Panacur, by Intervet, is a broad-spectrum anthelmintic (deworming medication) that contains fenbendazole as the active ingredient. It is used to treat both immature and mature roundworms as well as hookworms, whipworms, tapeworms, intestinal flukes and the protozoa Giardia in dogs. Fenbendazole is a benzimidizole-class dewormer.
Recommended dosage is 100 milligrams per kilogram (about 2.2 pounds) of body weight for routine treatment. For dogs weighing over 30 kilos (65 pounds), an extra one-half gram of fenbendazole is required for each five kilos (11 pounds) of additional body weight. Panacur powder is administered over three days by sprinkling a packet with the required amount over the food. Repeat treatment is recommended every three to six months or more. Dogs in kennels may require treatment every six to eight weeks.
Fenbendazole is considered quite safe. Even at high doses, it is usually non-toxic. There is small risk of anaphylactic shock from treating a heavy worm infestation, but this is due to the parasites dying off in very large numbers. Vomiting may occur after treatment, but this is rare. Dead worms may be observed in a dog's stool after administering. Allergic reaction may occur. Panacur should not be used in a dog with a known hypersensitivity to fenbendazole. (http://www.petplace.com/drug-library/fenbendazole-panacur/page1.aspx) (See Reference 2 -- answer for fourth question on page.)
Your dog may have worms and show no outward signs or symptoms. A bloated belly from heavy worm infections may be seen in young puppies. Large numbers of Toxocara canis roundworms may be lethal and can even be spread to humans through contact with infected feces. A regular deworming program is a vital aspect of your dog's health and well-being.
Before you use Panacur, or any deworming medication, bring a stool sample from your dog to your vet. Ideally, the sample should be collected and brought to the vet the same day your dog has left it. A teaspoon-sized sample is sufficient for testing. Turn a small plastic baggie inside out and place it over your hand and collect the sample, turning it inside out once again, being careful not to pick up any dirt or grass with it. After your veterinarian has determined the type and level of worm infection, you may then administer Panacur according to your veterinarian's instructions.
Panacur is available in the United States without a prescription, either online or at your veterinarian.