Alpo is added to recall list of pet food

The recall of wet and dry pet foods contaminated with a chemical found in plastics and pesticides expanded Saturday to include a new brand. But investigators still weren’t sure why the substance would kill dogs and cats.

Nestle Purina PetCare Co. said it was recalling all sizes and varieties of its Alpo Prime Cuts in Gravy wet dog food with specific date codes. Purina said some contained a contaminated wheat gluten from China.

The same supplier also provided wheat gluten, a protein source, to a Canadian company, Menu Foods, which this month recalled 60 million containers of wet dog and cat food manufactured under 100 brand names.

A greater sensitivity of cats could explain why they have died in larger numbers than dogs after eating contaminated pet food, experts said Saturday.