The results of pure-breeding, on display starting this Saturday at the Westminster Kennel Club Dog Show in New York, are profound. Erich Andres/United Archives, via Getty Images Modern shepherds have more pronounced slopes A German shepherd at the 2013 Westminster Kennel Club Dog Show. Imagno/Getty Images Modern pugs have smushed, round faces A pug at the 2013 Westminster Kennel Club Dog Show. Fox Photos/Getty Images Modern chows are slightly larger, with more fluffy fur A chow at the 2013 Westminster Kennel Club Dog Show. Fox Photos/Getty Images Modern bull terriers have more football-shaped heads A bull terrier at the 2013 Westminster Kennel Club Dog Show.

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Persons: Davis, Erich Andres, Fred R, Conrad, Danika Bannasch, Cane Corso, Pugs, Imagno, Chow chows, chow, Bull Organizations: American Kennel Club, University of California, Wisdom Health, Westminster Kennel, Danes, United, Getty, The New York Times, Fox, American Kennel Locations: Finland, New York, Rhodesian