my $regex = "the (animals|dogs|cats).+?are ready to eat.";
my $compiled_regex = qr/$regex/;

# store $compiled_regex in a database

# later on, retrieve the $compiled_regex_from_db

my $compiled_regex_from_db = [DBI query and unserialize or thaw?];

my $teststring = "the dogs who are friendly are ready to eat.";
$teststring =~ s/$compiled_regex_from_db/creatures/;