We we to a jackpot show this weekend and this morning all of our calves have green, snotty noses. My husband took the kids to school then stopped at the vet and came home with a 2 boxes of Sustain III. I had to stop him from giving it because my kids attended a show cattle work shop a while back and the speaker, a professor at tamu covered a lot on drug withdrawals/withholds and advised not to use sulfa bolus 100 days before any Texas major as an extra precaution against possible tissue residue. He said the sulfa bolus hangs around in the kidneys a long time. I have spent the last 2 hours looking up info online and the only thing I found online is as long as you follow the dosing instructions and give the correct amount for the weight of the animal you have to exceed 2 doses in 72 hours for it to leave tissue residue. We are waiting on a call back from our vet to see if there is another way for us to go with this. All of my web searching kept leading back to old threads on here so I searched on here too. There is a mountain of info on slaughter withholds but not much on residue elimination. I know this is a hot topic on here and I'm not trying to start a war, I would just like to know the protocol on this from people that are long timers at the shows here in Texas. I'm worried my vet may not realize how strict the testing policy is and just the presence of tissue residue can result in a dq. Thank you in advance.