ST. LOUIS – Nestle Purina PetCare Co. is suing The Blue Buffalo Co. Ltd., over Blue Buffalo’s pet food ingredient claims. In turn, Blue Buffalo says Purina just can't take the heat of competition.

The lawsuit, which was filed in federal court in St. Louis, alleges Blue Buffalo engaged in false advertising, disparagement and unjust enrichment. Purina alleges that testing by an independent laboratory found several of Blue Buffalo's "Life Protection" brand of pet foods contained "significant percentages of poultry by-product meal", contrary to the company's advertising which asserts Blue Buffalo pet products don't contain chicken or poultry by-product meals.

"This is not an action we take lightly," said Steven Crimmins, vice president and CMO of Nestle Purina. "We believe consumers deserve honesty when it comes to the ingredients in the food they choose to feed their pets.

"Our commitment to owners and their pets is not a marketing ploy or advertising slogan," Crimmins added. "At Purina, what goes in the bag goes on the label."

But in a letterto customers Bill Bishop, founder and chairman of Blue Buffalo, denied Purina's allegations, saying the company looks forward to disproving Purina's "voodoo science".

"We're disappointed to see one of the largest food companies in the world with over $100 billion in sales launching such a baseless lawsuit against a family-run company and attempting to prosecute it on the internet," Bishop said. "In some ways this attack by Nestle Purina is not too surprising, since pet parents have demonstrated their preference by selecting true natural foods like Blue Buffalo instead of the by-product and corn-based pet foods Nestle Purina has been selling for years. In fact, their inability to compete successfully with natural pet foods is the key motivation for this frivolous lawsuit."

Purina has created a websitehighlighting its concerns about Blue Buffalo's advertising practices.