Abstract
The platypus (Ornithorhynchus anatinus) is the only extant species in the Family Ornithorhynchidae. Together with the echidnas, the platypus belongs to the Order Monotremata, the egg-laying mammals. The monotremes possess a common opening, the cloaca, for the reproductive, urinary and digestive systems. They exhibit several reptilian, avian and mammalian characteristics in their physiology, reproduction and anatomy. The platypus is one of a few venomous mammals, the males having a venom gland, connected by a duct to a hollow spur projecting medially from the tarsus (Grant 1989; Booth 2008).
Platypuses occur in freshwater streams and lakes in a wide range of habitats along the eastern seaboard of Australia and Tasmania. They are highly specialised, semi-aquatic, semi-fossorial, opportunistic benthic carnivores. In the wild they mainly eat aquatic insect larvae and small, soft-shelled crustaceans, but they will also eat small fish, frogs and worms. They are solitary and mainly crepuscular to nocturnal (Booth 2008). They are IUCN red list category 'least concern,' but are vulnerable to environmental degradation and pollution.
The platypus has a streamlined body that is compressed dorsoventrally and is covered by fur except for the bill and feet. There are two pairs of pentadactyl limbs, with claws and webbing on the digits of the manus and pes. The pes is turned caudolaterally. Webbing on the fore limbs extends beyond the claws to form fan-shaped paddles for swimming (Grant 1989; Booth 2008).
Injured or debilitated wild platypus may be rescued and presented to veterinarians for treatment. Careful assessment and management are required to ensure successful treatment and rehabilitation. A few are also held in zoos in Australia. Once adapted to a captive environment they are generally hardy. However, the successful maintenance of platypuses in either temporary or permanent care requires specialised housing, husbandry and diet. Although there has been some success, platypuses are generally difficult to breed in captivity.
Anaesthesia is required for most clinical procedures. Platypuses are surprisingly strong and their skin is loose making them difficult to handle. Mature males are dangerous and should only be captured and handled by experienced people. Anaesthesia with isoflurane in oxygen is straightforward and safe. Intubation is impossible. Clinical techniques and procedures require an understanding of the unique anatomy and physiology of platypuses. Venipuncture is achieved via a venous sinus that runs along the rostral margin of the bill. Haematology and serum chemistry reference ranges are available. Intravenous catheterisation is difficult. Urine is gelatinous and can be collected via ultrasound-guided cystocentesis. There are limited data on urinalysis. Radiography and ultrasonography are valuable diagnostic tools.
Only a small number of infectious agents and parasites have been reported from platypuses (Whittington 1992; Booth 2008). Many are non-pathogenic. Non-infectious diseases other from trauma and failure to thrive are also uncommon. There is limited information on therapeutics. Drug selection and dose rates are usually extrapolated from small domestic animal medicine with apparent therapeutic effect and no adverse reactions (Booth 2008).
Literature Cited
1. Grant TR. Ornithorhynchidae. In: Walton DW, RichardsonBJ, eds. Fauna of Australia, Volume 1B, Mammalia. Canberra, Australia: Australian Government Publishing Service; 1989: 436–450.
2. Booth R. Platypus. In: Vogelnest L, WoodsR, eds. Medicine of Australian Mammals.Melbourne, Australia: CSIRO Publishing; 2008: 103–132.
3. Whittington RJ. The role of infectious disease in the population biology of monotremes. In: AugeeML, ed. Platypus and Echidnas. Sydney, Australia: The Royal Zoological Society of NSW; 1992: 285–292.