Neoplasms in Horses Liver. 529 



The whole organ may be infiltrated so that in the end its outer 

 surface is completely hidden by melanotic deposit. The sur- 

 face deposits tend to project in more or less rounded, smooth 

 masses of varying size according to the age of the deposit and the 

 rapidity of its growth. Individual depoisits may vary in size from 

 a pea to a mass of 40 or 50 lbs. They are moderately firm, and 

 resLstant, and maintain a globular or ovoid outline. The color of 

 the melanotic depo.sits is a deep black with a violet or bluish tint. 

 If the pigmentary deposit is in its early stage it may be of a dark 

 gray. The deposits are firmer than the intervening liver tissue 

 and rarely soften or suppurate. 



Melanosis in the hor.se is not always the malignant disease that it 

 shows itself to be in man, and extensive deposits may take place 

 externally and considerable formations in the liver and other in- 

 ternal organs without serious impairment of the general health. 

 It is only in very advanced conditions of melanosis of the liver that 

 appreciable hepatic disorder is observed. If, however, there is 

 marked enlargement of the liver, in a white or gray horse, which 

 shows melanotic tumors on the surface, hepatic melanosis may 

 be inferred. 



Lymphadenoma . Adenoid Tumor. I/ienaux describes cases of 

 this kind in which the liver was mottled by white points which 

 presented the microscopical character of adenoid tissue, cells en- 

 closing a follicle and a rich investing network of capillaries. 



Angioma. These are rare in the horse's liver, but have been 

 described by Blanc and Trasbot as multiple, spongy tumors on the 

 anterior of the middle lobe, and to a less extent in the right and 

 left, of a blackish brown color, soft and fluctuating. The largest 

 mass was the size of an apple, and on section they were found to 

 be composed of vascular or erectile tissue. The tendency is to 

 rupture and extensive extravaisation of blood (30 to 40 lbs.) into 

 the peritoneum. 



Carcinoma. Epithelioma. These forms of malignant disease ' 

 are not uncommon in the liver as secondary depo.sits, the primary 

 lesions being found in the spleen, stomach, intestine, or pancreas, 

 or more distant still, in the lungs. The grafting or colonization 

 of the cancer in the liver depends on the transmission of its ele- 

 ments through the vena portse in the one case, and through the 

 pulmonary veins, the left heart and hepatic artery in the other. 



34 



