Studies of dog DNA have revealed a genetic mutation linked to flat face shapes which could help pave the way to diagnose an abnormal skull condition.
Researchers at the University of Edinburgh's Roslin Institute analysed DNA samples from 374 pet dogs of various pedigree and mixed breeds.
The animals underwent CAT scans as part of the project, producing detailed 3D images of their heads.
These allowed the scientists to take precise measurements of the shape of the dog's skull and then pinpoint DNA variations associated with different head shapes.
Dr Jeffrey Schoenebeck, of the institute, said: "Our results shed light on the molecular nature of this type of skull form that is so common and popular among dogs."
One variation, found to disrupt the activity of a gene called SMOC2, was strongly linked to the length of the dog's face.
Animals with the mutation, such as pugs and bulldogs, had significantly flatter faces.
The condition is known as brachycephaly and can be found in human babies too, though little is known about its causes.
Scientists now say screening children for changes in the SMOC2 gene could help to diagnose the condition.