86 HORSE, SWINE AND POULTRY DISEASES 



skin of the extremities, greasy heels, thrush, etc. Young horses 

 have inflammation of the membranes lining the air passages and 

 digestive tract, while older animals are more subject to troubles in 

 the closed serous sacs and in the bones. 



The work to which a horse is put (saddle or harness, speed or 

 draft) will influence the predisposition of^an animal to inflamma- 

 tory diseases. As in congestion, the functional activity of a part is 

 an important factor in localizing this form of disease. Given a 

 group of horses exposed to the same draft of cold air or other excit- 

 ing cause of inflammation, the one which has just been eating will 

 be attacked with an inflammation of the bowels; the one that has 

 just been working so as to increase its respiration will have an in- 

 flammation of the throat, bronchi, or lungs; the one that has just 

 been using its feet excessively will have a founder or inflammation 

 of the laminse of the feet. 



The direct cause of inflammation is usually an irritant of some 

 form. This may be a pathogenic organism a disease germ or it 

 may be mechanical or chemical, external or internal. Cuts, bruises, 

 injuries of any kind, parasites, acids, blisters, heat, cold, secretions, 

 such as an excess of tears over the cheek or urine on the legs, all 

 cause inflammation by direct injury to the part. Strains or wrenches 

 of joints, ligaments, and tendons cause trouble by laceration of the 

 tissue. 



Inflammations of the internal organs are caused by irritants 

 as above, and by sudden cooling of the surface of the animal, which 

 drives the blood to that organ which at the moment is most actively- 

 supplied with blood. This is called repercussion. A horse which 

 has been worked at speed and is breathing rapidly is liable to have 

 pneumonia if suddenly chilled, while an animal which has just been 

 fed is more apt to have a congestive colic if exposed to the same in- 

 fluence, the blood in this case being driven from the exterior to the 

 intestines, while in the former it was driven to the lungs. 



Symptoms. The symptoms of inflammation are, as in con- 

 gestion, change of color, due to an increased supply of blood; swell- 

 ing, from the same cause, with the addition of an effusion into the 

 surrounding tissues; heat, owing to the increased combustion in the 

 part; pain, due to pressure on the nerves, and altered function. 

 This latter may be augmented or diminished, or first one and then 

 the other. In addition to the local symptoms, inflammation always 

 produces more or less constitutional disturbance or fever. A splint 

 or small spavin -will cause so little fever that it is not appreciable, 

 while a Severe spavin, an inflamed joint, or a pneumonia may give 

 rise to a marked fever. 



Termination of Inflammation. Like congestion, inflammation 

 may terminate by resolution. In this case the exuded lymph un- 

 dergoes chemical change, and the products are absorbed and carried 

 off by the blood vessels and lymphatics, to be thrown out of the body 

 by the kidneys, liver, the glands of the skin, and the other excretory 

 organs. The cells, which have wandered into the neighboring tis- 

 sues from the blood vessels, gradually disappear or become trans- 



