532 



DISEASES OF CATTLE. 



but finally becomes continuous. The disease lusts 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 dis- 

 turbed. 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 fist remains intact, the nourish- 

 ment 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 disease may be 

 ]irevented to a considerable extent by giving animals plenty of salt, and by 



introducing carp, frogs, and 

 toads into infected dis- 

 tricts ; these animals de- 

 stroy the young stages of 

 the parasite and feed upon 

 the snails which serve as 

 intermediate 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 discovered 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 rate of about 500 to 1,000 pounds 

 of lime per acre. The same authors also recommend for the treat- 

 ment of fluke disease extract of male fern in doses of 5 gi-ams to 

 each 30 kilograms of body weight. Apparently, however, satisfac- 

 tory results from this treatment are not always obtained. 



TAPEWORM CYSTS OF LIVER AND OTHER VISCERA. 



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

 One of these (Multiceps muUiceps, or Ccermrus cerebralis) will be 

 further referred to in the discussion of gid (p. 533). All 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 lire scattered over the fields in the droppings of infested dogs 

 or wolves, niul when swallowed in food or water by cattle hatch out 



Fig. 26. — Portion of grass stalk bearing three encysted 

 cercarise of the common liver flulce (Fasciola hepatica) . 

 Enlarged. 



