506 



DISEASES OF CATTLE. 



Fig. 15. -Twisted 

 stomach worm 

 (Hcemonchus con- 

 tortus. ) 



\ 



The Twisted Stomach Worm (Hjemonchus contortus)." 2 



The twisted stomach worm (Hcemonchus contortus, figs. 15, 16, 17) is 



sometimes found in enormous numbers in the fourth stomach of cattle. 

 Sheep, goats, and other ruminants may also be infested 

 with it. Among the symptoms caused by this para- 

 site may be mentioned anemia, loss of flesh, general 

 weakness, dullness, capricious appetite, excessive 

 thirst, and diarrhea. The anemic condition is seen 

 in the pale- 

 ness of the 

 skin and 



mucous membranes of the 



mouth and eye, and in the 



watery swellings which often 



develop under the lower jaw 



("poverty jaw"). If the 



fourth stomach of a dead ani- 

 mal be cut open and the con- 

 tents carefully examined, the 



parasites, which are from 



one-half inch to 1^ inches in 



length and about as thick as 



an ordinary pin, may be seen, 



if present in any considerable 



number, actively wriggling 



about like little snakes. 

 Cattle become infected 



with these parasites by graz- 

 ing on pastures on which in- 

 fested cattle, sheep, or goats 



have grazed and scattered 



their droppings. The worms 



in the stomach produce a 



multitude of eggs (fig. 16c) of 



microscopic size, which pass 



out of the body in the feces. 



In warm weather these eggs 



hatch in a few hours. If the 



temperature is below 40° F. 



they remain dormant, and if 



below freezing they soon die. 



The eggs are also killed by 



dryness, moisture on the 



other hand favoring their 



Pig. 16.- 



-Twisted stomach worms (Haantmehnt 

 contortus). 



a A more extended discussion of this parasite appears in Circulars 93 and 102 of 

 the Bureau of Animal Industry. 



