THE LIVER-FLUKE OF SHEEP. 747 



it is well to use the lime to destroy snails which may have been brought 

 down from infested areas. 



If there is suspicion that a lowland is likely to give the " rot " to 

 sheep, the best plan is to not allow them to feed upon it. In seasons 

 of excessive moisture it may be impossible to keep the flocks on dry 

 pastures. Salt, as a preventive, may be used in a second way. It acts 

 injuriously upon the germs when fed to the sheep, and it also improves 

 the general health of the animal. In addition to the salt, use dry feed 

 as much as possible. The sheep should not be allowed to graze too 

 closely, for the snails, as a rule, keep near the ground. 



If all farmers would unite in carrying out the above preventive 

 measures given by Professor Thomas, the losses from a fatal disease 

 would be greatly reduced. Rabbits and hares are an obstacle to the 

 total extermination of the " rot " in sheep. 



The literature of the liver-rot in sheep is specially interesting in the 

 light of our present knowledge. Jennings, in his work on " The Horse 

 and other Live-Stock " (1866), says : " The malady is unquestionably 

 inflammation of the liver. These fluke-worms undoubtedly aggravate 

 the disease and perpetuate a state of irritability and disorganization, 

 which must necessarily undermine the strength of any animal. . . . 

 The sheep, having a little recovered from the disease, should still con- 

 tinue on the best and driest pasture on the farm, and should always 

 have salt within their reach." Youatt, in his work on sheep, in 1848 

 back of which date it is not worth while to go wrote at length 

 upon the " rot." He located the disease in the liver, and states that it 

 has existed from the earliest period of agricultural history. His de- 

 scription of a diseased sheep was full and quite accurate, but the cause 

 was unknown to him. He says, without qualification, that it is inflam- 

 mation of the liver. The full-grown fluke is too large an object to 

 escape notice in the examination of an infested liver, and therefore 

 was known to Youatt and the veterinarians of his day, but was con- 

 sidered the consequence instead of the cause of the "rot." They be- 

 lieved that the " rot " was connected in some way with the soil, it 

 being confined to wet seasons and to sheep which fed on marshy lands. 

 " It has reference to the evaporation of water, and to the presence and 

 decomposition of moist vegetable matter." In other words, the gases 

 arising from decomposing organic substances cause the " rot." Ran- 

 dall, in his " Sheep Husbandry," states that this view at that date 

 (1860) was universally received by scientific veterinarians. H. Clok, 

 V. S., in his "Diseases of Sheep" (1869), says the "rot" is analogous 

 to "fluke," and is produced by many causes, among which "grazing 

 on marshy or sour meadows " is a leading one. In speaking of the 

 fluke, he says, "The worms are found spontaneously, like all other 

 worms of the viscera, and the opinion that they are introduced into 

 the body with the food, drink, etc., must be considered erroneous." 



With the first symptoms of the liver-fluke in sheep there is a tend- 



