iO FENBENDER 100iO Fenbender is a ready to use broad spectrum oral worm drench for control of benzimidazole sensitive mature and immature roundworms and lungworm in cattle, and for the control of large strongyles, small strongyles, ascarids and pinworms in horses. Active Constituent: 100 g L FENBENDAZOLE Dose Rates & Administration Instructions: CATTLE: 7. 5 mg kg Fenbendazole or 3 mL per 40 kg bodyweight. Cattle in excess of 680 kg to be dosed at 3 mL per 40 kg