Scientists have uncovered a stem cell in dogs which could lead to new treatments for bone cancer in children, according to an Edinburgh study.
The cancer stem cell makes copies of the disease, enabling it to spread around the body. It appears notoriously resistant to treatment.
But by identifying it, it may be possible to work out how to target it.
Osteosarcoma in dogs is molecularly similar to bone cancer in children, The Veterinary Journal study noted.
The idea that faulty stem cells drive the development of some cancers is gaining momentum
Henry Scowcroft of Cancer Research UK
It is the most common form of bone tumour in young people, and more than 80% risk losing a limb as a result.
"The rogue cancer stem cell is key in the whole process," said Professor David Argyle of the Royal Vet School at the University of Edinburgh.
"We identified it by growing cells in particularly harsh conditions but whereas other cancer cells died off, this stem cell was able to survive."
Around 30 children develop osteosarcomas in the UK each year. They occur more commonly in older children and teenagers, usually boys, and are very rarely seen in children under five.
The causes are unknown, but it is thought that children who have an inherited retinoblastoma - a rare tumour of the eye - are at increased risk.
Henry Scowcroft, senior cancer information officer at Cancer Research UK, said: "The idea that faulty stem cells drive the development of some cancers is gaining momentum.
"This discovery lends more weight to this theory, and opens up new avenues of research that could one day lead to new treatments."
But he cautioned: "The finding came from studies of cancer in dogs so it remains to be seen whether it holds true in humans."