488 BUREAU OF ANIMAL INDUSTRY. 



inflammation 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 lamina; 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 maj^ 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 inflam- 

 mation 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 b}^ irritants as al)ove, 

 and by sudden cooling of the surface of the animal, which drives the 

 blood to that organ which at the moment is most activel}'^ supplied with 

 blood. This is called repercussion. A horse which has been worked 

 at speed and is breathing rapidl}' is liable to have pneumonia if sud- 

 denly chilled, while an animal which has just been fed is more apt to 

 have a congestive colic if exposed to the same influence, 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 of color, due to an increased supply of blood; swelling, from the 

 same cause, with the addition of an effusion into the surrounding tis- 

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

 pressure on the nerves; and altered function. This latter ma}^ 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 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. 



The alterations in an inflamed tissue are first those of congestion, 

 distention of the blood vessels, and exudation of the fluid of the blood 

 into the surroiuiding fibers, with, however, a more complete stagnation 

 of the blood; fibrin, or lymph, a plastic substance, is thrown out as well, 

 and the cells, which we have seen to be living organisms in themselves, no 

 longer carried in the current of the blood, migrate from the vessels 

 and, finding proper nutriment, proliferate or multiply with greater or 

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

 rounding fibers are awakened into activity by the nutritious lymph 

 which surrounds them and they also multipl3^ 



Whether the cell in an inflamed part be the white ameboid cell of the 

 blood or the fixed connective tissue cell embedded in the fi])ers, it nnilti- 

 plies in the same way. The nucleus in the center is divided into two, 

 and then each again into two, ad infinitum. If the process is slow, 

 each new cell may assimilate nourishment and become, like its ancestor, 



