Heartgard Plus Is The #1 Choice Of Veterinarians For Heartworm Disease Prevention! Only Heartgard Plus Comes In A Real-beef Chewable That Dogs Love. Heartgard Plus Also Treats And Controls Roundworms And Hookworms. It Is Approved For Use In Puppies As Young As 6 Weeks, Small Dogs Regardless Of Weight, Pregnant Or Breeding Bitches, Stud Dogs, And Collies.