Is it sensible to combine several veterinary medications in feedstuffs?

Several criteria need to be examined and evaluated to determine whether it is appropriate to combine several premix medications in feedstuffs. The com bination of bacterial and bacteriostatic substances is not appropriate as t hey interfere with one another. Tetracyclines and sulphonamides should not be used in combination as they ale active against the same spectrum of path ogens. The microbiological activity of tetracyclines is inactivated to a va rying degree by the cations of feedstuff ingredients such that their bioava ilability is reduced considerably. Resistance of pathogens has resulted in an unfavourable situation for tetracyclines. Sulphonamides without potentia ted action should riot he used without sensitivity screening because of the high rate of transmission of resistant organisms. The use of combination o f antimicrobials which are easily absorbed, such as tiamulin and amoxicilli n, and those which are not easily absorbed is justified against systemic an d enteric bacterial infection. Following the decision for a combination the rapy, clinical monitoring of the effect, including adverse reactions, is re quired involving the identification and characterisation of the pathogen, f or example by antibiogram, for specific chemotherapy.