530 DISEASES OF CATTLE. 



naked eye. These small organisms apparently are in no way injuri- 

 ous. A species of fluke {Paramphhtomum rervi or a closely related 

 species) is occasionally found in North American cattle, especially 

 grass-fed cattle, attached to the inner surface of the first stomach 

 (fig. 17). This worm is about one-half inch long, and somewhat 

 conical in shape, hence the name, conical fluke, by which it is some- 

 times known. Although this parasite has been accused of producing 



serious effects, it is generally considered 



harmless. 



Several species of roundworms may occur 



in the fourth stomach. Two of these are of 



special imix)rtance. 



The Twisted Stomach Worm (H^emonchus 

 contobtus)/ 



The twisted stomach worm {Hcemonehus 

 Fig. iT.-Portionofthewaii confortm, figs. 18, 19, 20) is sometimes 

 of tho first stomach with fouud in enormous numbers in the fourth 

 conical nuk,-. attached. gtomach of cattle. Sheep, goats, and other 



ruminant.^ may also be infested with it. Among the symi)toms 

 caused by this parasite may l)e mentioned anemia, loss of flesh, 

 general weakness, dullness, capricious appetite, excessive thirst, and 

 diarrhea. The anemic condition is seen in the paleness of the skin 

 and mucous membranes of the mouth and eye, and in the watery 

 swellings which often develop under the lower (" poverty jaw "). 

 If the fourth stomach of a dead animal be cut open and the 

 contents carefidly examined, the parasites, ^_^.-~-..>.^ 



which are from | inch to 1^ inches in length 

 and about as thick as an ordinary pin, may 

 be seen, if present in any considerable 



, ^ . \ ... u 4. ri r^^i Fi«- 18-— Twisted stom- 



number, activelv wriggling about like little ach worm (Hwmon- 



SnakeS. ' ''""' <">ntortus). 



Cattle become infected with these parasites by grazing on pastures 

 on Avhich infested cattle, sheep, or goats have grazed and scattered 

 their droppings. The worms in the stomach produce a multitude of 

 egp^s (fig. Idc) 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 development. The embryos which 

 hatch from the eggs are microscopic in size and like the eggs are 



lA more extended discussion of this parasite appears in Circulars 93 and 102 of the 

 Bureau of Animal Industry. 



