Fenbendazole is a broad-spectrum anthelmintic belonging to the benzimidazoles, effective against roundworms and, depending on the dose, also against some tapeworms (e.g. Moniezia spp) as well. It is ineffective against flukes (e.g. Fasciola hepatica adults) at the usual therapeutic dose. It is completely ineffective against external parasites. Oral administration is the rule. It is used massively in all kinds of livestock (mainly in drenches and feed additives), and abundantly in pets (often in tablets, pills, etc. or oral suspensions) and horses (mostly in oral pastes & gels). There are hundreds of generic brands worldwide, also in mixtures with other anthelmintics.
Beef and Dairy Cattle – 2.3 mg/lb (5 mg/kg) body weight for the treatment and control of: Lungworms: Adult Dictyocaulus viviparus; Stomach worms: Adult brown stomach worms (Ostertagia ostertagi), Adult and fourth stage larvae barberpole worms (Haemonchus contortus & H. placei), and Adult and fourth stage larvae small stomach worms (Trichostrongylus axei); Intestinal worms (Adult and fourth stage larvae): hookworms (Bunostomum phlebotomum), thread-necked intestinal worms (Nematodirus helvetianus), small intestinal worms (Cooperia punctata & C. oncophora), bankrupt worms (Trichostrongylus colubriformis), and nodular worms (Oesophagostomum radiatum).
Beef Cattle Only – 4.6 mg/lb (10 mg/kg) body weight for the treatment and control of: Stomach worms (4th stage inhibited larvae): Ostertagia ostertagi (Type II Ostertagiasis); Tapeworms: Moniezia benedeni.
Withdrawal Periods and Residue Warnings: Milk taken from cows during treatment and for 48 hours after the last treatment must not be used for human consumption. Cattle must not be slaughtered for human consumption within 8 days following last treatment with this drug product. Not for use in beef calves less than 2 months of age, dairy calves, and veal calves. A withdrawal period has not been established for this product in pre-ruminating calves
Administer orally. In beef and dairy cattle, the recommended dose of 2.3 mg/lb (5 mg/ kg) is achieved when 2.3 mL of the drug are given for each 100 lb of body weight. In beef cattle only, the recommended dose of 4.6 mg/lb (10 mg/kg) for treatment and control of Type II Ostertagiasis (4th stage inhibited larvae) or tapeworms is achieved when 4.6 mL of the drug is given for each 100 lb of body weight.
Dosing recommendations for antiparasitics depend on national regulations. National regulatory authorities determine whether a product is approved for a given indication, i.e. use on a particular host at a specific dose and against a specific parasite.