676 DISEASES OF THE SKIX. 



This form of eczema is frequently seen in the horse, under 

 the well-known appellation of " grease," which may be defineil 

 to be an inflammation of the skin at the back of the heels and 

 fetlocks, where vesicles and pustules form, yielding a foetid 

 discharge. The disease is sometimes associated with febrile 

 disturbance. In some instances, swelling of the limb or limbs 

 affected may precede the eruption ; whilst in others, the eruption 

 precedes the swelling. The hind limbs are more frequently 

 affected than the fore ones. The discharge is sometimes very 

 profuse, and it is said that it is capable of inducing an eruption 

 in cows and human beings similar to that of variola ; on this 

 account it has been termed equine lymph. 



I am of opinion that the evidence as to the specific character 

 of this equine lymph is not sufficient to warrant a conclusion, 

 and that the subject is deserving of further investigation. 



The discharge from the pustules and vesicles of grease irritates 

 the surface over which it flows; and the skin of the heels 

 — which in health is peculiarly soft and pliable — becomes 

 rigid ; the natural sebaceous secretion of its follicles is arrested, 

 and, as a consequence, the movements of the limb cause the 

 skin to crack, and to become a mass of soreness, ulceration, and 

 fungus, accompanied by heat, pain, and lameness. When tlie 

 disease is of this type, it is very apt to assume a chronic char- 

 acter. The febrile symptoms, along with the heat, pain, and 

 lameness, diminish; but the swelling still continues, and the 

 skin is constantly moist and greasy from the discharge, which 

 is thick, foetid, and mats the hairs together. Masses of fungoid 

 granulations now appear, springing from the unhealthy sores, 

 consisting of hypertrophied papillae, covered over by abnormal 

 horny scales of epithelium, loosely attached to their surfaces, 

 easily rubbed off, and exposing a highly-vascular sensitive 

 surface beneath, which bleeds at the slightest touch. These 

 excrescences are commonly called " grapes," and they belong to 

 a class of skin diseases described by dermatologists as " acne," 

 or chronic inflammation of the sebiparous glands, characterised 

 by the eruption of hard, conical, and isolated elevations, which 

 sometimes suppurate on their summits, or pour forth an in- 

 ordinate quantity of secretion ; whilst in other cases their action 

 is torpid, the sebaceous matter is concreted into a solid form, 

 and distends the excretory duct and hair follicle even to the 



