334 MANUAL OF EQUINE MEDICINE. 



egg breaks its shell and obtains its liberty. The immature 

 worm or embryo now passes through the intestinal wall and 

 wanders about until it arrives at a spot suitable for its 

 development into a perfect cyst. 



In this condition it will remain and perish, unless its host 

 dies or is killed. In the latter case it may gain access to 

 the intestinal canal of another host fitted for its further 

 existence, and in this case the scolex fixes on to the gut, 

 and the proglottides slowly develoj). 



It is very rare that the same animal serves as host both 

 for cyst and adult worm. 



Some tapeworms have hooks on their proboscides, others 

 are devoid of hooks. 



The chief tapeworms of the horse are : 



(A.) Tsenia Plicata. — This worm varies in length from six 

 inches to three feet. It has a short neck, and a body com- 

 posed of narrow segments, which give to the worm a blunt 

 serrated margin. Its habitat is usually the small intestine, 

 although it has occasionally been found in the stomach. 

 Of all equine cestodes it is the largest. 



(B. ) Taenia Perfoliata. — The length of this parasite is from 

 one to three inches ; it may, however, be five inches long. 

 It may be recognised by the two fleshy lobes, the almost indis- 

 tinct neck, and the visible narrowing of the segments as they 

 near the tail. The favourite habitat is the caecum and colon, 

 where this worm is sometimes found in large numbers. 

 Of equine cestodes, it is the most common, and may give 

 rise to serious disturbance. 



(C.) Taenia Mamillana. — This member of the group is 

 about half an inch long, and has no obvious neck, no 

 lobes, and is made up of wedge-shaped segments with pro- 

 minent reproductive papilla^. It infests the colon. 



Treatment of Tapeworms. — Such drugs as oil of male 

 fern, absinthe oil, or oil of turpentine, should be given. 



