Disorders of Keratinization in a Group of Related Captive Koalas (Phascolarctos cinereus), with a Review of Other Skin Conditions in Koalas

Paul Canfield1, B.V.Sc., Ph.D., Alison Spencer1, B.Sc., B.Vet.Med., William Hartley2, M.V.Sc., D.Sc., Derek Spielman2, M.V.Sc., Larry Vogelnest2, B.V.Sc., and Frances Hulst2, B.V.Sc.


1Department of Veterinary Pathology, University of Sydney, New South Wales 2006, Australia

2Veterinary Quarantine Centre, Taronga Zoo, Mosman, New South Wales 2088, Australia


Disorders of keratinization were detected in a group of related koalas held captive at the Taronga Zoo, Sydney, Australia. One female koala had volar hyperkeratosis and diffuse seborrhea characterized by cutaneous horns. Both its female sibling and a female parent had diffuse seborrhea. The female grandparent had a diffuse seborrhea characterized by papules and nodules. Records of unrelated koalas held captive at the Taronga Zoo revealed a female with facial and limb alopecia and scaliness of unknown cause and two koalas with dermatophytosis. Examination of records kept in the Non-Domestic Animal Registry at the Taronga Zoo revealed three further cases of idiopathic disorders of keratinization (volar hyperkeratosis, "nodular dermatosis," and diffuse seborrhea) in unrelated free-living and captive koalas. Therefore, the significance of the familial nature of the disorders of keratinization in the koalas held at the Taronga Zoo was questionable. The skin changes present in the koalas with idiopathic disorders of keratinization were distinct from skin changes present in koalas with sarcoptic mange and dermatophyte infection.