462 DISEASES OF THE HORSE, 
Erythema may arise from a variety of causes, and is often named 
in accordance with its most prominent cause. Thus the chilling, or 
partial freezing, of a part will give rise to a severe reaction and con- 
gestion. When snowy or icy streets have been salted this may extend 
to severe inflammation, with vesicles, pustules, or even sloughs of 
circumscribed portions of the skin of the pastern (chilblain, frost- 
bite). Heat and burning have a similar effect, and this often comes 
from exposure to the direct rays of the sun. The skin that does not 
perspire is the most subject, and hence the white face or white limb 
of a horse becoming dried by the intensity of the sun’s rays often 
suffers to the exclusion of the rest of the body (white face and foot 
disease). The febrile state of the general system is also a potent 
cause; hence the white-skinned horse is rendered the more liable if 
kept on a heating ration of buckwheat, or even of wheat or maize. 
Contact of the skin with oil of turpentine or other essential oils, with 
irritant liquids, vegetable or mineral, with rancid fats, with the acrid 
secretions of certain animals, like the irritating toad, with pus, sweat, 
tears, urine, or liquid feces, will produce congestion or even inflam- 
mation. Chafing is a common cause, and is especially liable to affect 
the fat horse between the thighs, by the side of the sheath or scrotum, 
on the inner side of the elbow, or where the harness chafes on the 
poll, shoulder, back, breastbone, and under the tail. The accumula- 
tion of sweat and dust between the folds of the skin and on the sur- 
face of the harness, and the specially acrid character of the sweat in 
certain horses, contribute to chafing or “intertrigo.” The heels often 
become congested owing to the irritation caused by the short, bristly 
hairs in clipped heels. Again, congestion may occur from friction by 
halter, harness, or other foreign body under the pastern, or inside the 
thigh or arm, or by reason of blows from another foot (cutting, inter- 
fering, overreach). Finally, erythema is especially liable to occur in 
spring, when the coat is being shed, and the hair follicles and general 
surface are exposed and irritable in connection with the dropping of 
the hairs. 
If due only to a local irritant, congestion will usually disappear 
when the cause has been removed, but when the feeding or system 
is at fault these conditions must be first corrected. While the coat is 
being shed the susceptibility will continue, and the aim should be to 
prevent the disease from developing and advancing so as to weaken 
the skin, render the susceptibility permanent, and lay the foundation 
of persistent or frequently recurring skin disease. Therefore at such 
times the diet should be nonstimulating, any excess of grain, and 
above all of buckwheat, Indian corn, or wheat, being avoided. A 
large grain ration should not be given at once on return from hard 
work, when the general system and stomach are unable to cope with 
