Has Jackson tried Heartgard Plus chewables, or was it some other brand? Joey and Ralphie go nuts over them, although I’ve read of other dogs hating them. I think the Iverheart plus would be a good choice, it’s just the generic form of Heartgard and it’s cheaper. It comes in a chewable tablet, but it’s looks like it’s much smaller than the Heartgard plus, so it would be easy to cover it in a little cheese. The only reason I'm using the heartgard plus is they love them so, if I had to disguise them, I'd use a cheaper version.
Iverhart Plus® Tablets (Generic)