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 = $hashref;
  for(@$arr)
  {
    $tmp->{$_} = {} unless( exists $tmp->{$_} );
    $tmp = $tmp->{$_}
  }
}

print Dumper $hashref;