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Dog sniffs out sheep poo parasites |
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Scientists have trained a German Shepherd to sniff out parasite infected sheep poo, paving the way for an electronic 'nose' that could save the sheep industry millions.
Dr Mark Sandeman from La Trobe University and James Rowe, Director of the Australian Sheep Industry Cooperative Research Centre (CRC), were considering the possibility of detecting sheet parasites with an electric nose, but decided that using a dog might quickly show whether parasites had smells.
"Scents, and the use of sniffer dogs to detect them, are used to determine the presence of substances including bladder cancer in humans, accelerants at fire scenes, weeds, drugs, explosives, moth eggs and termites," Mark said.
"Dogs have the most sensitive noses - better than electronic biosensors - so we set out to ascertain whether the presence of intestinal parasites in sheep could be detected by their scent."
As nasty as they sound, gastrointestinal nematodes (a type of roundworm) are responsible for serious production losses for Aussie sheep farmers. They can interfere with a sheep's wool and meat growth, and make the animal weak and susceptible to other diseases. What's worse, many of the parasites have become resistant to drug treatment.
Last year, Mark and research student Kate Richards got hold of two female German Shepherd puppies, Elle and the scientific-sounding Seb (Scent Experiment B).
With a professional dog trainer on board and funding from the Australian Sheep Industry CRC, they set out to determine whether gastrointestinal nematodes had an odour and whether different species had individual odours. And if the answers were yes, they needed to find out if a dog could to detect these scents.
In what must be some of the smelliest science around, they placed bags of poo from infected sheep among bags of poo from healthy sheep. After six months of patient, painstaking training, the dependable Seb was able to detect the infected faeces by its odour. More flighty, Elle failed and was 'voted off' the project.
After more training, super-sniffer Seb could detect the presence of infections in sheep poo with 80 to 90 per cent accuracy.
"Initially we thought we could translate the dog to a farm situation, but that would require ongoing training. Alternatively the dog could work with a contractor, but costs would increase," explained Mark.
So the scientists decided to develop an electronic hand held 'nose'.
"Once Seb had shown us that the parasites had odours and could be detected by smell, the next step was to isolate the odour molecules of the different parasites," he said.
So the research moved into the lab, where PhD student, Jacquie Burgess worked with a mass spectrometer to detect the specific molecules associated with the parasites.
"The work is proceeding well. We have isolated odour molecules associated with Telodorsagia, the small brown stomach worm common in sheep in Australia. The worm is closely related to a worm common in cattle, potentially extending the system."
If the team can find the odour compounds peculiar to major parasite infections, they could design an electronic 'nose' to detect them.
"Once we're sure of the smell of more parasites, we'll talk to biosensor manufacturers. We hope to use existing technology to make a hand-held device which farmers can hold near poo to check individual animals," said Mark.
The ultimate aim would be to test every sheep to determine which to drench. Not drenching all animals would save money and decrease parasite drug resistance. Animals repeatedly infected could be culled out of breeding programs, leading to stronger flocks.
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