I'm sort of sceptical about them, and haven't used them. If your cat is getting a well-balanced diet, e.g. a good premium food (ours gets a combination of different brands, both wet and dry, and for the most part organic), why should he/she need vitamin supplements? I'd be afraid of an overdose.
Absolutely concur - my concern as well. I was on the phone w/the vet while waiting to see any response from the vast feline universe out there. She said the organic ones might be better, 1/2 dose of normal as to not overload and call her in a week. I think this might be ok. It will be interesting to see who else responds to this and what thier experiences are, too........