For the treatment and prophylactic control of all economically important gastrointestinal roundworm infections in cattle weighing between 100 and 300 kg at the time of administration. Also as an aid in control of parasitic bronchitis (lungworm infection).The Panacur Bolus is designed to release fenbendazole continuously in the reticulo-rumen of cattle for up to 140 days (20 weeks). When administered later in the season, the intraruminal device treats established parasitic infections and continues to control parasitic gastroenteritis up to 140 days after administration. This period may be reduced if cattle are moved to heavily infected pasture. Lungworm The Panacur Bolus aids in the control of parasitic bronchitis caused by the lungworm Dictyocaulus viviparus.