360 TEXAS FEVER 



the form of a mild type in the fall. The essential difference 

 between the two types is found in the different stages of the 

 parasite circulating in the blood. Unless the temperature is 

 taken and the blood carefully examined, mild types of Texas 

 fever would be either overlooked or mistaken for any one of a 

 variety of disorders common among cattle. 



§ 270. Morbid anatomy. Cattle which die of Texas 

 fever undergo post-mortem changes very rapidly. For this 

 reason the description of lesions made some hours after death 

 may be misleading. 



Externally the animal presents nothing abnormal or char- 

 acteristic of the disease. Rarely dried bits of blood may be 

 found and also some small slightly elevated areas of a bluish 

 color. The skin between the thighs, upon and about the 

 udder and possibly elsewhere may have cattle ticks attached. 

 It is important under ordinary circumstances to look for this 

 parasite. The subcutaneous tissue may be more or less yellow 

 in color. Edema of the subcutis over the ventral portion of 

 the body has been observed. The muscles are usually normal 

 in appearance although frequently they are pale. 



Very slight if any lesions have been recorded as occurring 

 in the central nervous system and lungs. Blood extravasa- 

 tions usually occur beneath the skin and endocardium, espe- 

 cially of the left ventricle. On the external surface the 

 petechiae occur for the greater part along the intraventricular 

 ■groove near the base. The capillaries of the heart muscle are 

 packed with corpuscles. Parenchymatous and fatty degene- 

 ration of the muscular fibers sometimes exists. The right ven- 

 tricle is distended with blood either fluid or clotted and the 

 left one firmly contracted. 



In the abdominal cavity there are frequent edematous 

 areas about the kidneys and in the portal regions between the 

 duodenum and liver. The omentum is often sprinkled with 

 peculiar hyperemic patches consisting of delicate shreds of 

 vascular tissue. This condition, however, is not characteristic 

 of Texas fever. 



