12 DISEASES OF THE HOESE. 



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 have a 

 soft, healthy feel. In some chronic diseased conditions and in fever, 

 the skin becomes dxy. In this case the hair has a harsh feel that is 

 quite different from the condition observed in health, and from the 

 fact of its being so dry the individual hairs do not adhere to one 

 another, they stand apart, and the animal has what is known as 

 "a staring coat." When, during a fever, sweating occurs, it is 

 usually an indication that the crisis is passed. Sometimes sweating is 

 an indication of pain. A horse with tetanus or azoturia sweats pro- 

 fusely. Horses sweat freely when there is a serious impediment to 

 respiration; they sweat under excitement, and, of course, from the 

 well-known physiological causes of heat and work. Local sweating, 

 or sweating of a restricted area of the body, denotes some kind of 

 nerve interference. 



Swellings of the skin usually come from wounds or other external 

 causes and have no special connection with the diagnosis of internal 

 diseases. There are, however, a number of conditions in which the 

 swelling of the skin is a symptom of a derangement of some other 

 part of the body. For example, there is the well-known " stocking," 

 or swelling of the legs about the fetlock joints, in influenza. There 

 is the soft swelling of the hind legs that occurs so often in draft 

 horses when standing still and that comes from previous inflamma- 

 tion (lymphangitis) or from insufficient heart power. Dropsy, or 

 edema of the skin, may occur beneath the chest or abdomen from 

 heart insufficiency or from chronic collection of fluid in the chest or 

 abdomen (hydrothorax, ascites, or anemia) . In anasarca or purpura 

 hemorrhagica large soft swellings appear on any part of the skin, 

 but usually on the legs, side of the body, and about the head. 



Gas collects under the skin in some instances. This comes from a 

 local inoculation with an organism which produces a fermentation 

 beneath the skin and causes the liberation of gas which inflates the 

 skin, or the gas may be air that enters through a wound penetrating 

 some air-containing organ, as the lungs. The condition here de- 

 scribed is known as emphysema. Emphysema may follow the frac- 

 ture of a rib when the end of a bone is forced inward and caused to 

 penetrate the lung, or it may occur when, as a result of an ulcerat- 

 ing process, an organ containing air is perforated. This accident is 

 more common in cattle than it is in horses. Emphysema is recog- 

 nized by the fact that the swelling that it causes is not hot or sensi- 

 tive on pressure. It emits a peculiar crackling sound when it is 

 •stroked or pressed upon. 



