Micromelia in Little Penguins (Eudyptula minor)

Abstract

Two cases of unilateral micromelia are described in wild juvenile little penguins (Eudyptula minor). The first bird was found at San Remo, Phillip Island, Victoria, Australia. The bird's left flipper was reduced in length, and radiography demonstrated severe shortening and dysplasia of the humerus. The second bird was found having difficulty swimming off the coast near Fremantle, Western Australia. Clinical examination revealed that the bird was underweight (0.55 kg) but otherwise in good condition with subadult plumage and had probably only recently fledged from nearby Garden or Penguin Islands. The left wing was markedly reduced in size and had limited range of elbow and carpal joint movement but sensation and motor control were normal. Radiography demonstrated a severe reduction in size and distortion of the humerus and shortening and fusion of the ulna, radius, metacarpals, and phalanges. The furcula was asymmetrical because the left clavicle was slightly thinner and more radiolucent than the right and was also slightly deviated to the right side. Necropsy results of histopathologic examination revealed no other significant external abnormalities other than a mild focal heterophilic ulcerative proventriculitis from a mild burden of Contracaecum eudyptulae. Concentrations of heavy metals in kidney, liver, and brain were: cadmium, <6 mg/kg; mercury, <0.05 mg/kg; lead, <2 mg/kg; and selenium, 1.30 mg/kg. Possible causes of unilateral micromelia in these penguins are discussed.