540 



DISEASES OF CATTLE. 



Cattle harboring tbis parasite show symptoms indicating an af- 

 fection of the brain, walking or turning in circles, dizziness, uneven 

 gait, impaired vision, etc. 



Treatment consists in trephining the skull and removing the para- 

 site, an operation which requires a skillful operator and is frequently 

 unsuccessful. Unless the parasite is removed affected cattle almost 

 invariably die. 



THREAD WORMS IN THE ABDOMINAL CAVITY. 



Thread worms {Filana lahiato-'papillosa) 2 to 4 inches long are fre- 

 quently found in the abdominal cavity. They seem to cause little or 

 no trouble. The embryos produced by these worms enter the bl jd 

 vessels. Stable flies (see p. 519) while sucking blood take up t) >e 

 embryos, which undergo a certain amount of development in the 1 y 



of the flies. These flies, a^ 

 biting cattle, introduce the i 

 tially developed worms \\ . 

 which they are infested into t 

 circulation, whence the wor s 

 migrate to the abdominal cavity 

 and there develop to maturity. 

 The roundworms founa t • 

 casionally in the anterior cham- 

 ber of the eye (see p. 541) are 

 perhaps immature forms of this 

 species which have reached this 

 location during their migration. 



LUNG WORMS. 



^'?\^-^'!^'' f ''' ^7" '""Tl ^^^""'^ Lung worms (Dirty ocaulus 



infested with pork measles. Beef tongues ^ & ^ "^ 



infested with beef measles present a vivipams^ fig. 30) in cattle are 



Similar appearance. threadlike WOrmS 2 tO 4 iuchcS 



long, found in the bronchial tubes, and producing 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 of the parasite is not known, 

 but infection is apparently derived through the medium of pastures 

 where infested cattle have grazed. In the later stages of the dis- 

 ease the cattle cough, especially at night. Young cattle are more 

 seriously affected than old animals. 



Treatment for lung irorms. — Various treatments have been advo- 

 cated for lung worms, including fumigating with different substances 

 and injections of remedies into the trachea by means of a large hypo- 

 dermic syringe, but none has been very successful from a practical 



