Pet owners are suing Nutro, a subsidiary of Mars Inc., for allegedly inducing them to buy its dog food products with false statements about their promotion of growth of beneficial bacteria.

The putative class action suit, Monteleone v. The Nutro Co., in federal court in Newark, claims violations of the New Jersey Consumer Fraud Act and includes counts for equitable fraud and negligent misrepresentation.

It was brought on behalf of buyers of Nutro products from all states other than California, from December 2007 to April 2011, a period during which sales of Nutro dog food exceeded $10 million.

Mars, of McLean, Va., a conglomerate best known for M&M’s candies, is also named as a defendant in the suit.

According to the suit, Nutro’s product labels—until corrected in late 2011—listed Bacillus licheniformis and Bacillus subtilis as ingredients, which the company claims formed healthy spores in a dog’s digestive tract. The company discovered its dog food does not form those spores once ingested, prompting it to reformulate its products, but the volume of spores produced by the revised product did not meet the volume claimed on product labels, the suit says.

The allegedly misleading labels included a “guaranteed analysis” with references to “millions of bacillus.” When the defendants made those statements, they “had no reasonable grounds for believing them to be true,” the suit says.

“The failure of an advertiser to substantiate through documents, records or any other written proof any claim regarding the safety, performance, efficiency, quality or price of advertised merchandise shall constitute a per se violation of the New Jersey Consumer Fraud Act,” the complaint says.

The plaintiffs seek actual damages in the amount paid for the products, including sales tax, plus exemplary and punitive damages and attorney fees and costs.

Filed in Essex County Superior Court, on Dec. 26, the case was removed to federal court on diversity grounds on Feb. 10 because class representative Damian Monteleone lives in New Jersey.

The plaintiffs are represented by Ronald Giller and Jeffrey Spiegel of Gordon & Rees in Florham Park and John Donboli of Del Mar Law Group in Del Mar, Calif.

Donboli brought a similar suit on behalf of California consumers in state court in San Diego in 2011. That case, Clark v. The Nutro Co., settled with an injunction against misrepresentations on the product’s label and cash payments of up to $10 or Nutro coupons worth as much as $20 for class members.

The New Jersey case makes the same claims as the California litigation. Donboli says independent testing showed levels of beneficial spores in Nutro dog food are less than what was represented on the label. Though the labels eventually were corrected, “there was a long period when they were duping the public,” he says.

Mars and Nutro are represented by Stephen DeFeo of Brown & Connery in Westmont and David Forkner and Brian Rabbitt of Williams & Connolly in Washington. The defense lawyers did not return calls.

On Tuesday, DeFeo asked for the deadline for Nutro and Mars to file their answer to be extended two weeks, until Feb. 28. The defendants were served on Jan.9, he said.

A Nutro spokeswoman, Monica Glass, declined comment on the suit. •