PARASITIC DISEASES. 



167 



ternal parasites attack sheep. Only in isolated 

 localities are these found, and then usually in 

 low sections of the country, or in places long de- 

 voted to sheep husbandry. 



1. Gid. 



Sturdy; turn-sick. 



This ailment is due to the larva or hydatid 

 phase of the tapeworm, the Tae- 

 nia coenurus. 



The eggs of this tapeworm are 

 distributed around the pens or 

 corrals by carnivorous animals, 

 chiefly dogs. Other animals, 

 such as the coyote, wolf or fox, 

 may also be the host of this tape- 

 worm. 



After the eggs are ingested 

 by the sheep, it is supposed that 

 they hatch and the embryos 

 gain entrance to the circulatory 

 system by piercing the walls of 

 the stomach, although our knowledge of their 

 life history is incomplete. Those that reach the 

 brain or spinal cord develop into large cysts, 

 and cause this fatal malady among sheep. 



Symptoms: The manifestations of gid are 

 general in character, and 'at first one may 

 suspect rabies, or some form of poison, but the 

 coma that soon follows, and an autopsy, will re- 

 veal the true cause. The animal becomes dull, 

 with loss of appetite. Later, it begins to stagger 

 around in more or less of a circle, hence the old 



ESTBUS Ovis. 



a. Adult female. 



b. Adult male. 



