sub get_coordinates {
    $self = shift;
    return $self->SUPER::get_coordinates(), get_z();
}
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This is explained in much more detail in the Overridden Methods section of perltoot, which you should read if you want to learn about OO mechanics in Perl.

#!/usr/bin/perl

use Data::Dumper;
use Animal::Dog;

my $rex = Animal::Dog->new();
print Dumper($rex);
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package Animal;

use strict;
use warnings;

sub new {
    my ($class) = @_;
    my $proto = {need_oxygen => 1};
    return bless($proto, $class);
} 

1;
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package Animal::Dog;
use base "Animal";

use strict;
use warnings;

sub new {
    my ($class) = @_;
    my $self = $class->SUPER::new();
    $$self{domesticated} = 1;
    return $self;
} 

1;
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$VAR1 = bless( {
                 'domesticated' => 1,
                 'need_oxygen' => 1
               }, 'Animal::Dog' );
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For instance, in Animal::Dog::Husky->some_method body, you can call some inherited method and you do not care if that method is written in Animal or in Animal::Dog class.

UPDATE: s/inherited/overiden/