Parasites and Parasitic Diseases of Sheep. 31 
Prevention.—The most important preventive measure is to destroy 
the heads or at least the brains of giddy sheep. This may be done 
by burning. Where wood is scarce the skull may be split with an 
ax or cleaver and the brain put on a forkful of hay or straw and 
burned. Where this is not feasible the brain may be removed from 
the skull, crushed, and covered with formaldehyde, turpentine, or a 
coal-tar or tobacco dip. The essential thing is to destroy the parasite 
and prevent dogs, coyotes, or other animals from eating it. 
Another measure of importance is to keep dogs, especially sheep 
dogs, free from tapeworms. To this end it is advisable that they 
be given tapeworm treatment four times a year. For the treatments 
that may be used see page 25. Measures against coyotes and other 
noxious wild animals are valuable in controlling gid as well as in 
keeping down the destruction of 
stock. Stray dogs should be elimi- 
nated on the same grounds. 
THE HYDATID.!* 
Location.—The preferred sites 
of the hydatid parasite in sheep are 
the liver and lungs, but it may occur 
in practically any organ or tissue. 
Appearance.—The parasite OC- Fic, 20.—Hog liver infested with hydatid f 
curs in sheep usually as a multiple saa eS 
bladderworm, varying from the size 
of a nut to the size of a child’s head, sometimes as a sphericai object 
and sometimes irregular in shape (fig. 20). It has a very thick, lami- 
nated bladder wall, and in the simplest form of the parasite this blad- 
der contains a clear fluid and minute objects resembling grains of 
sand lying unattached in the fluid. These grains are brood capsules, 
and each of them contains a number of very small tapeworm heads. 
Sometimes the bladderworm develops other bladderworms, attached 
or unattached, on the inside or outside. 
Life history—When the brood capsules from a hydatid are eaten 
by a dog, cat, or other suitable animal, each tapeworm head in the 
brood capsules develops into a tapeworm by the addition of segments 
back of the head. This tapeworm is a very small one, less than half 
a. centimeter (about one-fifth of an inch) long (fig. 21). As the 
hydatid may form thousands of such heads in its brood capsules, 
dogs may become infested with large numbers of these worms on 
eating hydatids. The eggs produced by the adult tapeworms in the 
dog pass out in the feces. When taken in by a sheep or other animal 
the egg hatches and releases an embryo which makes its way to some 
M4 Hehinoceceus granulosus, 
