Ivomec Pour On enters the bloodstream through the skin. Wormer is effective against mature and immature stages of internal and external parasites including roundworms, lungworms, grubs, mange mites, horn flies (for up to 28 days!) and biting and sucking lice backed by Merial's Product Satisfaction Guarantee! Contains 5 mg ivermectin per ml. Apply along back of animal at 5 ml pet 110 lb of body weight. Measuring cap makes dosing quick, easy and accurate. Not cleared for female dairy cattle of breeding age. 48 day slaughter withdrawal. Applicator gun needed for 2.5 ltr, 5 ltr & 20 ltr ONLY. Dosage 250 ml will treat 5,500lb, 1,000 ml will treat 22,000lb, 2.5 ltr will treat 55,000lb, 5 ltr will treat 110,000lb. IVOMEC Pour-On is also effective against the following external parasites: Horn flies, Cattle grubs, Chorioptic and Sarcoptic mange mites, Sucking and biting lice.