roboticus@Boink:~$ cat 854238.pl 
my $text = "Kev.has.a.stupid.perl.question";
$text =~ s/\./\\./g;
$text .= ".";
print $text;

roboticus@Boink:~$ perl 854238.pl
Kev\.has\.a\.stupid\.perl\.question.

roboticus@Boink:~$ perl -d 854238.pl
  ...snip...
main::(854238.pl:1):	my $text = "Kev.has.a.stupid.perl.question";
  DB<1> b 3
  DB<2> r
main::(854238.pl:3):	$text .= ".";
  DB<2> p $text
Kev\.has\.a\.stupid\.perl\.question
  DB<3>