140 SWJNB PRACTJCE 



of the liver. The cysts contain a chocolate-colored fluid and one or 

 more distomes. 



The Distoma lanceolatum produces lesions similar to those pro- 

 duced by the Distoma Americanum. The latter parasite is easily 

 distinguished from the former by its large size and its distinctive 

 shape. 



A liver in which the Distoma have developed and disappeared 

 contains cicatrices, or areas of necrotic calcareous material, evi- 

 dences of the parasitic invasion. 



Symptoms. — It is difficult to diagnose hepatic distomiasis by the 

 clinical symptoms. The history of the case, particularly the source 

 of the animal affected, should be given proper consideration. The 

 symptoms vary according to the intensity of infestation, and do 

 not appear for from one to two months after infestation. There 

 is more or less icterus, digestive derangement, unthriftiness, and 

 emaciation. The disease may terminate fatally and it may be quite 

 widespread, affecting a large percentage of swine in the Southern 

 States, particularly during wet seasons. 



Treatment.— Treatraent is of no avail. Invasion may be diminished 

 or entirely prevented by keeping swine out of pens, yards, and 

 pastures where previous infestation has occurred and by properly 

 disposing of the excrement of swine that are infested. 



Echinococcosis 



The invasion of the liver of swine with the larvse of the Tajnia 

 echinococcus is quite common. In the Old "World from one per cent 

 to seventy per cent of the swine are reported to be so infested. 



The mode of the entrance into the liver is by way of the portal 

 system, the embryo passing through the intestine into capillaries that 

 empty into radicles of the portal vein. Infestation is derived from 

 food or drink contaminated with the feces of dogs that harbor the 

 Taenia echinococcus. '^ ' J,~^~^ 



Lesions. — The liver is enlarged; the degree depending upon the 

 number of parasitic cysts it contains. Gerard observed an infested 

 swine liver that weighted 110 pounds. The surface of the liver may 

 be very irregular due to the presence of the cysts near the capsule 

 or just beneath the capsule. The cysts which vary in size from a 

 pear to a small hen's egg, are the primary lesions and may be 

 polymorphous or multilocular. The polymorphous cysts are sur- 

 rounded by a fibrous capsule inside of which the true cystic mem- 



