GREASE, OR CANKER. 445 



erysipelas, in which there is active fever (wanting in grease), the 

 implication of the deeper layers of the skin and of the parts beneath 

 giving a boggy feeling to the parts, the absence of the fetid, greasy 

 discharge, and finally a tendency to form pus loosely in the tissues 

 without any limiting membrane, as in abscess. Another distinctive 

 feature of grease is its tendency to implicate the skin which secretes 

 the bulbs or heels of the horny frog and in the cleft of the frog, con- 

 stituting; the disease known as canker. 



Causes. — The predisposing causes of grease are essentially the same 

 as those of simple infiannnation of the heel, so that the reader may 

 consult the preceding article, and though a specific fungus and bac- 

 teria of different kinds are present, they tend mainly to aggravation 

 of the disease, and are not proved to be essential factors in causation. 



Symptoms. — The symptoms vary according to Avhether the disease 

 comes on suddenly or more tardily. In the first case there is a sudden 

 swelling of the skin in the heel, with heat, tenderness, itching, and 

 stiffness, which is lessened during exercise. In the slower forms there 

 is only seen a slight swelling after rest, and with little heat or inflam- 

 mation for a week or more. Even at this early stage a slight serous 

 oozing may be detected. As the swelling increases, extending up 

 toward the hock or knees, the hairs stand erect, and are bedewed by 

 moisture no longer clear and odorless, but grayish, milky, and fetid. 

 The fetor of the discharge draws attention to the part whenever one 

 enters the stable, and the swollen pastern and wet, matted hairs on 

 the heel draw attention to the precise seat of the malady. If actively 

 treated, the disease may not advance further, but if neglected the 

 tense, tender skin cracks open, leaving open sores from which vascular 

 bleeding growths grow up, constituting the '' grapes." The hair is 

 shed, and the heel may appear but as one mass of rounded, red, angry 

 excrescences Avhich bleed on handling and are covered with the now 

 repulsively fetid decomposing discharge. During this time there is 

 little or no fever, the animal feeds well, and but for its local trouble it 

 might continue at work. When the malady extends to the frog, there 

 is a fetid discharge from its cleft or from the depressions at its sides, 

 and this irraduallv extends to its whole surface and ui)on the adjacent 

 parts of the sole. The horn meanwhile becomes soft, whitish, and 

 fleshy in aspect, its constituent tubes being greatly enlarged and 

 losing their natural cohesion: it grows rapidly above the level of the 

 surrounding horn, and when pared is found to be penetrated to an 

 unusual depth by the secreting papilla\ and that at intervals these 

 have bulged out into a vascular fungous mass comparable to the 

 " grapes." 



Treatment. — In treatment hygienic measures occupy a fi-ont rank, 

 but are in themselves insufficient to establish a cure. All local and 

 general conditions which favor the prodiu'tion and persistence of the 



