A Basset hound.
Photograph by Joël Sartore, National Geographic Photo Ark
A Labrador mix.
Photograph by Joël Sartore, National Geographic Photo Ark
This dog is part Basset hound and part blue heeler.
Photograph by Joël Sartore, National Geographic Photo Ark
An Akita/pit bull mix.
Photograph by Joël Sartore, National Geographic Photo Ark
A Welsh corgi.
Photograph by Joël Sartore, National Geographic Photo Ark
A chocolate Labrador retriever.
Photograph by Joël Sartore, National Geographic Photo Ark
A two-month-old pit bull mix.
Photograph by Joël Sartore, National Geographic Photo Ark
An Airedale terrier.
Photograph by Joël Sartore, National Geographic Photo Ark
A three-month-old Chihuahua.
Photograph by Joël Sartore, National Geographic Photo Ark
A yellow Labrador retriever.
Photograph by Joël Sartore, National Geographic Photo Ark