Moth Feathers
Why dose with preventative medicine? Why not simply treat them as they come up (which would be rare for an indoor cat, unless it's in contact with other pets that go outside)?
Having fleas, lice, or other bugs is not pleasant for the animal. A lot of cats and dogs have flea allergies as well, so a couple flea bites can quickly make them miserable. For areas with a high risk of them getting parasites, it's best to use preventative care.
Out of the ones listed, Frontline is my favourite.
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