More Colorado pet owners reported Thursday that their animals have died from symptoms that might be linked to recalled pet food products, a spokesman for the Food and Drug Administration in Denver said.

The FDA also is looking into a small number of reports that pets have died after consuming food that was not included among the recalled products, said Devin Koontz, the administration's spokesman.

"We're trying to figure it out," Koontz said.

He emphasized that the number of reports concerning dry food consumed by pets that became sick was not alarming.

FDA officials were compiling reports of pets that have died or become sick, and were unable to update the number of deaths Thursday afternoon, Koontz said. As of Wednesday, pet owners in the state had told federal health authorities that 25 animals had died.

Menu Foods Inc., the pet-food manufacturer in Ontario, Canada, notified U.S. authorities last week that it was recalling all of its "cuts and gravy" style cat and dog food that was produced at its facility in Emporia, Kan., according to the FDA. The food is packaged in cans and pouches under several brand names.

The recall was carried out after pet owners complained to Menu Foods that dogs and cats in the U.S. had developed kidney failure after eating the company's food.

The recall covers a period from Dec. 3 to March 6 when the canned and pouched food was sold.

So far, the Canadian firm has reported that 14 animals have died, according to the FDA. Nine cats died during taste trials conducted by Menu Foods.

Pet owners then reported that four cats and one dog had died, federal authorities said.

Although Menu Foods had conducted tests of the pet foods that have been recalled, company officials have been unable to determine what is causing the illnesses.

The company is looking at the possibility that a new ingredient provided by a new supplier might be the culprit. The ingredient was introduced to the food about the same time that consumers started complaining about their pets becoming very sick, Menu Foods said.

The firm has stopped using the ingredient, which was not identified.