438 VETEEINAEY HYGIENE 



The disease does not show itself for weeks or months after 

 infection, but when the fluke has reached maturity the 

 effect on sheep is very evident ; there is great muscular 

 wasting, cedema of various parts of the body, while the 

 ansemic condition is shown by a characteristic paleness of 

 the caruncle of the eye. 



The ravages from this parasite may at times be extra- 

 ordinary. In 1830 it carried off in England two millions 

 of sheep, and has repeatedly since then caused most serious 

 losses. 



The preventive measures are simple in theory, but are 

 frequently attended by practical difficulties. The eggs 

 cannot develop on dry pastures, so that removal to a dry 

 site is naturally indicated. This may save some of the 

 sheep, but leaves the old pasture still infected. This should 

 be dried by draining, both subsoil and surface ; the 

 natural outfalls of the land must be kept in order, obstruc- 

 tions in ditches, brooks, etc., removed, and every facility 

 given for the water to run off the land. Subsoil drainage 

 is expensive, but if sheep are to be kept on the land it is 

 imperative. In the meantime pools may be filled in, and 

 wet portions of the land incapable of drainage, and probably 

 infected, should be hurdled off to prevent the sheep subse- 

 quently having access. 



If the pastures cannot be evacuated the sheep should be 

 ' penned ' on the driest portion and trough fed ; and here 

 a most important point in prevention occurs. If sheep are 

 fed on good nutritious food they may practically escape 

 infection, though neighbouring flocks may be suffering 

 severely. A liberal supply of cake and corn is required not 

 only as a preventive, but when flocks become affected it 

 assists as a curative. 



In addition there must be a liberal supply of common 

 salt with the food; the action of salt on the cercarise 

 and the immunity enjoyed by sheep on salt marshes, sug- 

 gests a top dressing of salt to the land, but experience 

 shows that the chances of bringing either lime or salt in 

 contact with the cercarise are rather remote, and that this 



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