ANIMAL PARASITES OF CATTLE. 



531 



Treatment for intestinal roundworms. — The preventive measures 

 are similar to those recommended in the case of the twisted stomach 

 worm (p. 526). Medical treatment is generally not very satisfac- 

 tory. Powdered thymol, in doses of 200 grains or more, has been 

 recommended, but it often fails to have the desired result. It is 

 asserted by one author that 2 or 3 drams of rectified empyreumatic 

 oil in a mucilaginous emulsion, followed the next morning with a 

 purgative of 1 to 1| pounds of sulphate of soda, will expel the large 

 roundworms {Ascarls vitulorum). 



PROTOZOA. 



A number of species of protozoa have been reported as parasites of 

 the intestines of cattle. To one species has been attributed a serious 

 disease of cattle in Switzerland known as red dysentery, but so far 

 no cases of this disease in American cattle have been reported. 



Fig. 24. — The com- 

 mon liver fluke 

 (Fasciola hepat- 

 ica). 



FLUKES IN LIVER AND LUNGS. 



Two species of flukes occurring in the liver and lungs are known 

 to affect cattle in the United States. These parasites are flat, leaf- 

 like worms; one of them, the common liver fluke 

 {Fasciola hepatica, fig. 24), is less than an inch in 

 length, while the other, the large American fluke 

 (Fasciola magna, fig. 25) , is considerably larger when 

 full grown. In their life history these flukes depend 

 on snails as intermediate hosts. At a certain stage 

 of development the young flukes leave the snails, 

 become encysted on stalks of grass (fig, 26), or fall into drinking 

 water, and finally may be swallowed by cattle. Stiles writes as 

 follows : 



Flukes may produce a serious, often fatal, disease, more especially in younger 

 animals. The symptoms are somewhat similar to those produced by worms in 



tlie stomach. The first symp- 



'"•.^'y&l^^^ "^^Jf^si^ toms are generally overlooked, 



the disease not attracting at- 

 tention until the appetite is 

 diminished ; rumination be- 

 comes irregular, the animals 

 become hidebound, and the 

 coat dull and staring. The 

 staring coat is due to the 

 contraction of the muscles of 

 the hair follicles. The visible mucous membranes become pale, eyes become 

 dull, there is running at the eyes, and the animal gradually becomes emaciated. 

 As the disease advances the milk supply is lessened, fever appears, there is 

 generally great thirst, but the appetite almost ceases ; edematous swellings 

 appear on the belly, breast, etc. ; diarrhea at first alternates with constipation. 



Fig. 25. — The large American fluke (Fasciola magna). 



