THE ANIMAL PARASITES OF CATTLE. 



515 



To prevent cattle from becoming infested with this parasite care 

 should be taken that human feces are not placed where they will 

 contaminate the feed or drinking water. 



GID. 



Bladder worms (Multiceps socialis, or Ccenurus cerebralis) which 

 are occasionally found in the brain of cattle, and cause gid, "turn- 

 sick," or "staggers," deserve mention, as they are rather common 

 among sheep in the Northwest. As already alluded to, these worms 

 are the intermediate stage of a tapeworm found in dogs, and their 

 life history and the means of preventing infection have been briefly 

 discussed above (see p. 513). 



Cattle harboring this parasite 

 show symptoms indicating an 

 affection of the brain, walking or 

 turning in circles, dizziness, un- 

 even gait, impaired vision, etc. 



Treatment consists in trephin- 

 ing the skull and removing the 

 parasite, an operation which re- 

 quires a skillful operator and is 

 frequently unsuccessful. Unless 

 ihe parasite is removed affected 

 cattle almost invariably die. 



THREAD WORMS IN THE ABDOM- 

 INAL CAVITY. 



Thread worms (FUaria labiato- „„„„». , , , ., . 



v Fig. 26. — Section of a pork tongue heavily m- 



papiUosa) 2 to 4 inches long are tested with pork measles. Beet tongues in- 

 frequently found in the abdominal fested with bee£ measles present a 8imilar 



- 1 J appearance. 



cavity. They seem to cause little 



or no trouble. The embryos produced by these worms enter the blood 

 vessels. Stable flies (see p. 496) while sucking blood take up these 

 embryos, which undergo a certain amount of development in the body 

 of the flies. These flies, again biting cattle, introduce the partially 

 developed worms with which they are infested into the circulation, 

 whence the worms migrate to the abdominal cavity and there develop 

 to maturity. The roundworms found occasionally in the anterior 

 chamber of the eye (see p. 516) are perhaps immature forms of this 

 species which have reached this location during their migration. 



LUNG WORMS. 



Lung worms (Dictyocaulus viviparus, fig. 27) in cattle are thread- 

 like worms 2 to 4 inches long, found in the bronchial tubes, and pro- 

 ducing a condition known as verminous bronchitis. (See PI. LII, 

 which represents a portion of lung with the bronchial tubes filled 

 with lung worms, drawn about twice natural size. ) The life history 



