THE DOG AS A CARRIER OF PARASITES AND DISEASE. 



15 



animal in which the bladder worm oc- 

 curred, and will give rise to a large tape- 

 worm, which may attain a length of 5 

 meters, or about 16 feet. 



Extensive burrowing of the parasites 

 in the substance of the liver during the 

 early period of the bladder-worm devel- 

 opment may cause serious damage, and 

 in cases of heavy infestation may result 

 in the death of the animal. Bacterial in- 

 fection may complicate the parasitic in- 

 vasion. In the United States, flocks of 

 sheep in which this parasite is not pres- 

 ent are rare, and a high percentage of liv- 

 ers, especially lamb livers, are condemned 

 in abattoirs under Government inspection 

 because of infestation with this parasite. 



Prevention calls for a proper disposal 

 of the viscera of slaughtered animals 

 with a view to keeping the viscera, un- 

 less first properly cooked, away from 

 dogs. It also calls for a routine tape- 

 worm treatment for dogs, an adequate 

 knowledge and supervision of the food 

 and feeding habits of dogs, and the elim- 

 ination of the dog without a responsible 



owner. 



TAPEWORMS. ROUNDWORMS, ETC. 



Double-pored tapeworm. — Of the nu- 

 merous species of tapeworm occurring in 

 the dog, many of them not mentioned in 

 this paper because they do not have a 

 larval stage or bladder worm in man or 

 stock, one species may occur in man in 

 the form of the adult tapeworm. This 

 species, commonly known as the double- 

 pored tapeworm {Dipylidium caninum) , 

 has a life history which follows the same 

 general plan of alternation, from a tape- 

 worm in the dog to a larval tapeworm 

 in an intermediate host and back to 

 the dog, that the tapeworms already 

 mentioned follow. It is, however, pe- 

 culiar in that the intermediate stage, 



.'•"la i ^ 



Fig. 9. — TcBnia hydaUgena, the 

 adult tapeworm from the in- 

 testine of tlie dog. Natural 

 size (after Stiles). 



