Fenbendazole is a medication used in veterinary medicine to treat a wide variety of parasites in dogs, cats, horses, cattle and other large animals. It is a member of the benzimidazole group and has a very broad spectrum anthelmintic effect. It is particularly useful in treating giardia, roundworms, hookworms, whipworms and the Taenia genus of tapeworms. It can also be helpful in preventing and treating pinworms in puppies.

It is a moderate-acting medication that usually stops working within a few days, although it may take longer in pets with liver or kidney disease. Your veterinarian may recommend a fecal examination after your pet has been treated to ensure that all internal parasites have been killed.

In addition to its anthelmintic effects, fenbendazole has demonstrated antitumor properties in tumor-bearing mice. In a study in which unirradiated tumors were administered to nude mice, treatment with fenbendazole significantly reduced the size of the tumors and their vascularity. It also induced death of the tumor cells, and inhibited the proliferation of nasopharyngeal carcinoma and nonsmall cell lung cancer cell lines.

This medication is available through your veterinarian as a compounded tablet or capsule, typically for dogs and cats with a specific reason. Compounded medications are created by a veterinarian or a licensed pharmacist to best meet your pet’s unique needs, such as if the medication is not commercially available in capsule form, the dosage strength is not available commercially, or your pet has an allergy to an ingredient contained in an FDA-approved medication. For this medication, a prescription from your vet is required. fenbendazole capsules