HYPEREMIA OF THE LIVER. 



281 



the urine is of a dark lemon-yellow color ; the skin of the inferior 

 abdominal wall also becomes of à yellow tint. At an advanced 

 period we may observe hemorrhages upon the principal mucous 

 membranes. 



HYPEREMIA OP THE LIVER. 



Etiology. Congestion of the liver is active and passive. Its 

 causes are very numerous. The active hyperemia is produced nor- 

 mally at the time of the digestion, and abnormally in the various 

 diseases of this function, following the ingestion of an excessive 

 quantity of food, especially in subjects not having enough exercise 

 (fat dogs); after the administration of tainted, irritating food, or 

 food covered with mould at the onset of hepatitis. It may also 

 be determined by violent exertion, or by the great heat of summer; 

 it is frequent in warm, damp, and swampy countries. The low and 

 poorly-ventilated stables have been accused, but without sufficient 

 proof Passive congestion is often produced by an insufficiency of 

 the cardiac mitral valve, by chronic affections of the lungs (pul- 

 monary emphysema, chronic intestinal alterations, compressions of 

 the lungs in hydrothorax, etc.). In other cases it is observed as a 

 secondary phenomenon of the infectious diseases ; also of inflamma- 

 tory diseases of the intestinal canal, of cachectic conditions, and of 

 the parasitic diseases of the liver. 



Pathological anatomy. The congested liver is tumefied ; its 

 coloration is darkish ; and it has a relatively firm resistance ; the 

 centre of the lobules is dark, whilst the periphery is of a light tint. 

 When hyperemia persists for some time the particular alteration 

 designated by the expression ^' nutmeg liver is created ; dark 

 parts alternate with grayish portions and give the liver a bronzed 

 aspect, which is similar to that of nutmeg ; histologically, this lesion 

 is produced by the dilatation of the central hepatic veins, determin- 

 ing, consecutively, compression, fatty degeneration, pigmentation, 

 and finally the atrophy of the hepatic cells (passive congestion). In 

 the course of chronic hyperemias of the liver, hemorrhages some- 

 times take place in the hepatic parenchyma and give it a particular 

 pigmentation (Anacker). According to this author, this form of 

 pigmentation of the liver is found quite commonly in animals sent 

 to the slaughter-house ; in others it is a peculiarity of the race, or 

 a kind of melanemia. 



Symptoms. These are very vague, and in consequence the 



