作為古老的犬種，巴哥犬如今的扁平臉特徵，是二十世紀之後犬業人工選擇的結果[9]。為了符合民眾對於寬大、扁平臉特徵的偏好（這樣的偏好則來自人類對於「似幼童的」特徵的喜愛[10]），犬業縮短了巴哥犬的頭顱並拓寬其口腔頂，以強化扁平臉的特徵。相比十八世紀英國著名繪家威廉·賀加斯在其作品《威廉·賀加斯自畫像》（Painter and his Pug）所描繪的巴哥犬形象中，仍有明顯的吻部；如今美國犬業俱樂部所認可的巴哥犬種吻部標準則是：短、鈍、成方形[11]。中國更有犬業培育出「鷹版巴哥」，增加巴哥犬鼻子上的皺褶，加劇呼吸困難的健康問題。
^Shipley, Joseph Twadell (1955). Dictionary of Early English. New York, EE.UU.: Philosophical Library. pp. 768 pages.
^PLOS. Why flat-faced dogs remain popular despite health problems. Science Daily. 2020-08-26 [2021-01-25]. （原始内容存档于2022-08-11） （英语）. But these breeds are strongly predisposed to a range of severe disorders, including respiratory disease, eye disease, spinal disease, heat stroke and pneumonia, and their lifespan is reduced by on average four years compared to dogs with longer muzzles.
^Esther Woolfson. Love you to death: how we hurt the animals we cherish. The Guardian. 2020-08-11 [2021-01-25]. （原始内容存档于2021-03-15） （英语）. One suggestion is that the “childlike” appearance of dogs such as pugs and bulldogs attracts us
^American Kennel Club. Pug. American Kennel Club. [2021-01-25]. （原始内容存档于2021-03-13） （英语）. The muzzle is short, blunt, square, but not upfaced.
