THE DOG AS A CARRIER OF PAEASITES 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 
mentioned follow, 
culiar in that the 
tapeworms already 
It is, however, pe- 
intermediate stage, 
£- 
Fig. 9. — Twnia Kydatlgena, the 
adult tapeworm from the in- 
testine of the dog. Natural 
size (after Stiles). 
