Efficacy of praziquantel against immature Echinococcus multilocularis in dogs and cats.

Efficacy of an injectable formulation of praziquantel (given IM at a dosage of 5 mg/kg of body weight) against immature Echinococcus multilocularis was studied in 18 experimentally infected dogs and 22 experimentally infected cats. There were no worms recovered at necropsy from any of the treated hosts. However, whereas E multilocularis worms were recovered from all nontreated control dogs (n = 9; min-max 15-1,840, mean 483), such tapeworms were recovered from only k6 of the 11 nontreated control cats (min-max 2-820; overall mean 123.4). The study demonstrates 100% clearance of E multilocularis by praziquantel in experimentally infected dogs and cats, and shows that cats are not as suitable as experimental hosts for this parasite as are dogs.