CONGESTION OF THE LIVER 231 



CONGESTION OF THE LIVER. 



Two forms of this disease are distinguished: (a) Active, 

 and (b) passive. 



Active Congestion.— Definition.— An engorgement of the 

 liver with blood resulting from an increased circulation 

 through the portal vein or hepatic artery. 



Etiology.— There are a number of etiological factors in 

 active congestion of the liver: (a) During the process of 

 digestion there is a physiological increase in the amount of 

 blood carried to the liver by the portal vein. This, however, 

 usually subsides after digestion is completed. In small 

 animals, owing to the great variation in the amount and 

 quality of food taken, and the fact that the food often 

 contains irritating material, toxins, ptomaines, etc., all of 

 which increase the functional activity of the liver, a more 

 or less permanent active congestion results, (b) Various 

 poisons provoke a severe form of congestion of the liver. 

 These include many autogenic poisons carried to the liver 

 from the intestinal tract by the portal vein, or certain 

 ptomaines preformed in the food before it is ingested. Min- 

 eral poisons (arsenic, mercury, phosphorus) can produce it. 

 Some of the toxic products of infections, which develop in 

 the intestinal tract, will sometimes be carried to the liver in 

 sufficient quantities to excite an acute congestion, (c) Con- 

 gestion of the liver may also result from the specific products 

 of certain infections (virus of distemper, staphylococci and 

 streptococci) that may reach the liver via the general circula- 

 tion, (d) Dogs, when kept indoors, fed on highly nutritious 

 food, and not receiving the proper amount of exercise, will 

 often develop active congestion of the liver. 



Many of the causes mentioned are also the chief etiological 

 factors in producing inflammation of the liver (hepatitis) 

 of which congestion is the first stage. 



Pathology. — The liver is enlarged, feels firm or hard, 

 contains an increased amount of blood, and is of a dark red 

 or reddish-brown color. On cut surface, the blood drips or 

 flows off freely. 



