my @var = (
  [qw(Hund Katze Maus)],
  [qw(Hund Katze Ratte)],
  [qw(Hund Tiger Ratte)],
  [qw(Hund Tiger Maus)],
);

my $hashref = {};
for my $arr ( @var )
{
  my $tmp = \$hashref;
  $tmp = \$$tmp->{$_} for(@$arr);
  $$tmp={};
}

print Dumper($hashref);