A thriving calf is a healthy calf – animal health is the foundation of any successful calf-rearing enterprise. But even if we tick every box on the optimum health checklist, chances are that, at some point during the rearing phase, sickness will strike. Here, the rearer’s own diagnostic skills come into play. An astute rearer will easily identify a poorly calf based on visual signs. But, at this point, an antibiotic is the likely remedy. In a society where antimicrobial resistance is a growing concern, is there scope to nip illness in the bud before it reaches this point?