Intestinal Parasites in Dogs. 301 



Taenia Serrata. Serrated tape-worm. This inhabits the 

 small intestine of the dog which obtains it by eating rabbits and 

 hares. When discharging ripe segments it may measure from 20 

 to 60 inches — usually 40 inches. Head is slightly broader than 

 the neck, tetragonal with a sucker on each angle. Proboscis 

 retractile with two rows of 34 to 38 hooks, one row long (230 fj. 

 to 260 /u.) and one short (125 jn to 160 j«.), and each bearing a pro- 

 cess or guard. Segments at neck mere transverse lines; caudal 

 segments 3 times as long as broad (5 by 15 mm.). Genital 

 orifice on projecting marginal elevation. Oviducts lengthy, 

 branched (8 or 10). Ova slightly ovoid. 



The cysticercus pisiformis, the larval form, found in the 

 peritoneum of rabbits and hares, the cyst having a variable size, 

 on an average about }^ inch and containing the head and neck 

 of the taenia, which is withdrawn into the sack through an orifice 

 in its wall, as a finger of a glove within itself. By feeding a ripe 

 segment of the T. serrata to a rabbit these are developed in the 

 liver, iu which, in fifteen or twenty days they may be found as 

 small, white, worm-like bodies i to 4 mm. in length. These 

 proscolices mostly migrate in to the peritoneum and are found at- 

 tached to the viscera, the parietes, the mesentery or omentum as 

 scolices. The rodent host, being devoured by the dog, they de- 

 velop in his intestines into strobila by dropping the caudal cyst. 

 In 50 days these may be 5 to 8 inches in length ; in 60 days about 

 20 inches ; in 150 days from 4 to 5 feet and shedding ripe seg- 

 ments. The rabbit is usually infested by eating vegetation or 

 drinking water which contains the proglottis or ova derived from 

 the dog's faeces. The cysticercus has great vitality and though 

 dried up in the ti.ssues, it will show active vitality if put in tepid 

 water. 



Taenia Serialis : inhabits the small inte-stine of the dog, but 

 is much more rare than the taenia serrata. It may attain a length 

 of 15 to 25 inches. Head a little wider than the neck ; tetragonal 

 with 4 discs, and protractile proboscis with 26 to 32 hooks, each 

 furnished with a guard and having the handle as long as the 

 blade. Guard slightly bifid. The ripe segments are three times 

 as long as wide (4 by 12 mm.). Genital orifice marginal, pro- 

 jecting. Ova nearly round (34 ju, by 27 /«.). In its general char- 

 acters the worm resembles its near relative the tcEuia ccenurus. 



