1) it's while not While
2) the replacing works wrong

#!/usr/bin/perl -w

while(<DATA>){
    $_=~s/^(BEGTITLE.*) (wirey) (.*ENDTITLE)$/\1 smooth \3/i;
    print $_;
}
__DATA__
BEGPUB Wirey Haired Dogs Life ENDPUB
BEGTITLE My dog has wirey hair ENDTITLE
BEGTXT My wirey hair dog...blah, blah. ENDTXT
[download]

and don't cut the extra spaces

--
package Lizard::King;
sub can { do { 'anything'} };
[download]