292 THE MODERN HORSE DOCTOR. 



DISEASES OF THE SKIN AND SUB-CELLULAR TISSUES. 



GREASE, OR SCRATCHES. 



" The presence of grease is a pretty infallible test of negli- 

 gent grooming." — Percivall. 



Grease, or what is more generally known in the United States 

 as scratches, is a disease of frequent occurrence. It probably 

 originates, like many other cutaneous affections, in a foul habit 

 of body — a retention of morbific materials in the system, or, 

 more properly speaking, congestion of the superficial capillary 

 vessels. The disease is said to be most prevalent in the cold 

 months. We know that at this particular season the function 

 of the skin is more or less interrupted ; the insensible transpira- 

 tion, being neither so regular nor profuse as in the warm 

 months, must result in an accumulation of excrementitious mate- 

 rial ; hence the difficulty. 



The cavicy just above the heels of a horse, like that under the 

 axilla, or armpit, of man, is furnished with a large number of 

 exhalants — secreting and excreting glands ; and when the ani- 

 mal is in a state of health, and these vessels in a normal con- 

 dition, the moisture (if it may be so termed) keeps the parts 

 soft and pliant, lubricates the external surfaces, thus preserving 

 them against friction, irritation, and disease ; at the same time the 

 system is relieved from the burden of a large amount of morbid 

 matter. Sometimes the morbid materials are retained in the 

 immediate vicinity of the parts, in consequence of the accumula- 

 tion of filth on the surface, or from the chilling influence of a 

 draught of cold air on the legs after they have been washed. 



It is well known that variations of temperature always have a 

 :endency to disturb, and partially check, the cutaneous exhala- 

 tions ; yet they cannot be set down as direct causes of grease, 

 though they may be classed among the indirect. 



Mr. Percivall, in his lectures, thus refers to this disease : 

 " The etiology of grease throws considerable light upon its verita- 

 ble nature. Horses which are at pasture or in straw yards — 

 in situations, in fact, where heat and cold are not naturally, and 



