Australian pedigree dog lovers are choosing dogs with severe genetic risks over healthier breeds, analysis shows.

Pugs and bulldogs are gaining ground over Labradors and German Shepherds in pedigree dog-collecting circles, a study from the University of Sydney shows.

Australian fans of purebred dogs now favour small, brachycephalic breeds – with shorter and wider heads – which are more susceptible to respiratory problems, skin and eye conditions, and digestive disorders.

Data on each breed registered is published each year by the Australian National Kennel Council (ANKC), and suggest veterinarians may need to prepare to treat more dogs with these conditions.

The study, published in Canine Genetics and Epidemiology, investigated changes in the AKNC’s registration statistics between 1986 and 2013, examining trends in demand for Australian purebred dogs of various height, size and head shape.

The preference for smaller dogs correlates with a trend towards more high density living, says one of the lead researchers Professor Paul McGreevy.

“Changes in the types of dwellings Australians are buying may indicate the space available for dogs has shrunk,” McGreevy says.

“Moreover, the purpose of dog ownership has continued to shift from the early days of domestication, away from duties such as hunting and guarding properties, for which dogs are more likely to be larger, to pure companionship, which can be fulfilled by a dog of any size.”

Reasons behind the penchant for dogs with short, wide faces are less obvious, but could reflect fashion or other aesthetic trends.

“Other studies also indicate the infantile facial features commonly seen in brachycephalic dogs with their round faces, chubby cheeks, big eyes and small nose and mouth, stimulate feelings of affection in humans,” McGreevy said.

Unfortunately, life expectancy among these popular breeds is an estimated four years lower than non-brachycephalic breeds. Brachycephalic Airway Obstruction Syndrome (BAOS) is particularly prevalent, often resulting in mild to life-threatening respiratory problems.

“A study in the UK shows half of owners of breeds susceptible to these health issues seem unaware of BAOS in their dogs,” the expert said.

“This implies owners did not make a fully informed decision when purchasing their brachycephalic dog, and that they may be unaware of treatment options when BAOS emerges, and that affected dogs may breed and pass the predisposition to BAOS onto future generations.”

Professor McGreevy and fellow researcher Kendy Teng’s study used AKNC data covering about 16.5 percent of newborn puppies in 2014, and therefore may not be representative of the general dog population in Australia.

The researchers stress that the figures most likely reflect trends in Australia’s purebred population.