What Does Fenbendazole 500Mg Do for Dogs? Fenbendazole 500Mg is a widely used deworming medicine for dogs. It belongs to the benzimidazole class of antiparasitic drugs and is commonly prescribed by veterinarians to treat a variety of intestinal worms and parasites. This medication works by disrupting the energy metabolism of parasites, causing them to die and be removed naturally from the dog’s body. Fenbendazole is considered...