Cause.—This disease is contracted by cattle grazing on marshy lands. There are two different species of Fluke that affect the liver and lungs of cattle. They are both flat, leaf-like worms. The Common Liver Fluke is about one-half inch long, while the so-called American Fluke is somewhat larger. In their life history these Flukes depend on snails as intermediate hosts. At a certain stage of development the young Flukes live on snails. They become encysted on stalks and blades of grass which are finally swallowed by grazing cattle. This disease is most frequently seen in young cattle.

Symptoms.—The animal shows no marked signs at first, but eventually the appetite diminishes, rumination or chewing of the cud becomes irregular, the animal becomes dull, hide-bound, hair standing, the visible mucous membranes of the mouth and eyes become pale and bloodless, the eyes discharge watery fluids which ooze down the face, temperature varies from two to three degrees above normal and milk supply, if in aged cattle, remarkably reduced. In all cases there is great thirst and the animal becomes very much emaciated and refuses to eat. Swellings about the belly and breast, etc. Diarrhoea at first, alternating with constipation, but finally becomes continuous. The diseased animal succumbs to the malady in from two to six months.

Treatment.—Medical treatment is unsatisfactory. The disease will be prevented to a considerable extent by giving animals plenty of salt and in the marshes containing pools of water introduce or plant carp, frogs and toads into the infected tracts. These will destroy the young parasites and feed upon the snails which serve as their intermediate hosts. Or, prevent the cattle from grazing upon swampy marshes by fencing them out.