INFECTIOUS DISEASES OF CATTLE. 485 



second, though mild, attack hiter on iii the autumn, Avhich 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 weP 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 might pass unnoticed, as it undoubtedly does in a 

 majority, of cases. If, however, the blood corpuscles be 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 nor- 

 mal number are present. It is indeed surprising how little impres- 

 sion upon the animal this ver}'- impoverished condition of the blood 

 appears 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, 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. how- 

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

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

 Tliese, put together, make a mistake quite impossible. The presence 

 of small ticks (m the skin of the escut<'heon, 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 i-equire 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. XLVI, 

 fig. 1), and may CAen well out as a disintegi'ated mass. The mark- 

 ings 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 enlargement is due. Next to the spleen the liver will 

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

 in the healthy state, has lost its natural brownish color (fig. 1), and 



