 for preventing infection with the twisted stomach worm should be 

 employed. Medicinal treatment is of little use, owing to the pro- 

 tected position in which the parasite occurs. 



INTESTINAL PARASITES. 



Tapeworms. "■ 



Two species of tapeworms (fig. 20) are known to occur in the small 

 intestine of American cattle. They sometimes grow to a length of 

 several yards and to a breadth of three-fourths of an inch. Small 



portions of tapeworms, consisting of 

 ' &■■")&(} fo-O "'i * one or more segments, are occasionally 

 0^^[6^^^^0^ M seen in the droppings of infested cattle. 



® -Q® ' "0^W : fe^S The life history is not known > bnt the 



Q %r, Q %> G <Q& ^ infectious stage is undoubtedly taken 



Q %**& & /^^Ic* ^' in wittl tlie food or water > infection 



;%? e ^^£<ii^ ; '^% being spread by the eggs of the para- 



Jjffi & - - 8ite contained in the feces of infested 



to® • '''%%'$§{& ^ '°S animals. The eggs perhaps are swal- 



(£> Q Q && m &* lowed by some small creature (an in- 



^^^S^0S:Mv : m^^i sec t ; worm, or snail) which acts as an 



Fia. w.-Piece of lining of fourth stom- intermediate host, and which when 



ach, showing cysts of the encysted . ,, . , .. 



stomach worm ( ostertagia ostertagi) . s wallowed accidentally by a cow while 



grazing or drinking carries with it into 

 the cow's stomach the infectious stage of the tapeworm. 



Adult cattle do not seem to suffer much from infestation with 

 tapeworms, but in calves these parasites may cause scouring and 

 emaciation. 



Treatment for tapeworms. — Medical treatment for tapeworms in 

 cattle is usually unsatisfactory, but the bluestone treatment used for 

 stomach worms and mentioned above (p. 509) may be tried. Arsenic 

 in doses of 1£ to 3 grains has been claimed to give good results in the 

 treatment of calves for tapeworms. 



Roundworms. 



A large roundworm (Ascaris vitulorum) measuring 6 to 12 inches 

 in length sometimes found in the intestine of cattle, especially calves, 



o Bulletin 4 of the Bureau of Animal Industry contains a technical discussion of 

 the tapeworms of cattle, sheep, and allied animals. Bulletin 19 of the same 

 bureau deals with these and other internal parasites with particular reference to 

 meat inspection. 



