my cat is suddenly chewing on things

For the last couple of weeks, Floco has been chewing on things, like my book covers and especially my husband's office chair (just the arms, which are soft and chewy, kind of). He's 13 months, so I know he can't be teething. The last time he and his brother did this, was when they were teething. His brother is not doing this now, just him.

I wonder if he is just bored and in a "chewy" mood, or if there could be something wrong with his teeth/gums. The vet pointed out recently that his brother has some mild gengivitis, so maybe he does too? Any ideas?

I don't think the gingivitis and the chewing are related. You may have something on the boredom issue. That could be solved with more interactive playtime. But then, maybe you just have a "chewer". I have one that likes to chew on plastic and I just have to keep the things she likes to chew out of reach. You might try putting something bad tasting like bitter apple or lemon juice on things, but the drawback of those is that usually they're effective only as long as they're damp.