Rolf, I think the OP means something like this:

#!/usr/bin/perl -w

use strict;

use Data::Dumper;

use debug;

{
    my %tstinf = ();

    $tstinf{'Animal'}{'Mammal'}{'Domesticated'}{'Dogs'}{'Poodle'} = 1;
    $tstinf{'Animal'}{'Mammal'}{'Domesticated'}{'Dogs'}{'Greyhound'} =
+ 1;
    $tstinf{'Animal'}{'Mammal'}{'Domesticated'}{'Weasels'} = 1;
    $tstinf{'Animal'}{'Mammal'}{'Undomesticated'}{'Cats'}{'Siamese'} =
+ 1;
    $tstinf{'Animal'}{'Mammal'}{'Undomesticated'}{'Cats'}{'Calico'} = 
+1;
    $tstinf{'Animal'}{'Reptile'}{'Land'}{'Lizard'}{'Gekko'} = 1;
    $tstinf{'Animal'}{'Reptile'}{'Land'}{'Lizard'}{'Salamander'} = 1;
    $tstinf{'Animal'}{'Reptile'}{'Land'}{'Tortoise'}{'Spengleri'} = 1;
    $tstinf{'Animal'}{'Reptile'}{'Water'}{'Mocassin'}{'Blackhead'} = 1
+;
    $tstinf{'Animal'}{'Avian'}{'Bird'}{'Predator'}{'Raptor'} = 1;
    $tstinf{'Vegetable'}{'Ground Plant'}{'Edible'}{'Leafy'}{'Lettuce'}
+ = 1;

    my @unikey = &getUniqueKeys('', \%tstinf);

        print Dumper \@unikey;
}
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