The medicine works not by totally eradicating heartworms in the host animal, but by eliminating only the worms on tissue stage, stalling their development into the harmful bodies. (diamondpup.com)
Heartworm preventative for large dogs The ivermectin in Tri-Heart Plus for Dogs 51 - 100 lbs, 6 Month (Brown) is a broad - spectrum antiparasitic that kills heartworm larvae in the tissue stage. (vetdepot.com)
The ivermectin in Heartgard pet meds is a broad - spectrum antiparasitic that kills heartworm larvae in the tissue stage. (vetdepot.com)