by

Sonia Vasquez 

A preliminary treatment trial for sarcoptic mange in wombats is underway, in the hope that the spread of this devastating condition can be controlled. Dr Matt Hartley, who is conducting the research as part of a Masters in Wildlife Health and Population Management at the University of Sydney, has been monitoring wombat populations at Canyonleigh, New South Wales, for the past six months.

Please click on thumbnails to enlarge

Female Common wombat, grazing: this female did not require sedation for evaluation. Her mange is so severe that she was found grazing in the middle of a dirt road, seeking the additional protein she requires due to the mange burden.

"Infection with the sarcoptic mange mite causes the animal to develop thick, crusty lesions, severe alopecia and pruritis," said Dr Hartley. "In advanced stages the crust cracks, allowing secondary infections and septicaemia. The increasing protein requirement of the animal means that it must feed for many more hours in the day, and increase its home range dramatically in order to find sufficient nutrients. Even so, I have observed dramatic weight-loss in infected animals, and severely infected wombats can weigh half of the normal body weight of a healthy animal."

"The lesions infect the eyelids and cause severe conjunctivitis and crusting of the ears. The normally acute senses of the wombat are severely inhibited. Reproductive activity ceases completely, and all infected animals will eventually die, some as rapidly as two to three months after initial infection. The disease causes terrible suffering and can cause local extinction of wombat populations."

Although wombats have been successfully treated in captivity, due to the requirement for repeated medication, the treatment of wild wombats has proven impossible, as the mite can survive in wombat burrows for longer than the effective life of the drugs. It has therefore been necessary for National Parks and Wildlife rangers to euthanase severely infected animals to prevent prolonged suffering.

Sarcoptic mange is the biggest threat to wombats after human impact, particularly road kills and persecution by land-owners. The disease could cause extinction of the remaining 80 Northern Hairy-Nosed Wombats that survive in Epping Forest National Park in Northern Queensland, if introduced to the area. With the decline of all three species of wombat throughout Australia, a successful treatment for mange would be a major breakthrough for wombat conservation.

Female Common wombat, heavily sedated for treatment. Severe mange is evidenced by thick crust on skin and heavy alopecia.

Dr Hartley's clinical trial involves a dual treatment with canine products; selamectin (Revolution, Pfizer) and Fipronil spray (Frontline, Merial). A higher dose is required as wombat skin is over one centimetre thick. Dr Hartley then radio-tracks animals in the trial to monitor the success of the treatment. Ultimately, if the treatment proves effective, National Parks and Wildlife rangers will be able to administer a once-only treatment and re-release the animals immediately.    Wombat conservationists are not only concerned about sarcoptic mange: other infectious diseases could also have an impact on wombat populations.

Dr Hartley has undertaken the first serological study of toxoplasmosis in wild wombats, and has found that while 20 per cent of animals in the study have been exposed to toxoplasma gondii, none show evidence of clinical infection. "This suggests that toxoplasmosis carried by feral cats does not have the same impact on wild populations as it does on captive populations," he said.    Dr Hartley has also found a low percentage of wombats infected with Leptospirosis. "Leptospirosis is becoming increasingly important in Australia's cattle and sheep industries. Work carried out 20 years ago suggested that wombats may be involved in the transmission of this disease, but my findings suggest that this is not the case."

This work on infectious diseases is another piece of the wombat conservation puzzle that various groups are working to complete in time to save Australia's three wombat species.

The clinical trial is being sponsored by Virbac Australia, Pfizer Animal Health and Novartis Animal Health. Dr Hartley can be contacted on mhzoovet@yahoo.com

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This article is reprinted from the February Issue of “The Veterinarian” and is done so with their kind permission and that of the author.

For more visit www.theveterinarian.com.au