Underwood, 31, donated the autographed guitar to help pay the medical bills of Kevin Branscum's German shepherd named Gino. Underwood is a native of the Oklahoma city of Checotah, reported Fox online.
Gino has already cost his master around USD 4,000 since December (14) after being infected with heartworms but the animal needs further treatment in May.
Officials plan to auction the guitar but haven't set a venue or date.
Branscum said he was surprised by Underwood's donation and is incredibly grateful.