Just gave my new cat a drontal feline pill yesterday and want to take her and her litter box out of quarantine so she can be with the other cats in the house. (She is a new cat to the house, had fleas so assume thats how she got the tape worm, she no longer has fleas as they were treated with advantage 10 days ago) she has been in quarantine pretty much since we got her 11 days ago cuz we saw she had fleas and didnt want the other cats in the household to get them. so there isnt much chance the other cats in the house need to be treated.
I also realize i need to give her another pill in 4 weeks but my main question was
Does any one have and idea how long drontal feline takes to erradicate the worm? Do I keep my cat in quarantine for 3 more weeks?
If your cat is free of fleas and all fleas in the house have been desposed of then it is fine to let her be with the rest of your pets. If she has tapeworms and is taking meds she is fine. Tapeworms are not contagious. The only way to get then is by digesting fleas or eating feces which I hope your cats don't do. It can take a few weeks before she stops passing the segments of the worm so don't be worried if they aren't gone right away. But just make sure you have settled your flea problem.
about a week