4 in 1

I use a solution of chlorine bleach to clean my lofts and chicken and pig houses. I clean them, then spray a diluted solution on EVERYTHING until it is soaking wet, then I let it dry. (I have room to transfer my birds and animals to other areas when it comes to cleaning, so they are not exposed to the bleach.)
I never use a "Catch all" medication, on advice from my vet. Prevent the problem, but if something arrives, treat the problem.
Years ago terramycin was the drug of choice for many people. But it was overused and used in an incorrect manner and the drug is no longer as effective as it was even 15 years ago.
As A Side Note: I get so mad when I see people saying, use this drug, use that drug, this drug is best an will kill anything, etc... But people do not tell you how to use it. If the manufacture recommends using it for five days, you need to use it for five days. Too many people use it for four days, because the animal is looking better and decide to save some money and not treat for the fifth day. This is what causes these virus and bacteria to become immune to the drug.
These companies spent millions of dollars researching their drugs and they want to make money off of them. If we misuse the drugs, they have to spend millions more to develop another drug, and in the end, we pay for it. Anyway, enough of my rant. Thanks.