Possible Clues:

• Ready to drop, like a boxer?
• Setter perhaps tried to change, and became worn out
• Done in colour after wretched fellow rejected it
• Whacked as boxer might be?
• All in shadow tried to move
• Spent dreaming of rabbits?
• Got dried out, though very weary
• Worn out
• Spent one's energy going walkies?
• After rough handling, Roget did get worn out