DISEASES OF HORSES AND CATTLE. 153 



the heart of the tumor. It is best applied with a 

 smooth piece of stick. 



Melanosis. — Melanotic tumors seem to be nat- 

 ural to gray horses, as they are seldom found on 

 other horses. Their structure consists of connec- 

 tive tissue, intermixed with black pigment cells. 

 They are of a cancerous nature and have been 

 called "black cancer." This form of cancer has 

 been found in nearly all kinds of domestic animals, 

 but most frequently in the gray horse. It is thought 

 that this pigment, which should have colored the 

 hair, is, under certain conditions of the horse, con- 

 centrated in one or more places, causing the forma- 

 tion of those black tumors. Their growth is some- 

 times rapid, at others very slow. Their usual place 

 of forming is on the black skin around the root 

 of the tail, or the udder, although I have seen some 

 cases in the iron gray horses where they have 

 made their appearance over the sides and on the 

 nose. I have removed and seen a great many 

 melanotic tumors, and they have always returned 

 sooner or later. They are of a malignant charac- 

 ter and are therefore incurable. 



Lymphoma. — This is a term given to a disease 

 which affects the glandular structures, and in cat- 

 tle usually the glands of the neck. Like the melan- 

 otic tumors they are sometimes of very slow devel- 

 opment and at others fast. When they affect the 

 glands of the throat and grow rapidly they usually 

 cause suffocation, and the result of such tumors 

 is fatal to the life of the animal. These tumors are 

 considered by some to be of the same nature as 



