DISEASES OF THE HOESE. 13 



expression of an animal in disease as well as in health depends to a 

 large extent on the temperament. 



THE SKIX AND THE VISIBLE MUCOUS MEMBRANES. 



The condition of the skin is a fair index to the condition of the 

 animal. The effect of disease and emaciation upon the pliability of the 

 skin ha\^e been referred to above. There is no part of the body that 

 loses its elasticity and tone as a result of disease sooner than the skin. 

 The practical herdsman or flockmaster can gain a great deal of infor- 

 mation as to the condition of an animal merely by grasping the coat 

 and looking at and feeling the skin. Similarh^, the condition of the 

 animal is shown to a certain extent by the appearance of the mucous 

 membranes. For example, when the horse is anemic as a result of 

 disease or of inappropriate food the mucous membranes become pale. 

 This change in the nuicous membranes can be seen most readily in the 

 lining of the ej'elids and in the lining of the nostril. For convenience 

 of examination the e3^elids can readily be everted. Paleness means 

 weak circulation or poor blood. Increased redness occurs physioiogic- 

 alh' in painful conditions, excitement, and following severe exertion. 

 Under such conditions the increase of circulation is transitoiy. In 

 fevers there is an increased redness in the* mucous membrane, and this 

 continues so long as the fever lasts. In some diseases red spots or 

 streaks form in the mucous membrane. This usually indicates an 

 infectious disease of considerable severity, and occurs in blood poison- 

 ing, purpura hemorrhagica, hemorrhagic septicemia, and in urticaria. 

 When the liver is deranged and does not operate, or when the red- 

 l)lood corpuscles are broken down, as in serious cases of influenza, 

 there is a yellowish discoloration of the mucous membrane. The 

 mucous membranes become bluish or blue when the blood is imper- 

 fectly oxidized and contains an excess of carbon dioxide. This condi- 

 tion exists in any serious disease of the respiratoiy tract, as pneumonia, 

 and in heart failure. 



The temperature of the skin A'aries with the temperature of the 

 liod}'. If there is fever the temperature of the skin is likely to be 

 increased. Sometimes, however, as a result of poor circulation and 

 irregular distribution of the blood, the body may be warmer than 

 normal, while the extremities (the legs and ears) may be cold. Where 

 the general surface of the bod}^ becomes cold it is evident that the 

 small blood vessels in the skin have contracted and are keeping the 

 blood away, as during a chill, or that the heart is weak and is unable 

 to pump the blood to the surface, and that the animal is on the verge 

 of collapse. 



The skin is moist, to a certain degree, at all times in a healthy horse. 

 This moisture is not in the form of a perceptible sweat, but it is enough 

 to keep the skin pliable and to cause the hair to hav^e a soft, healthy 



