310 DR. LEGEAR'S STOCK BOOK. 



the disease. And throughout this period not a tiek was found 

 on tin- Missouri cattle; nor could any be found on the Texas cat- 

 tle, save a few brought with them, which soon disappeared. It 

 would appear from this experiment that great benefits would 

 accrue to the cattle and farming industry of the whole country 

 from the dipping process; the danger of infecting northern ter- 

 ritory in the transfer of these animals would be overcome; a mar- 

 ket previously closed would be opened to summer feeders in the 

 North, in seasons of abundance of corn and grass and a scarcity 

 of cattle. 



Nature and Cause. Texas fever is caused by a micro-parasite 

 (little animal living on another) which lives within the red blood- 

 corpuscles and destroys them. It is therefore a disease of the 

 blood. The little organism is carried and introduced into the 

 blood of animals by the cattle tick (boophilus bovis) which may 

 be found on nearly all Texas cattle. It is not, therefore, a micro- 

 scopic plant, but it belongs to the lowest form of animal life. 

 This very little animal multiplies very rapidly in the body of the 

 infected animal, and in severe cases causes great destruction of 

 the red blood corpuscles in a short time. 



All the disease processes which go on in Texas fever, as seen by 

 examining the organs after death, all result from the destruction 

 of red blood-corpuscles. When this destruction is rapid, we have 

 the acute, usually fatal, type of Texas fever, usually witnessed 

 during the latter weeks of August and the early weeks of Septem- 

 ber. Cases of the mild type occurring early in the season usually 

 become acute later on and terminate fatally. 



Symptoms. The disease first shows itself in dullness, loss of 

 appetite, and a tendency to leave the herd and stand or lie down 

 alone. The temperature of the body, taken per rectum by a 

 fever thermometer (Fig. 19), shows an elevation, in acute eases, 

 to 106-107 degrees Fahrenheit. When the temperature does not 



