Prevent heartworm disease and control ear mites in cats. Advantage Multi for Cats is a once a month topical solution used for the prevention of heartworm disease, kill adult fleas, treat flea infestation and treat and control ear mites and intestinal parasites including hookworm and roundworm in cats and kittens 9 weeks of age or older and weighing 2 lbs or more. What now: Check for an email from “customercare@allivet.com”. I didn't see my email, what do I do?: While your email should arrive instantly, please allow your email provider up to 25 minutes to deliver it.