DISEASES OF HORSES 307, 



sent; (2) from horsepox, in which the abundant exudate forms a 

 firm yellow incrustation around the roots of the hair, and is embed- 

 ded, at intervals in the pits formed by the individual pocks, and in 

 which there is no vascular excrescence; (3) frojn foot scabies 

 (mange), in which the presence of an acarus is distinctive; (4) from 

 lymphangitis, in which the swelling appears suddenly extending 

 around the entire limb as high as the hock, and on the inner side of 

 the thigh along the line of the vein to the groin, and in which there 

 is active fever, and (5) from 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 im- 

 plicate the skin which secretes the bulbs or heels of the horny frog 

 and in the cleft of the frog, constituting the disease known as canker. 

 Causes. The predisposing causes of grease are essentially the 

 same as those of simple inflammation of the heel, so that the reader 

 may consult the preceding article, and though a specific fungus and 

 bacteria of different kinds are present, they tend mainly to aggrava- 

 tion of the disease, and are not proved to be essential factors in causa- 

 tion. 



Symptoms. The symptoms vary according to whether the dis- 

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

 sudden swelling of the skin in the heel, with heat, tenderness, itch- 

 ing, 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 inflammation 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 which bleed on handling and are 

 covered with the now repulsively fetid decomposing discharge. Dur- 

 ing 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 mal- 

 ady extends to the frog, there is a fetid discharge from its cleft or 

 from the depressions at its sides, and this gradually extends to its 

 whole surface and upon 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 



