: Even for dogs on year-round prevention, annual testing is recommended to ensure the product is working and that no doses were missed or spit out. Where to Purchase Heartworm in Dogs

: Dogs must test negative before starting or renewing a prescription, as giving medication to an infected dog can cause severe, life-threatening reactions.

: The FDA classifies all heartworm preventatives as prescription-only drugs.

Heartworm prevention is a lifelong commitment that requires a veterinarian's prescription and regular testing. While online pharmacies offer convenience, purchasing through your vet ensures product safety and often includes manufacturer guarantees that internet retailers cannot provide. Buying Requirements