[Ellie May]

Yes, he is old enough and heartworm meds shouldn't be split, so that is the appropriate size.

I can't help you on the other one because I'd never put flea meds that low down. They can lick it off and then you will have a toxicity problem. I'd read the instructions that it came with or go to the Advantix site. Those types of meds are supposed to go between the shoulders only.