Aust Vet J Vol 76, No 11, November 1998 743 Skin disease affecting the conservation of the western swamp tortoise (Pseudemydura umbrina) JM LADYMAN a , G KUCHLING b , D BURFORD c , W BOARDMAN b and SR RAIDAL d Objective To review the present position of the western swamp tortoise (Pseudemydura umbrina) as an endangered species and significant health issues affecting efforts to save it from extinction. Procedure A retrospective analysis of the husbandry, hospital and pathology records of the western swamp tortoise captive breeding program at Perth Zoo. Results In 1987 a captive breeding project was devel- oped to prevent the extinction of the western swamp tortoise but an outbreak of a necrotising dermatitis in 1989 threatened the survival of the captive bred hatchlings. Less severe outbreaks occurred in 1990 and 1993, with isolated cases in between. Of 283 tortoises that were born in captivity or came into captivity from the wild, 37 (13.1%) were affected, comprising 37% of all males, 26% of all females and 13% of animals of unknown gender. Of the affected animals, 70% were less than 2 years of age and 29% were older. Males were 1.6 times more likely to be infected than females but this difference was not statistically significant (P = 0.27). Culture of the lesions consistently yielded unidentified Pseudomonas sp. Conclusion Improved husbandry, such as strict mainte- nance of water quality and temperature conditions similar to that of the animal’s natural habitat, and monitoring the health of individual tortoises have successfully controlled skin disease in the captive breeding of the western swamp tortoise. Aust Vet J 1998;76:743-745 Key words: Western swamp tortoise, species conservation, necrotising dermatitis, Pseudomonas sp. UWA University of Western Australia CALM Western Australian Department of Conservation and Land Management WWF World Wide Fund for Nature ANPWS Australian National Parks and Wildlife Service T he short-necked or western swamp tortoise (Pseudemydura umbrina) is a critically endangered species of short-necked freshwater tortoise that has only two known populations remaining in the wild, both on the Swan River coastal plain of Western Australia. The population suffered a dramatic decline in the 1970s and 1980s, and in the mid-1980s comprised 17 in captivity and approximately 30 in the wild. 1 Factors that contributed to this critically endangered status included very small geographic range, the loss of habitat to agriculture, industry or building, the restriction of habitat protection to only two small nature reserves, increasing aridity of the remaining habitat, low fecundity, and predation, particu- larly by the European red fox. 1 The current range includes two protected reserves near Bullsbrook and scattered localities in a 3 to 5 km wide strip of the Swan coastal plain, with largely alluvial soils. 1 The species only inhabits ephemeral swamps that have suitable sites nearby for aestivation. 1 The swamps are on clay or sand over clay soils and must contain diverse invertebrate species for feed. 1 When the swamps dry out in summer the tortoises aestivate in natural tunnels in the clay or in holes underneath vegetation or logs. 1 They terminate aestivation when the swamps fill at the begin- ning of winter. The mating season commences after the summer aestivation, between May and July depending on rainfall, and continues until September. The gestation period is 5 to 7 weeks, and two to six hard-shelled eggs are laid in one clutch between October and December 1 and hatch after 180 to 190 days. 2 The tortoise reaches reproductive size (male about 12 cm, female 11 cm) at 7 to 20 years of age and may have a life-span of 60 to 70 years or more. 1 This longevity mitigates, to an extent, their low fecun- dity and slow growth. The tortoise is strictly carnivorous and mainly eats crustaceans, tadpoles and aquatic insects. 3 A high dietary biomass is required in spring, when the tortoises need to be in good breeding condition. 4 Conservation measures Shortly after the western swamp tortoise was rediscovered, studies on the species commenced and Dr David Ride, then Director of the Western Australian Museum, coordinated field searches and kept a captive colony at his home. This colony was transferred to Perth Zoo in 1964. 1,5 In 1962 nature reserves were created by the Government, aided by a public appeal for funds. These reserves protected much of the remaining habitat of the species and are vested in the National Parks and Nature Conservation Authority and managed by CALM. The captive breeding program at Perth Zoo was attempted in a low-key, non-interventionist way from 1964 until 1979. The success was poor. Only 4 animals are still alive of the 26 that were hatched between 1966 and 1977. 1,6 In 1979 the three remaining adult females from the Zoo population were trans- ferred to the Western Australian Wildlife Research Centre, where more intensive husbandry was practiced, including inter- ventionist methods of obtaining and incubating eggs. Despite the practice of radiographing females during the breeding season and inducing oviposition in gravid females by injections of oxytocin, no eggs were produced between 1981 and 1986. 6 In 1987 a captive breeding project was developed for the species and involved Perth Zoo, UWA, CALM, WWF, ANPWS and the Western Australian Nature Conservation and National Parks Trust. 1,6 The project was designed and carried out by Dr G Kuchling, of the Zoology Department, UWA. In 1991 the a Parap Veterinary Hospital, 42 Parap Rd, Parap, Northern Territory 0820 b Department of Zoology, The University of Western Australia, Western Australia 6907 c Perth Zoo, South Perth, Western Australia 6151 d Division of Veterinary and Biomedical Sciences, Murdoch University, Western Australia 6150