$ perl -MData::Dumper   -lanF\\\| -e  'for (@F){@x=split /=/;$h{$x[0]}=$x[1]};$pet_hate{$h{pet}}{HATE}{$h{hate}}++;$pet_hate{$h{pet}}{LIKE}{$h{like}}++; }{print Dumper \%pet_hate' your-file.txt 
$VAR1 = {
          '"cow"' => {
                       'HATE' => {
                                   '"rat"' => 3
                                 },
                       'LIKE' => {
                                   '"dog"' => 3
                                 }
                     },
          '"cat"' => {
                       'LIKE' => {
                                   '"horse"' => 1,
                                   '"dog"' => 2
                                 },
                       'HATE' => {
                                   '"rat"' => 3
                                 }
                     }
        };