Hydatids (Echinococcus granulosus) form tumors (fig. 22) of varying size (sometimes as large as 6 inches in diameter) in the liver, lungs, and other organs. Their contents are liquid, resembling water. The presence of these parasites can not be detected in the living animal and there is no medicinal treatment for them. Organs containing hydatids should be destroyed by burning in order to prevent their being eaten by dogs. This is especially important, as dogs infested with the tapeworm stage of this parasite are a menace to human beings on account of the danger of infecting them with hydatids, which develop in man if the eggs of the hydatid tapeworm are swallowed.
Thin-necked bladder worms (Tænia hydatigena, fig. 23) are most commonly found attached to the mesentery and omentum. There is no medicinal treatment.
Gid.—Bladder worms (Multiceps multiceps, or Cœnurus cerebralis), which are occasionally found in the brain of cattle and cause gid, "turnsick," 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. 527).
Cattle harboring this parasite show symptoms indicating an affection of the brain, walking or turning in circles, dizziness, uneven gait, impaired vision, etc.
Treatment consists in trephining the skull and removing the parasite, an operation which requires a skillful operator and is frequently unsuccessful. Unless the parasite is removed affected cattle almost invariably die.
TAPEWORM CYSTS IN THE MUSCLES, BEEF MEASLES.[19]
Fig. 23.—Thin-necked bladder worm (Tænia hydatigena) from abdominal cavity of a steer.
Small tapeworm cysts (Tænia saginatæ), about the size of a pea, found in the muscles of cattle are the larvæ of the common tapeworm of man. Cattle become infected from feed or water which has been contaminated by the feces of persons harboring the adult tapeworms, and human beings in turn become infected by eating raw or rare beef infested with the larval stage (measly beef).