Overweight dachsund undergoes incredible weight loss

Dennis the Dachshund used to weigh 56 pounds. (AP)

The dog was being fed White Castle burgers and pizza before being rescued. (Dennis' Odyssey / Brooklyn Burke / Facebook)

Now Dennis only weighs 12 pounds after starting to eat dry dog food and going on lots of walks. (Dennis' Odyssey / Brooklyn Burke / Facebook)

Dennis' owner, Brooke Burton, said the dog has undergone skin removal surgery. (Dennis' Odyssey / Brooklyn Burke / Facebook)

But Dennis is much more active now, playing fetch and interacting with other dogs. (Dennis' Odyssey / Brooklyn Burke / Facebook)

(Dennis' Odyssey / Brooklyn Burke / Facebook)