Porcine ear necrosis (PEN), often referred to as ear-tip necrosis, is a familiar but challenging condition in nursery and early grower pigs. Lesions usually begin as redness and swelling at the ear tip and can progress to scabbing, necrosis and, in severe cases, loss of part of the ear. Although recognised for decades, uncertainty around the cause of PEN has limited effective prevention, with most control efforts focusing on managing risk factors rather than stopping the disease itself. New research has now provided the clearest evidence to date that PEN has a specific infectious cause, helping to explain its behaviour…