Penguins are reliant on a waterproof plumage to survive. The moult in Yellow Eyed Penguins is a seasonal process that occurs once a year, during which the animals go through fattening and fasting periods and high levels of stress to achieve the full replacement of old feathers. The plumage replacement takes three to four weeks, which penguins spend sitting ashore unable to feed. Although hormonal induction of moult has been achieved in chickens and other species, until now successful results have not been achieved in penguins. Four juvenile Yellow Eyed Penguins that were being prepared for release in a rehabilitation centre were referred to Wildbase for treatment following feather breakage and various degrees of pododermatitis. The four Yellow Eyed Penguins had a full physical examination including radiographs, bloods and the collection of faecal samples to assess their health. The pododermatitis was treated with serial debridement and bandaging under anaesthesia. The damaged feathers were plucked over several procedures, however the results were poor. In a rehabilitation setting, it is not feasible to keep penguins in captivity until the next natural moult occurs which could be 10 to 12 months. Complete moult was induced and achieved by oral supplementation of fresh beef thyroid. The induction of the moult was complete at around fourteen days following the treatment. The Yellow Eyed Penguins replaced their entire plumage successfully and their waterproofing was adequate, allowing release back into the wild.