INFECTIOUS DISEASES OF CATTLE 321 



plasma higeminum (Fig. 122). It is present in the blood of 

 cattle that are affected with this disease. The natural method 

 of entrance into the body is throngh the bite of the cattle tick. 

 The disease may be transmitted by inoculating blood containing 

 the parasite into a susceptible animal. - 



There are two forms of the disease, the acute and chronic. 



The symptoms of the acute form of the disease are a high 

 fever, depression, loss of appetite, diarrhrra, dark or bloody 

 urine, staggering gait and delirium. Death may occur within 

 a few days from the time the first symptoms are manifested. 



The symptoms of the chronic form of the disease resemble 

 the acute form, but are more mild. 

 The animal is unthrifty and loses 

 flesh rapidly. The bloodless condition 

 of the body is manifested by the pale, 

 visible mucous membrane. Death 

 seldom occurs. 



The most characteristic diseased 

 changes found on post-mortem exami- 

 nation occur in the liver and spleen. 

 The liver is enlarged, and a yellow- Fig. 122.— Biood-ceiis with Pir^ 



" ' ^ plasma bigeminum in them. 



ish, mahogany-brown color. The gall- 

 bladder is filled with a very thick bile. The spleen may be 

 several times the normal size and dark colored. When it is cut 

 into, the pulpy tissue may resemble thick, dark blood. The 

 kidneys are pale and the bladder may contain dark or reddish- 

 colored urine. 



In the northern States and outside of the quarantined area, 

 the direct or indirect exposure of the affected cattle to southern 

 cattle, and the presence of the cattle tick, Margarophus anuu- 

 latus, are sufficient evidence to confirm the diagiiosis of this 

 disease. 



The prevention and control depend on destruction of the 

 cattle tick. In the early history of the disease, shipping and 

 21 



