foreach (@animals) { $animals{$_}++; }  # initialize %animals hash

# could be
$animals{$_}++ for @animals;
[download]

Regarding:

# use a for loop
for (@animals) {
  last if $_ eq 'dog';
}
print "We have a dog!\n";
[download]

That'll always print 'We have a dog!', even when we don't.