All of mine had begun heartworm preventative when I got them at 3 months.
Usually they are tested for heartworms prior to giving the preventative.
I used to half the dosage of the flea medicine, but never did that with the heartgard....you may want to ask the vet.
__________________ Deb, Reese, Reggie, Frazier, Libby, Sidney, & Bodie |