94 
- Parasites of Cattle and Sheep. 
The mature fluke is flat and about an inch long. While in 
the liver, the female deposits her eggs, which are carried out 
and distributed over the pasture with the dung. If the fresh 
water snail (. Limncea truncatula) is available the embryo 
enters it. 
Symptoms . — It has often been stated that in the early 
stages of the disease the infested sheep puts on flesh and 
appears to do exceptionally well, and that this is due to 
increased flow of bile, resulting from irritation of the young 
fluke creeping up the bile ducts. This improvement in 
condition may, and probably does, depend on the fact that 
situations in which the sheep takes in the flukes are most 
commonly old pastures, which at the time are full of grass 
owing to the wet weather or flooding which is so favourable 
to the development of fluke embryos. Soon after this reputed 
improvement, the sheep loses condition and becomes anaemic, 
as evidenced by paleness of the membrane of the eye and 
gums. After a while, the appetite is lost, emaciation is notice- 
able, there are dropsical swellings, especially under or between 
the jaws, the abdomen enlarges, the spine becomes prominent 
(razor back), and the appetite is affected. Should the 
symptoms subside, recovery will be slow. 
Post-mortem examination shows changes almost entirely 
confined to the liver and the blood. The walls of the bile 
duct are thickened throughout, giving to the organ a certain 
hardness to the touch, which may be extreme, owing to 
deposition of lime salts. Flukes may be found in the large 
ducts, or if the organ is cut through and squeezed, they will 
appear on the cut surface. 
Prevention . — As there are no known means of expelling 
the flukes from the bile ducts, the importance of preventive 
measures is paramount. Moisture is essential to the develop- 
ment of the free-swimming embryo and of the snail (. Limncea 
truncatula) into which it bores. Without the snail, the 
embryo can advance no further. The surest and probably the 
easiest way to prevent liver rot is to prevent the existence of 
this and all other fresh water snails. The snail will not live 
without water and that water must be fresh. All means should 
therefore be taken to prevent water standing in ditches, pools, 
&c., while the application of salt to infested pastures (5 to 10 
cwt. per acre), in the autumn, helps to establish conditions 
unfavourable to its life. Liming of pastures has been freely 
advocated, but it is difficult to see how this can be of 
substantial service. Livers containing flukes should be well 
boiled if to be used for dogs, &c., but under all circumstances 
the flukes it may contain should be destroyed. Sheep from 
affected flocks should not be brought on to a place. When 
