MUD-FEVER—CRACKED HEELS—GREASE. 
647 
with the addition of adjectives like “erythematosa,” “verrucosa,” &c., 
appropriate to the particular form under consideration. 
Grease has been described by various writers, amongst others by 
Hertwig and Spinola, as an erysipelas. But this view is supported 
neither by the mode of origin nor by the course of the disease; and even 
though Malzef lately found, in cultures prepared from cases of equine 
grease, a micro-organism which appeared identical with Fehleisen’s 
streptococcus erysipelatis, yet latter-day views of the relationship of 
the streptococcus to erysipelas and to suppuration in no way bear out 
the above suggestion. 
Eczematous dermatitis, or mud-fever, is usually produced by external 
irritation either of a mechanical, chemical, or specific character. The 
disease often occurs soon after shoeing with high heels, because the 
changed position of the foot favours the formation of the folds in the skin 
just above the heels, in which sand and dirt lodge, and produce excoria¬ 
tion. One of the commonest causes of mud-fever and of cracked heels 
in town horses is to be found in the habit of washing horse’s heels with 
strong alkaline soaps (like soft soap) and hot water. The soap irritates, 
and the hot water produces vascular relaxation, liable to be followed by 
inflammation. Somewhat similar results are produced, in heavy horses, 
by washing the legs with a cold-water hose after returning from the 
day’s work. Omnibus and cab horses, whose legs are only roughly 
rubbed dry and are cleansed next morning with a brush, seldom suffer 
from any of these forms of dermatitis. An excellent method of drying 
and cleansing the legs simultaneously, is to rub them freely with clean 
pine sawdust. Animals working on stubble or freshly-laid roads or 
forest paths are apt to contract slight skin injuries, which sometimes 
form the point of origin of disease ; the wound discharges macerate the 
epithelium, irritate the skin, and produce inflammation. 
Griinwald describes an enzootic dermatitis which appeared during 
the hottest part of summer amongst horses stalled in open sheds, and 
in which the lower portions of the limbs were continually exposed to 
the sun’s rays. Horses sheltered from the sun were not affected, a 
fact which led Griinwald to compare the condition with erythema solare 
of man. 
Ivropfl noticed the same thing in horses at grass. Only the unpig- 
mented portions of skin in the hind limbs seemed to be diseased. 
Bermbach believed that mud-fever was conveyed from horse to horse 
by using the same washing-pails, Ac. More probably the same general 
external influences were at work. 
Amongst chemical irritants must be numbered chalk-dust. In the 
army its action is often troublesome, on account of horses becoming- 
affected immediately they are brought into chalky regions. Columella 
