138 SWINE PRACTICE 



Stephanurosis 



Liver lesions in swine due to invasion by the Stephanurus denta- 

 tuni ^arl rather cojnmon. This parasite may gain entrance into th,e 

 body either tnrough the skin or through the digestive tube, Tlie 

 lesions succeeding skin entry are usually found in and around the 

 kidney and the lesions succeeding digestive tube entry are apparently 

 confined to the liver. The life cycle of this parasite has not been 

 positively proved, but it is probable that the adult produces ova 

 while in lesions established in the animal body. The lesions in and 

 around the kidney provide an avenue of elimination of the ova by 

 way of the urinary passages, but the lesions in the liver are usually 

 of such a nature that there is little chance for the ova to escape. 

 The ova hatch outside of the animal body into embryos which after 

 moltid^ (iohtaminate food and are ingested or infest the skin and 

 pfei-mrate tfi'e tissue and establish lesions in which the young para- 

 sites develop to maturity and ovulate. 



The mode of entrance of these parasites into the liver may be by 

 way of the hepatic duct, through the portal vein, or by direct mi- 

 gration from the peritoneal cavity through ■ the liver capsule. They 

 establish inflammation accompanied by the formation of pus and 

 later necrosis of the liver tissue. The entire lesion is surrounded by 

 a rather dense white fibrous connective-tissue capsule. From one 

 to three of the parasites are found in the necrotic purulent ma- 

 terial. The content of the lesion later becomes caseous and may 

 ultimately calcify. 



No symptoms have been observed in the liver that could be at- 

 tributed to the direct action of the Stephanurus. 



Eemedial treatment is not available, but preventive measures 

 should be taken to avoid future disturbances. The exact life cycle 

 of the parasite is not known, but general sanitary regulations are 

 always in order and will no doubt be of value in preventing or at 

 least diminishing the extent of future infestations. 



Ascaridiasis 



An occasional ascarid migrates into the liver by way of the 

 hepatic duct. These parasites in this location mechanically 'ob- 

 struct the outflow of bile and also produce sufficient local irritation 

 to establish a catarrhal inflammation of the hepatic duct, the gall 

 bladder, or the bile duct. 



