14 DISEASES OF THE HORSE. 



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 indi- 

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

 of pain. A horse with tetanus or azoturia sweats profusely. Horses 

 sweat freely when there is a serious impediment to respiration ; they 

 sweat under excitement, and, of course, from the well-known physio- 

 logical 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 inflammation (lym- 

 phangitis) or from insufficient heart power. Dropsy, or edema of the 

 skin, may occur beneath the chest or abdomen from heart insuffi- 

 ciency or from chronic collection of fluid in the chest or abdomen 

 (hydrothorax, ascites, or anemia). In anasarca or purpura hemor- 

 rhagica 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. 



Wounds of the skin may be of importance in the diagnosis of 

 internal disease. Wounds over the bony prominence, as the point 

 of the hip, the point of the shoulder, and the greatest convexity of 

 the ribs, occurs when a horse is unable to stand for a long time and, 

 through continually lying upon his side, has shut off the circulation 

 to the portion of the skin that covers parts of the body that carry the 

 greatest weight, and in this way has caused them to mortify. Little, 

 round, soft, doughlike swellings occur on the skin and may be 

 scattered freely over the surface of the body when the horse is 



