512 



DISEASES OF CATTLE. 



Fig. 21.— The 

 common 

 liver fluke 

 (Fasciola 

 hepatica). 



considerable. The greenish or yellowish nodules with cheesy con- 

 tents are frequently mistaken by the inexperienced for lesions of 

 tuberculosis. 



The life histories of the various small roundworms occurring in 

 the intestines of cattle have not been worked out, but in general 

 they are very likely similar to that of the twisted stomach 

 worm as described above (p. 506). 



Treatment for intestinal roundworms. — The preventive 

 measures are similar to those recommended in the case of 

 the twisted stomach worm (p. 507). Medicinal treatment 

 is generally not very satisfactory. Powdered thymol, in 

 doses of 200 grains or more, has been recommended, but 

 it often fails to have the desired result. It is claimed by 

 one author that 2 to 3 drams of rectified empyreumatic 

 oil in a mucilaginous emulsion, followed the next morn- 

 ing with a purgative of 1 to 1£ pounds of sulphate of soda, 

 will expel the large roundworms (Ascaris vitulorum). 



Protozoa. 



A number of species of prutozoa 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 dysen- 

 tery, but as yet no cases of this disease in American 

 cattle have been reported. 



FLUKES IN LIVER AND LUNGS. 



Two species of flukes occurring in the liver and 

 lungs are known to affect cattle of the United States. 

 These parasites are flat leaf-like-worms; one of 

 them, the common liver fluke (Fasciola hepatica, 

 fig. 21), is less than an inch in length, while the 

 other, the large American fluke (Fasciola magna, 

 fig. 22), is considerably larger when full grown. In 

 their life history these flukes depend on snails as 

 intermediate hosts. At a certain stage of develop- 

 ment the young flukes leave the snails, become en- 

 cysted on stalks of grass (fig. 23), and finally may 

 be swallowed by grazing cattle. Stiles states that 

 "flukes may produce a serious, often fatal, disease, 

 more especially in younger animals." The symp- 

 toms are somewhat similar to those produced by 

 worms in the stomach. The first symptoms are generally overlooked, 

 the disease not attracting attention until the appetite is diminished ; 

 rumination becomes irregular, the animals become hidebound, and 

 the coat dull and staring. The staring coat is due to the contrac- 

 tion 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 dis- 



Fio. 22. -The large 

 American fluke 

 {Fasciola magna) . 



