472 DISEASES OF THE HORSE. 



INFLAMMATION OF THE HEELS WITH SEBACEOUS SECRETION 

 (GREASE, OR CANKER). 



Tliis is a specific affection of the heels of horses usually associated 

 with the growth of a parasitic fungus, an olfensive discharge from 

 the numerous sebaceous glands, and, in bad cases, the formation of 

 red, raw excrescences (grapes) from the surface. It is to be distin- 

 guished (1) from simple inflanunation in which the special fetid 

 discharge and the tendency to the formation of " grapes" are absent; 

 (2) from hoisepox, in which the abundant exudate forms a firm, 

 yellow incrustation around the roots of the hair, and is embedded 

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

 there is no vascular excrescence; (3) from foot scabies (mange), 

 in which the presence of an acarus is distinctive; (4) from lymphan- 

 gitis, 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 (want- 

 ing in grease), the implication of the deeper layers of the skin and 

 of the parts beneath giving a bogg^^ feeling to the parts, the absence 

 of the fetid, greasy discharge, and finally a tendency to form pus 

 looseh' 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, constituting the disease known as canker. 



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

 as those of simple inflanmaatiou' of the heel, so that the reader may 

 <onsult the preceding section. Though a specific fungus and bac- 

 teria of different kinds are present, they tend mainly to aggi'avation 

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



Synrbptoms. — The symptoms vary according to whether the disease 

 ccmes on suddenh' 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 seen only 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 paii; when- 

 ever one enters the stable, and the swollen pastern and wet, matted 

 hairs on the heel draw attention to the seat of the malady. If ac- 

 tively 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 



