THE ANIMAL PARASITES OF CATTLE. 



511 



may cause inflammation and occasionally rupture of the intestine. 

 Infection occurs through the swallowing of the eggs of the parasite 

 in food or water which has been contaminated with the feces of 

 infested cattle. 



A number of species of small roundworms, varying in size from an 

 eighth of an inch to an inch or more in length, occur in the intestines. 

 Of these may be mentioned the hook worm {Monodontus phlebotomus) 

 and the nodular worms 

 (CEsophagostomum colum- 

 bianum and O. radiatum). 

 The former is about an inch 

 long and is found in the 

 smail intestine. The latter 

 are somewhat smaller and 

 are found in the cecum and 

 large intestine. Hook 

 worms, when numerous, 

 may cause anemia and 

 other symptoms similar to 

 those caused by stomach 

 worms (see p. 506). The 

 injury to the mucous lining 

 of the intestine from the 

 bites of hook worms may 

 cause severe inflammation, 

 and affords an avenue of 

 infection with the germs of 

 various diseases. The 

 adult nodular worms ap- 

 parently do not attack the 

 wall of the intestine, but 

 derive their nourishment 

 from the intestinal con- 

 tents. Several species of 

 small, very slender round- 

 worms (TricJwstrongylus), 

 less than a quarter of an 

 inch in length, sometimes 

 occur in the small intestine 

 and fourth stomach, and a severe gastro-enteritis, or inflammation of 

 the stomach and intestines, has been attributed to them. 



Nodular disease of the intestine, due to young hook worms and 

 nodular worms which burrow in the intestinal wall, as a rule seems 

 to have little effect on the health of infested animals, but often ren- 

 ders the intestine unfit for use as sausage casings. As nodular dis- 

 ease is widely prevalent among cattle, the loss from this source is 



Fig. 20.— A tapeworm (Moniezia pianissimo.) which in- 

 fests cattle. 



