Stronghold for dogs Body weightVolume (ml)Potency (mg/ml)TotalSelamectin(mg) Up to 5 lbs (2.3 kg)0.256015 5.1-10 lbs (2.4-4.5 kg)0.2512030 10.1-20 lbs (4.6-9 kg)0.512060 20.1-40 lbs (9.1-18 kg)1.0120120 40.1-85 lbs (18.1-38.5 kg)2.0120240 ...