Hi, I'm so glad to hear that you were able to get 3 of your cats spayed and dewormed. I have 6 cats indoor only cats and yes even they can get fleas because they can jump on me from being outside. I've been buying advantage for the largest dogs over 55 lbs and then I measure the right amount for my cats. I've never had a problem since.

For cats under 10lbs they only need 0.4ml and for cats over 10lbs they only need 0.8ml. One tube of advantage for large dogs comes in a tubes that are 4.0ml so I can give each cat several doses of it from one tube. As far as I know there aren't any experation dates so I don't know what the shelf life would be. I've also been buying mine online and or at a pet store. It seems to be much cheaper than buying it through your vet. Good luck.