144 HEALTH AND DISEASE 



Erythema is the term applied to any redness of the skin, whether or 

 not it is associated with an eruption. In its simple form erythema consists 

 of patches of redness, which may be caused by friction, stimulating appli- 

 cations, and, in short, by any irritating substance which will bring about 

 congestion or undue fulness of the vessels. 



Erythema iutertrigo is the name given to the redness produced by 

 friction between two surfaces of the skin, as sometimes occurs between 

 the arm and the brisket that part which is called the axilla; it occurs 

 also in the groin, especially of fat animals. 



A very characteristic form of erythema in the horse is familiarly known 

 as " mud fever ", on account of the disease occurring in wet seasons, when 

 the ground is soft and sloppy. It is a common ailment among hunters, 

 especially when cold winds prevail, and the legs and body become splashed 

 with mud and made repeatedly wet and dry in the course of a hard day's 

 hunting. It is somewhat curious that in particular districts the irritation 

 caused by the mud is most marked, and certain parts of the country 

 are credited with having soil contaminated with some irritating matter, 

 which, however, cannot be discovered by most careful examination. 



The disease is manifested by irritation, soreness, and tumefaction of the 

 skin, generally accompanied by a certain degree of fever, swelling of the 

 legs sometimes incapacitating the animal for several days. It now and 

 again occurs that the hair falls off in patches, but the blemish thus caused 

 is not as a rule permanent. 



A similar disease of the skin is also recognized among hacks and 

 working horses under certain circumstances, irrespective of locality. 

 Animals used for any purposes during muddy weather, and particularly 

 when the nature of their work renders it necessary that they should be 

 constantly in use, often suffer severely. The disease is commonly most 

 marked in the winter-time when snow is on the ground, and more par- 

 ticularly when a sudden thaw takes place and cold easterly and north- 

 easterly winds prevail. In this connection it has been noticed that in 

 certain establishments, where the pressure of work or the shortness of hands 

 occasioned neglect of grooming, the animals which on coming in from their 

 work were turned into their stalls without having the mud washed from 

 the legs and body escaped the mud fever altogether, while those which 

 were carefully groomed and had the mud thoroughly washed from their 

 skins were invariably attacked. As a matter of course, this fact came 

 under the observation of veterinary surgeons, who were, from the nature 

 of their avocation, in the best possible position to test the truth of 

 the presumption that washing the mud from the legs and body of the 

 horses was a cause of mud fever. It took a long time to reconcile 



