Iverhart Plus by Virbac, is a pork liver flavored chewable that contains an active ingredients that’s veterinarian recommended. Iverhart Plus is guaranteed to protect your dog from potentially deadly parasites: Heartworms, Roundworms, and Hookworms. It may be given to puppies as young as 6 weeks and is safe for pregnant or nursing dogs. A monthly dose of Iverhart Plus is all it takes to protect your dog from heartworm disease.