Flat-Faced Dogs Live With 'Harmful' Brain Changes, Owners Warned

You might have heard that flat-faced dogs like pugs and bulldogs are born with breathing difficulties because of the shape of their face. But new research has shown that their shortened skulls are also associated with sleep problems and deterioration in the brain.

French bulldogs are the most popular breed in the U.S., according to Forbes Advisor. But, as a result of their short skull structure, these dogs are prone to brachycephalic obstructive airway syndrome, a set of upper airway abnormalities that affect short-nosed dogs. Their shortened skull has also been associated with distortion and rounding of the brain.

Now, researchers from Hungary's Eötvös Loránd University have shown that these factors can negatively affect the dogs' ability to sleep. In a study published in the journal Brain Structure and Function, the team studied the sleep of 92 family dogs using an electroencephalogram (EEG), a test that measures electrical activity in the brain.

"We wanted to investigate whether flat-faced dogs sleep differently from other dogs, as they are known to suffer from oxygen deprivation due to respiratory problems and therefore have poorer quality sleep," study co-author Zsófia Bognár said in a statement.

The participating dogs were each brought to a sleep lab, where they were hooked up to the EEG.

"In the sleep lab, dogs spend about three hours with their owners," Anna Kis, one of the study's co-authors and a researcher at Hungary's Institute of Cognitive Neuroscience and Psychology, said in a statement.

"As nothing exciting happens, the dogs fall asleep quickly. Meanwhile, we conduct the electrical potential generated by the brain activity with electrodes glued to their scalps," Kis said.

Interestingly, the flat-faced dogs spent more time on average sleeping during this three-hour window. "More daytime sleep is probably compensation for insufficient sleep at night," Bognár said. "But when we studied the EEG patterns, we got more exciting results than that."

From the EEG, they were able to analyze different sleep phases and brain wave patterns.

"In the present study, we found that brachycephalic [short-faced] dogs had decreased beta waves and increased delta compared to dogs with longer noses," study first author Ivaylo Iotchev said in a statement. "This pattern has previously been associated with poorer learning in dogs and loss of white matter in humans."

Exactly why they saw these results is still unclear. "There may be several reasons for our results," Enikő Kubinyi, a study co-author and the research group's leader, said in a statement. "The most interesting of these is that it seems as if the flat-faced dogs have retained the sleep pattern of puppyhood, similarly to newborns who spend more time in REM sleep.

Kubinyi said it is widely assumed that brachycephalic dogs are selected for infant-like traits.

"They have large heads and eyes, high foreheads and small noses because we humans find these traits irresistibly attractive," she said. "It is possible that the selection of dogs to be infant-like in appearance has also infantilized their brain function. But this is a bold assumption for now. What is very likely, however, is that breeding for brachycephalic heads leads to potentially harmful changes in brain function."