I have used Zerokrim Plus Chewable Tablet (Fenbendazole) to de-worm my dogs including one who had lung worm. This stuff works on dogs both to kill worms and as a preventative. One teaspoon per every 20 pounds of weight of the dog. As a preventative do this once a day for 3 consecutive days. To kill the worms, once a day for 14 days, I mix it with wet cat food because the strong smell of the cat food hides the smell of the medicine.