ANIMAL PARASITES OF CATTLE. 



527 



Fig. 21.— Portion of grass stalk bearing three encysted cercarite of 

 the common liver fluke (Faiciola hepafica). Enlarged. 



generalized edema in slaughtered cattle as a result of fluke invasion, and even in the 

 hea\iest infections of young cattle only emaciation is noticed. 



Treatment. — Medicinal treatment is unsatisfactory. The disease may be prevented 

 to a considerable extent by gi^ing animals plenty of salt, and by introducing carp. 

 frogs, and toads into infected 

 districts; these animals de- 

 stroy the young stages of the 

 parasite and feed upon the 

 snails which serve as inter- 

 mediate hosts. 



The drainage of wet 

 pastures and the avoid- 

 ance of swampy lands 

 for grazing purposes 

 are important measures 

 in the prevention of 

 fluke diseases. 



Railliet and others 

 have recently recom- 

 mended the application 

 of lime to fluky pas- 

 tures, having discov- 

 ered that very weak solutions are destructive not only to fluke 

 embryos but to snails. This application is to be made during the 

 summer months at the rateof about 500 to 1,000 pounds of lune 

 per acre. The same authors also recommend extract of male fern 

 for the treatment of fluke disease. Moussu states that the average 

 dose for cattle is 1 gram of the extract for each 10 kilograms 

 of live weight; that is, 10 grams for a young animal weighing 100 

 kilograms (about 220 pounds) up to 50 grams as a maximum for 

 large animals weighing 500 kilograms (about 1,100 poimds) or 

 more. The extract is mixed with about 5 times as much non- 

 purgative oil and the dose is administered each morning for five 

 consecutive days two hours before the animal is allowed to food after 

 having been fasted over night. The extract of male fern used should 

 have a guaranteed strength of 22 to 25 per cent of filicine and 3.5 

 per cent of filicic acid. 



TAPEWORM CYSTS OF LIVER AND OTHER VISCERA. 



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

 One of these (Multiceps multicep.<i, or Coenurus cerebralk) will be 

 further referred to in the discussion of gid (p. 528). M\ 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 when swallowed in food or water by cattle hatch out 



