Parasites and Parasitic Diseases of Sheep. 27 
one side of the cyst is an opaque white object, which is the head and 
neck of a tapeworm (fig. 17).- When degenerated the cysts appear 
as cheesy or hard nodules, the hardness being due to lime salts. 
Life history.—The life history of this parasite is similar to that of 
the thin-necked bladderworm, the adult being a certain species of 
tapeworm of the dog (7wnia ovis). 
Distribution.—In the United States this parasite appears to be 
most common in the West, especially in Montana, Idaho, Washing- 
ton, Oregon, California, Colorado, and Nevada. It has been found 
abroad in England, France, Germany, Algeria, German Southwest 
Africa, New Zealand, and South America. 
Secaptoris and lesions.—When sheep have but a few of these cysts 
no symptoms are likely to be observed, although it has been sug- 
gested that sheep measles may be responsible for the many stiff 
lambs found during spring and summer on the western sheep ranges. 
When many cysts are present sheep will become very sick, and if all 
the eggs from one segment are eaten the sheep are likely to die. On 
post-mortem examination the cysts are the principal thing observed, 
though in badly infested cases the meat may be watery and dlis- 
colored. 
Treatment and prevention._—These are the same as for the thin- 
necked bladderworm (pp. 25 and 26) and its adult tapeworm. 
THE GID PARASITE.” 
Location.—The gid parasite occurs in the brain or spinal cord. 
Degenerate cysts that failed to reach the central nervous system may 
be found in muscles and other tissues. 
Appearance.—This worm occurs as a large cyst or bladderworm, 
attaining the size of a hen’s egg or larger, and is composed of a thin 
membrane containing a rather large amount of fluid. On the blad- 
der membrane are a number of small white objects about the size 
of a grain of wheat, projecting, as a rule, into the bladder fluid 
(fig. 18). These are the tapeworm heads. A parasite of this sort 
is called a ccenurus. 
Life history—When such a bladderworm, or ccenurus, is eaten vy 
a dog or coyote the bladder membrane digests, releasing the attached 
tapeworm heads. These heads then pass into the small intestine, 
where they form the adult tapeworm by the addition of segments 
back of the head (fig. 19). Ordinarily the worm is fully grown 
and 2 or 3 feet long in the course of a month or two, though oc- 
casionally a longer period is required. The full-grown tapeworm 
produces minute eggs, which pass out in the feces of the dog on to 
the pasture or range. Under favorable conditions these eggs are 
taken in by sheep with contaminated food or water. The shell 
4 
18 Wulticeps multiceps, Synonym, Cenurus cerebralis. 
