Book is old but complete, has both covers but is beat up.  Completely readable.

Written by Whitley Strieber

Bob Duke dreamed of becoming a wolf.  Of running free on four strong legs.  Howling, Stalking, Living with nature, in nature.  Then his dreamcame true - and threatened to become a nightmare.  Bob's wife and son vow to restore his hamity.  But even if they can find him - a man-wolf loose in the concrete forests of Manhattan - will he even want to become human again?  Once set free, no cage can hold back... The Wild.