i use micatil quite a bit for cows and for calves over 200 lbs for respiratory problems. very seldom is a second dose required. 2 doses are the maximum. after that i go to baytril or to another drug, but not over 2 times with the micatil. you have to wait at least 72 hours after the first dose or you risk crippling the animal for life. that was why i stopped using it for baby calves, it was too easy to over dose and cripple one, they are very susceptible to micatil damage---for babies, I use baytril and a sustain 3 scour tablets, that seems to work great. Whatever you do, do not give yourself a shot of micatil, if you accidently do this, i think they say it takes 1/2 cc to throw yourself into a massive heart attack. that is why most of the time when i use micatil, i use it in the dart gun. if you give it by hand, make sure you have the animal totally restrained