Zuprevo is nothing short of a miracle antibiotic for deer! I've been using since July and have saved animals that should be dead right now from pneumonia all winter from a 3 year old buck who was to the point of almost falling down, staggering and gasping for air to fawns with bloody frozen drool and pumping stomachs. Its residual is 28 days in the system, but probably not for deer with their high metabolism (14 days for Draxxin) and it hits the lungs within 45 minutes. I've never saved such down and out deer before Zuprevo and its been with one strong single dose. Wouldn't be without it right now. All treated and saved have been run thru the working facility and given a very strong dose, but Zuprevo is very dartable since it is extremely watery.