134 ANIMAL PARASITES IN THE STOMACH 



The development of the tapeworm is as follows: The eggs 

 with the segments of the adult worm which inhabits the 

 intestines are voided with the feces and thus reach the out- 

 side world. There they are taken up by a second host, in 

 the stomach of which the embryo, often provided with hooks, 

 is hatched. These embryos penetrate the bowel wall and 

 mter the bloodvessels, and are carried to distant organs, 

 such as the muscles, brain, lungs, etc., developing in these 

 organs cysts. If organs containing such cysts are ingested 

 by animals which would form the proper host there develops 

 in the intestine a tapeworm. The tapeworm is provided with 

 a head or scolex to which is attached a number of segments 

 or colonies that, when ripe, contain the fertile egg of the 

 tapeworm. 



Varieties. — Each of the domesticated animals has species 

 of tapeworms peculiar to itself. 

 Horse: 1. Taenia perfoliata. 



2. Taenia plicata. 



3. Taenia mamillana. 

 Ox: 1. Tsenia expansa. 



2. Taenia denticulata. 



3. Tsenia alba. 

 Sheep: 1. Tsenia expansa. 



2. Taenia ovilla. 



3. Tsenia alba. 



4. Tsenia fimbriata. 



Symptoms. — Tapeworms, unless present in large number, 

 rarely produce symptoms. For instance, over 50 per cent, 

 of the dogs harbor tapeworms, particularly the Taenia cucum- 

 erina. On the other hand, tapeworms sometimes cause 

 chronic intestinal catarrh (diarrhea alternating with con- 

 stipation, icterus, and eventually anemia). In horses colic 

 may be caused by them. In sheep they induce chronic 

 bowel catarrh, anemia, and often fatal cachexia. In rare 

 instances a perforative peritonitis may be due to tapeworms. 



Diagnosis. — Tseniasis can be diagnosed positively only by an 

 examination of the feces in which will be found the segments 

 or eggs of the tapeworm. In sheep a diagnosis may be made 

 by a necropsy. 



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