According to IRI sales-tracking data, petfood sales through mass-market outlets (Packaged Facts defines these outlets as supermarkets, drugstores and mass merchandisers excluding Walmart) totaled US$6.5 billion in retail for the 52 weeks ending January 27, 2013, up 0.3% from January 2012. Mass-market outlets lead in petfood sales, with supercenters/mass merchandisers…