Hi all...I have a question. My little guy Peppe will be going to the Vet next week, and I need to get him his heartworm meds. What product do you all use??? Are there any differences? What do you think is best? Right now he is too little to use it because he only weighs 1.6 lbs I was told that he needs to be at least 2 lbs. to use the meds. Any suggestions would be great.