I am unclear on dosing per lb for heartworms. I know that the Ivomec needs to be cut or diluted. My dogs are 3-10 lbs. What is the best liquid to do this with? If I dilute my Ivomec with equal part liquid, how much do I dose monthly per pound? I have also heard of using the Ivomec topically on the back and rubbing into the skin for heartworm prevention? Is anyone familiar with this type of topical application? How much Ivomec is used per pound for topical application and is it even effective for heartworm prevention in dogs?