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584 Australian Veterinary Journal Volume 82, No 10, October 2004

Veterinarians are racing against timeto save Tasmania’s national icon.Investigating the deadly Devil

Facial Tumour Disease (DFT), Dr StephenPyecroft and his team at Mount PleasantAnimal Health Laboratories, Hobart areworking feverishly to stem an estimated50% devastation of the island’s Tasmaniandevil population. In some areas up to 90%of the population have been wiped out.

To date only juvenile devils appear to beimmune to the mystery cancer that beginsas small lumps and lesions around themouth before spreading aggressively intolarge tumours around the face and neck,killing adult animals within six months.

Supervisor of the DFT Project, Dr Stephen Pyecroft said no previous casesof DFT have been reported in worldwildlife and he and his team are dealingwith a new disease.

“It appears epidemiologically that thedisease seems to be acting like an infectiousagent and for tumours that’s weird, “ DrPyecroft said.

“So we’ve either got some sort of agentie: viral or the thing is specificallytransmissible and that’s something we haveto determine.”

“We can have five sets of eyes over themicroscope at any one time and we’ll getfive different opinions so it’s a realchallenge. At first everyone thought it wasa standard lymphoma but basically it’s around cell tumour and we’re tending tolean towards more non differentiated celltypes.”

To help find the answers the researchteam of four pathologists and fourtechnical officers have launched a multi-layered approach to the research.

Using cytogenetics to grow tumourcells and normal cells from affected andhealthy Tasmanian devils, the teamappears to have established a geneticidentity to the tumour which they hopewill help define what they are dealing with.

However, growing cell cultures andconducting immunohistochemistry for thedevils is not easy especially when theprimary antibodies are designed to workwith human and dog tissues but not inTasmanian devils.

Consequently the research team is nowadapting procedures developed for thekoala retrovirus.

“We’re looking at using someimmunohistochemistry stains from aKoala research group at UQ that have gotthem to work in other marsupials and seeif we can get them to take with a truepositive or true negative with the devils.”

Aside from identifying the causativeagent, Dr Pyecroft said his team was alsoexamining the possibility of reservoirpopulations and if the disease is specificallytransmissible. They are also working torule out the zoonotic potential of DFT.

“We haven’t seen the cell types we’veseen in the tumour in any other animalsbut who knows we may have reservoirhosts and animals that carry the diseasethat don’t show it.”

Pyecroft believes if DFT istransmissible from devil to devil that it willmake the management plans a lot easier.

Tasmania has plenty of peninsulas allover the state where teams of field workerscould potentially isolate unaffectedpopulations to help maintain the species.He also cites plans to develop autogenousvaccines where you could actually jab anunaffected population with attenuatedcells.

To help rule out a lot of viral work the

Mount Pleasant team are also utilisingmicro satellite technology, PCR andmolecular genetics.

Veterinary pathologist and teammember Dr Richmond Loh has beenconducting weekly autopsies on a range ofTasmanian devils and taking fat and tissuesamples as part of the DFT project.

He has also ventured out in the field totest infected animals and said despitemaking some encouraging progress thesituation was frustrating.

“So far we know it’s not a muscle cancerbut the huge stumbling block is that we’renot able to rule in or out round cellcancer,” Dr Loh said.

“We’ll be building a holding facility forlive specimens so we can get some answerswith clinical progression. We’ve beenputting it off due to animal ethics issuesbut we’ve come to a stage where it’s theonly way we can proceed.”

“Because there’s no real reference rangesavailable for devil bloods the team areforming a databank to try and establishnormal healthy devil reference ranges tohelp identify the differences between thediseased devils.”

“The team are also examining theimmunology of devils and trying toestablish if the populations are predisposedto DFT.”

At stake is the world’s only marsupialthat is a top order predator of anecosystem. For Dr Pyecroft and the fieldstaff of Tasmanian’s Nature ConservationBranch the real challenge is finding cleanpopulations of devils to help set up solidcomparisons with affected animals.

“We have a team now sampling apopulation in the north west that up todate has had no affected animals in it.

“The genetic basis of the north westpopulation seems to be completelydifferent from the devils in the rest of thestate. At the moment they’regeographically and environmentallyisolated and we hope they remain thatway.”

Wildlife officers have developed anextensive survey and monitoring programincluding examining and re-releasingdevils and recording the devils’ movementswith remote sensor cameras.

Devils AdvocatesBy Mark Thornley

Top: DFT begins with small lesions on thedevil’s lip. Bottom: Advanced DFT

manifesting in large tumours on the face andneck. Photos courtesy of Dr Richmond Loh.