## Instead of ## my %lookup_id = map { $_->{id}, $_ } @rows;
my %lookup_fur_and_legs;
push (@{ $lookup_fur_and_legs { $_->{fur} . $_->{legs} } }, $_ ) for  @rows;

# This now allows, given any fur-legs combo : $fl,
for my $row (@{ $lookup_fur_and_legs{$fl} } ){
   # WHatever you want with each row for thes $fl ...
}