Advantage Multi for Cats is a topical solution. See steps below for how to apply. Step 1: Remove one dose applicator tube from the package. While holding the tube in an upright position, remove the cap from the tube. Step 2: Turn the cap over and push the other end of the cap onto the tip of the tube. Twist the cap to break the seal, and then remove the cap from the tube. Step 3: Part the hair on the back of the cat's neck at the base of the head until the skin is visible. Step 4: Place the tip of the tube on the skin and apply the entire contents directly on the exposed skin. Lift the tube away from the skin before releasing pressure on the tube.

Talk to your veterinarian about any heartworm testing that is recommended before starting your pet on a heartworm prevention program.