#!/usr/bin/perl -w
    use strict;
    $/ = undef;
    my $text = <DATA>;
    $text =~ s/(BEGTITLE.*?)wirey(.*?ENDTITLE)/$1smooth$2/gsi;
    print $text;
    __DATA__
    BEGTITLE The wirey life of a wirey haired dog ENDTITLE
    BEGTXT blah blah blah ENDTXT
    BEGTITLE Grooming dogs ENDTITLE
    BEGTXT Grooming a wirey haired dog is ... ENDTXT
    BEGTITLE Last wirey haired dog story ENDTITLE
    BEGTXT we don't need no steenkin' wirey haired dogs here ENDTXT

# output is:

    BEGTITLE The smooth life of a wirey haired dog ENDTITLE
    BEGTXT blah blah blah ENDTXT
    BEGTITLE Grooming dogs ENDTITLE
    BEGTXT Grooming a smooth haired dog is ... ENDTXT
    BEGTITLE Last wirey haired dog story ENDTITLE
    BEGTXT we don't need no steenkin' wirey haired dogs here ENDTXT