For the study, Rusbridge and her team took brain, skull and vertebrae measurements of 155 Griffon Bruxellois dogs affected by the condition, and compared the data with measurements taken of normal Griffons.
The researchers discovered that Griffons with the disease had taller foreheads. The condition had also caused the shape of the brain to change, with severely affected animals having their cerebellum (the part of the brain at the back of the skull) pushed underneath the main part of the brain.
Photos: Ugliest Dog Contenders
A dog with the condition might look cute and doll-like on the exterior but, on the inside, its brain could display this terrible malformation.
The problem may happen all on its own, without breeder involvement. The condition can affect humans, for example, but only when certain skull bones fuse too early, causing parts of the brain to push through an opening in the base of the skull. The disease currently affects 1 in 1,280 humans.
In dogs, some breeders can make the disease more prevalent in their quest to churn out attractive canines with little regard to their long-term health prospects.