CRACKED HEELS. ^56 



another, and deprives it of the oil which renders it soft and pliable. When 

 the epithelium dries after having beeil thus treated, it is hable to crack, 

 and thus to expose the true skin to irritation from dirt and grit, and from 

 impurities contained in the surrounding air or in the water wnich may gain 

 access to the part. The action of water in weakening the protective in- 

 fluence of the epidermis by dissolving out the oil previously contained in 

 it, is well shown by the fact that washing a horse's feet with warm water 

 is much more liable to give cracked heels than washing them with cold 

 water ; the former being the better means of the two for removing the oil, 

 and for softening the epithelium. Besides, if the water of a country con- 

 tains much mineral matter (such as salts of lime) which has a tendency to 

 increase the power water possesses to remove oil from the skin, we shall find 

 that horses in such a district are peculiarly liable to cracked heels. Water 

 containing such mineral matter would, with a weakened epidermis, probably 

 have a directly irritating effect on the true skin. The foregoing remarks 

 have been made with special reference to cracked heels. The role of infec- 

 tion in the production of grease is, as already indicated, an open question. 



The moisture and accumulated filth, as well as the ammonia, 

 found in unsanitary stables, play a large part in the production 

 of cracked heels and grease. Dew taken up by the feet from the 

 ground over which animals travel, and sweat running down and 

 drying on the pasterns, especially if there be a cold wind blowing 

 at the time, often cause cracked heels in horses, subject to these 

 influeiices, as in the cases of race horses, worked in the early 

 mornings. Other things being equal, horses which do their work 

 at fast paces, are more likely to get their heels chapped than 

 those whose work is slow. The skin that covers their pasterns 

 is subject to more violent and rapid flexion and extension than 

 that of slow going animals, and will proportionately suffer from 

 any derangement of the lubricating apparatus, which, here, is the 

 oil glands of the skin. The feeding of horses on unwholesome 

 oats appears to have a predisposing influence in the production of 

 cracked heels. 



As a rule, white pasterns are more liable to suffer from cracked 

 heels, especially among " pleasure horses," than dark-coloured 

 ones ; because dirt and stains show more prominently on them ; 

 consequently they get oftener washed, and have soap and other 

 alkaline preparations more frequently -applied to them. Grease 

 is much more common among Shires, than among light horses. 

 Experience shows that cold has a well-marked effect in producing 

 this disease. If blood, after having been expelled from the blood- 

 vessels and kept out of them for some time, be allowed to return 

 to the vessels, it will act as an irritant to their walls, and set up 

 inflammation. This appears to be the mode in which cold 

 produces inflammation of the skin of the pastern; for it renders 

 the part bloodless for the time being. 



Want of exercise, no doubt, has a strong predisposing influence 

 on this disease ; when the anirnal is kept in a state of enforced 



