No idea on the ducks but for a 200 to 220 pound man it is 2ml every twelve hours as a preventative or 4ml after showing symptoms. Nudge, nudge, wink, wink.This is very helpful ... but I was wondering how I might use this product in the drinking water for 7 ducks? Any advice ... for an aging 77 year old woman who has it for chasing 7 ducks around the pen? Pleeze.