GREASE. 509 



action will follow the distention, and the sebaceous glands 

 will be stimulated both to an increased and an unhealthy 

 deposit : and they being here very numerous and large, 

 and requiring to secrete in proportion, it follows that in- 

 stead of the natural unctuous secretion of the skin of the 

 heels, they will now pour forth a serous fluid through 

 ulcerated cracks, or a general purulent one under the real 

 term of grease. Cold is unfavourable to absorption ; it like- 

 wise weakens the general energy of the parts, and it often 

 suspends the circulation ; and, when this has happened, on 

 the return of warmth the impetus of the blood is always 

 preternaturally increased ; and the distended vessels, being 

 previously weakened, are rendered incapable of contracting 

 on their contents ; and it is perhaps principally to the pre- 

 sence of cold, and its effects on the constitution, that swelled 

 legs, cracks, and grease, are so much more common in 

 winter. Grease has even been called a winter disease, and 

 the chilblain of horses. Moisture is likewise favourable to 

 the complaint, for it first produces a determination to the 

 parts, and then, as a parent of cold, it weakens the already 

 distended vessels. It is stated by an officer of a dragoon 

 regiment, that, when stationed in America, another officer 

 being favourable to the custom of washing the heels of 

 horses, was permitted to exercise it on his own troop ; the 

 result was, that this individual troop in three months fur- 

 nished more than twenty horses with grease, the remainder 

 of the regiment not more than two or three. The acclivity 

 of the stalls in our stables has been considered as aiding the 

 other causes of grease, and with some apparent propriety ; 

 for it tends to throw considerable weight on the hinder ex- 

 tremities ; this, by the unnatural position of the heels, puts 

 the parts on the stretch, and hence weakens them. Grease 

 will often follow injuries ; as halter casting, or indeed any 

 accidental abrasion, may bring it on. The disease may 

 become serious when it occurs under other circumstances 

 favourable to its production, as in moist, cold, and par- 

 ticularly frosty or snowy weather ; or when, from previous 

 illness, a horse has been thrown out of condition ; and, 

 more than all, when such a case has been maltreated by the 

 idleness or ignorance of those around, who, finding a swelled 

 heel, immediately fly to urine balls, or purging balls, whereas 



