LOCAL INFLAMMATIONS 145 



horse-owners to this apparently unreasonable view, but it is now perfectly 

 well known that in establishments where washing has been discontinued 

 mud fever and cracked heels are of rare occurrence. 



In the human subject erythema exhibits itself in a great number of 

 forms, according to the situation of the disease and the character of the 

 cause which produces it. 



Erythema intertrigo is one of the forms which occur in the horse when 

 two surfaces of skin rub against each other, and the term may conveniently 

 be extended to include all those instances of redness following friction 

 from any part of the harness, saddle, or collar. It will be noticed, how- 

 ever, that the irritation induced by friction is not likely to be detected 

 in dark-coloured animals, and the cause therefore is frequently allowed 

 to continue until abrasions occur, and the so-called " shoulder galls" 

 appear. These conditions are common enough among working horses 

 wearing a badly-fitting collar, and are difhcult to deal with on account 

 of the impossibility of the healing process taking place so long as the 

 use of the collar is continued. The device which is resorted to, of 

 hollowing out a part of the collar which causes the abrasion, is only 

 partially successful. In order to dry up the abraded surface and harden 

 the skin, an astringent lotion is usually employed; a solution of chloride 

 of zinc, or bichloride of mercury, is generally effectual. A very convenient 

 lotion to be kept in the stables is made by mixing Sir William Burnett's 

 disinfecting fluid, in the proportion of one part to fifty of water, the Itottle, 

 of course, being marked with a poison label. 



Purpura is a form of erythema which occurs in the horse under the 

 name of purpura haemorrhagica. This disease consists in extravasation 

 of blood into the tissues of the true skin, either from dilatation and over- 

 distension of the vessels from deranged nerve-function, or from a morbid 

 condition of the blood itself. It can hardly be looked upon as a distinct 

 disease of the skin, but rather as an indication of some serious patho- 

 logical state of the system, which would generally be classed under 

 the heading of blood diseases. So far as the skin itself is concerned, 

 the disease is exhibited in the form of patchy elevations, associated 

 with blood - spots on the visible mucous membranes. The affection 

 appears to be peculiar to the horse, and is met with at the termination 

 of debilitating diseases, such as influenza and strangles. (See Purj^ura 

 Hfemorrhagica.) 



Urticaria— commonly described as nettle-rash — frecpently occurs in 

 the horse during the spring and summer months. The causes are a sudden 

 change of diet, especially from hard corn to fresh succulent herbage, such 

 as grass, clover, rye-grass, vetches, &c., drinking cold water when the 



