467 



will inflnence the predisposition of an animal to iijfiammatory diseases. 

 Like in congestion, the functional activity of a part is an important 

 factor in localizing tliis form of disease. Given a group of horses ex- 

 posed to the same draft of cold air or other exciting cause of inflamma- 

 tion, the one which has jast been eating will be attacked with an in- 

 flammation of the bowels; the one that has just been working so as to 

 increase its respiration will have an inflammation of the throat, bronchi, 

 or lungs ; the one that has just been using its feet excessively will have 

 a founder or inflammation of the laminoe of the feet. 



The direct cause of inflammation is usually an irritant of some form. 

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

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

 an excess of tears over the cheek or urine on the legs, all cause inflam- 

 mation by direct injury to the part. Strains or wrenches of joints, liga- 

 ments, and tendons cause trouble by laceration of the tissue. 



Inflammations of the internal organs arc 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 if suddenly chilled is liable to have 

 pneumonia, while an animal which has just been fed if exposed to the 

 same inflnence is more apt to have a congestive colic, 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 congestion, 

 change oi color, due to an increased supply of blood; swelling, from the 

 same cause, with the addition of an efl'asion into the surrounding tis- 

 sues; /terti, owing to the increased combustion in the part; pain, due to 

 pressure o\\ thQw^vxe^, ixud altered function. This latter may be aug- 

 mented or diminished, or first one and then the other. In addition to 

 the local symptoms, inflammation always produces more or less con- 

 stitutional disturbance ov 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. 



The alterations in an inflamed tissue ti.re first those of congestion, dis- 

 tension of the blood vessels, and exudation of the fluid of the blood into 

 the surrounding fibers, with, however, a more complete stagnation of 

 the blood; fibrine or lymph, a glue-like substance, is thrown out as 

 well, and the cells, which we have seen to be living organisms in them- 

 selves, no longer carried in the current of the blood, migrate from the 

 vessels and finding proper nutriment proliferate or multiply with greater 

 or less rapidity. The cells which lie dormant in the meshes of the sur- 

 rounding fibers are au^akened into activity by the nutritious lymph 

 which surrounds them and they also multiidy. 



Whether the cell in an inflamed part is the white amceboid cell of the 

 blood or the fixed connective tissue cell embedded in the fibers, it multi- 



