The process of selectively breeding dogs has developed over the last 1,000 years as a way to “engineer” dogs for different types of work and play. But where it once may have served a purpose, it became more about aesthetics over time.

As a result, many dog breeds are nearly unrecognizable from a century ago. Worse still, many of the changes bred into these dogs have caused major health complications.

Have a look at some historical breed images placed side-by-side with the modern versions of the these breeds. The comparison will surprise you.

1. St. Bernard.

01-dog-breeding-gone-wrong

2. Bull Terrier.

02-dog-breeding-gone-wrong

3. German Shepherd.

03-selective-dog-breeding-gone-wrong

4. Bassett Hound.

04-dog-breeding-gone-wrong

5. Pugs.

05-dog-breeding-gone-wrong

6. Boxers.

06-dog-breeding-gone-wrong

7. English Bulldogs.

07-selective-dog-breeding-gone-wrong

8. Corgi.

13-selective-dog-breeding-history

9. Dachshund.

doxie

10. White Terrier.

white-terrier

11. Old English Sheepdog.

11-selective-dog-breeding-history

12. Chow Chow.

12-selective-dog-breeding-history

13. French Bulldog.

08-dog-breeding-history

14. Poodles.

14-selective-dog-breeding-history

15. Chihuahua.

20-selective-dog-breeding-history

16. Pomeranian.

16-selective-dog-breeding-history

17. Chinese Shar Pei.

17-selective-dog-breeding-history-improvements

18. Neapolitan Mastiff.

18-selective-dog-breeding-improvements

19. Pit Bull.

19-selective-dog-breeding-history-improvements

20. Boston Terrier.

15-selective-dog-breeding-history

21. Doberman.

doberman

22. Saluki.

saluki

23. Bearded Collie.

bearded