Hi Pat,
I have a Baxter too - only he weighs 12 lbs! I remember asking my vet about the Heargard dose. I think it said 1 square per 10 lbs, and mine only weighed 4 lbs at the time. The vet said I should still use it. However, your little guy is really small. I'd give them a call just to verify that you should give him the whole thing. Your Baxter is a beautiful little boy!