50 VETERINARY STUDIES 



Disorders of circulation and diseases of the organs of circula- 

 tion are numerous and of great importance, but too complicated 

 and difficult, as a rule, for the stockman to handle. The heart, 

 blood vessels, lymph vessels, and lymph glands are often involved 

 in disease. The heart may undergo a fatty degeneration, or it 

 may dilate, or the valves become diseased and fail to cloce their 

 openings. Arteries may become thin and weak, and dilate 

 greatly (aneurism), or become inflamed, degenerate and become 

 brittle, and then rupture (calcareous degeneration). Capil- 

 laries may be injured by toxic substances in the blood, then leak 

 or rupture (tissue hemorrhage). Veins become inflamed or the 

 venous wall may weaken and stretch, resulting in varicose veins. 



Lymph vessels and glands may become infected by bacteria, 

 then inflamed and swollen. The glands often suppurate, and 

 are destroyed after infection by the bacteria of tuberculosis, 

 glanders, etc. Ordinary "weed" or "elephant leg" (lymphan- 

 gitis) is a good example of disease of lymph vessels and glands. 

 This disease of horses is characterized by chill, then fever, and 

 sudden swelling of one hind leg on the inside and high up. This 

 swelling extends around the leg and down to the foot. After 

 the inflammation subsides, the limb is left larger than normal. 

 Both lymph vessels and lymph glands are involved and the 

 disease is apt to recur, each time leaving the leg larger than 

 before. 



