TEXAS FEVER. 479 



though mild, attack later on in the autumn, which pushes the full 

 recovery onward to the beginning of winter. 



In the mild type of the disease, which occurs in October and No- 

 vember, symptoms of disease are well-nigh absent. There is little 

 if any fever, and if it were not for loss of flesh and more or less dull- 

 ness the disease may pass unnoticed, as it undoubtedly does in a 

 majority of cases. If, however, the blood corpuscles are counted from 

 time to time a gradually diminishing number will be found, and 

 after several weeks only about one-fifth or one-sixth of the normal 

 number are present. It is indeed surprising how little impression 

 upon the animal this very impoverished condition of the blood ap- 

 pears to make. It is probable, however, that if two animals kept 

 under the same conditions, one healthy and the other at the end of 

 one of these mild attacks, are 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 examf)le. 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 are, how- 

 ever, a considerable number of changes caused by this disease which 

 may be detected by the naked eye when the body has been opened. 

 Put together they 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 have 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 any one 

 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 post-mortem ex- 

 aminations, 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. XLIV, 

 fig. 1), and may even well out as a disintegrated mass. The mark- 

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

 number of blood corpuscles which have collected in it, and to 

 which the enlargement is attributable. Xext to the spleen the liver 

 will arouse our attention. (See PI. XLV, fig. 2.) It is larger than 



