Smallest dog is 20 lbs, largest is 80 lbs. I am having a hard time finding out how to dose out Ivermectin. It's costing us $180/MONTH to use Trifexis. So...I googled and found this, does this seem accurate? 1) Take 1 ml (10 mg) of Ivomec***65533; 1% and dilute it to 10 ml total volume which gives a concentration of 10 mg in 10ml solution. Propylene glycol is readily available so it may be used: 1 ml Ivomec***65533; 1% Inj. + 9 ml propylene glycol = 10 ml diluted solution with a concentration of 10 milligrams / 10ml which is the same as 10,000 micrograms / 10ml or 1,000 micrograms per 1 milliliter since 1 milligram = 1,000 micrograms. Label this: ***65533;ivermectin 1,000 mcg / 1ml dilution***65533; and write the date on the label of when it was prepared. 2) The dose range of ivermectin for dogs is 0.003-0.006 milligrams/kg body weight (1kg=2.2 lb) or 3-6 micrograms/kg of body weight. All calculations below use the higher dose of 6 micrograms / kg of body weight or 2.72 micrograms / pound of body weight. 3) Therefore a 100# dog (45.45kg) needs a 272 mcg dose: 45.45 kg x 6 mcg/kg = 272 mcg dose 4) The diluted solution prepared in step #1 contains 10,000 mcg / 10 ml or 1,000 mcg / 1 ml or 100 mcg / 0.1 ml therefore the dose in step #3 can easily be calculated: 272 mcg will be contained in 0.272 ml of the dilution prepared in step #1 which can accurately be measured using a 1 ml insulin or TB syringe which is graduated in tenths of a milliliter (0.1, 0.2, 0.3 ml), and which has 10 markings between each increment of 0.1, 0.2, etc. The 0.272 ml dose is measured by drawing up an amount past the 0.2 ml mark plus 7 of the smaller markings almost to the 0.3 ml mark. 5) Using the following formula, a proper dose can be calculated for any dog whose body weight is known: _______ Weight of dog in pounds X dose of 2.72 micrograms per pound of body weight/1000 mcg per ml ivermectin dilution prepared in step #1 = dose in milliliters of dilution from step #1 Examples: A dog weighs 77 pounds so 77 x 2.72/1000 = 0.21 ml of dilution given in food once a month A dog weighs 125 pounds so 125 x 2.72/1000 = 0.34 ml of the dilution given in food once a month A dog weighs 12 pounds so 12 x 2.72/1000 = 0.03 ml of the dilution given in food once a month I would use the diluted solution simply because of the 10 fold less chance of error. Measuring 0.21 ml is easily possible while measuring 0.021 ml is prone to error. I would prepare the dilution fresh each season and discard any unused diluted solution at the end of the season. I have read that ivermectin is photolabile meaning it is destroyed by light so both it and the dilution should be stored in a cool, dark place at or below room temperature. It does not seem necessary to refrigerate the solution or the diluted solution. Yay or nay??