466 DISEASES OF CATTLE. 



ditions, one healthy and the other at the end of one of these mild 

 attacks, be weighed, the difference would be plainly shown. 



Pathological changes observable after death. — In the preceding pages 

 some of these have already been referred to in describing the nature 

 of the disease. It is very important at times to determine whether a 

 certain disease is Texas fever or some other disease, like anthrax, for 

 example. This fact can, as a rule, be determined at once by a thorough 

 microscopic examination of the blood. The necessary apparatus and 

 the requisite qualifications for this task leave this method entirely in 

 the hands of experts. There is. however, a considerable number of 

 changes caused by this disease which may be detected by the naked 

 eye when the body has been opened. These, put together, make a 

 mistake quite impossible. The presence of small ticks on the skin of 

 the escutcheon, the thighs, and the udder is a very important sign in 

 herds north of the Texas- fever line, as it indicates that they have been 

 brought in some manner from the South and carried the disease with 

 them, as will be explained later. Another very important sign is the 

 thin, watery condition of the blood, either just before death or when 

 the fever has been present for four or five days. A little incision into 

 the skin will enable anyone to determine this point. Frequently the 

 skin is so poor in blood that it may require several incisions to draw 

 a drop or more. 



The changes in the internal organs, as found on postmortem exami- 

 nations, are briefly as follows : The spleen, or milt, is much larger than 

 in healthy animals. It may weigh three or four times as much. When 

 it is incised the contents or pulp is blackish (see PI. XLVI, fig. 1), and 

 may even well out as a disintegrated mass. The markings of the 

 healthy spleen (fig. 2) are all effaced by the enormous number of blood 

 corpuscles which have collected in the spleen and to which the enlarge- 

 ment is due. Next to the spleen the liver will arouse our attention. 

 (See PI. XL VII, fig. 2.) It is larger than in the healthy state, has lost 

 its natural brownish color (fig. 1), and now has on the surface a paler 

 yellowish hue. When it is incised this yellowish tinge or mahogany 

 color, as it has been called by some, is still more prominent. This is 

 due to the large amount of bile in the finest bile capillaries, and as 

 these are not uniformly filled with it the cut surface has a more or less 

 mottled appearance. This bile injection causes in many eases a fatty 

 degeneration of the liver cells, which makes the organ appear still 

 lighter in color. 



In all cases the gall bladder should be examined. This is distended 

 with bile, which holds in suspension a large quantity of yellow flakes, 

 so that when it is poured into a tall bottle to settle fully one-half or 

 more of the column of fluid will be occupied by a layer of flakes. If 

 mucus is present at the same time, the bile may become so viscid that 

 when it is poured from one glass to another it forms long bands. The 

 bile in health is a limpid fluid containing no solid particles. 



If the animal has not been observed during life to pass urine colored 



