The small-animal vet version of Heartguard is a topical skin application, the chemicals are dissolved in alcohol, or so it smells. And it's more like $25 a dose at this point. That's why I buy it from the UK, they cost a lot less (I use the UK version of Revolution, it's called Stronghold over there, and to order you need to know how much your dog weighs in kilos, not pounds. But the clue is the color of the box; my two largest dogs get the Teal box, US or UK.)