As many as one in six animals died in tests of Ontario-based Menu brand pet foods suspected of poisoning pets in the United States, a U.S. government official has said.

Menu Foods has now issued a North America-wide recall of 91 different kinds of dog and cat food, after the U.S. Food and Drug Administration received complaints the food was causing kidney failure in animals.

The investigation is focusing on wheat gluten used at two U.S. plants as the likely source of contamination.

The FDA first learned of a potential problem after receiving complaints on Feb. 20 and followed up by feeding the "cuts and gravy" product to 40 to 50 cats. Of those, seven animals died, said Stephen Sundlof, the FDA's top veterinarian. He added the contamination appeared more deadly to cats than to dogs.

Menu Foods, which is based west of Toronto in Streetsville, Ont., has so far reported 10 deaths — nine cats and one dog.

Cases of poisonings may also be appearing in Canada.

Torontonian Jovana Kovacevic told the CBC Monday her seven-month-old cat, Djole, became lethargic and stopped eating two weeks ago. The cat later died of kidney failure and a second cat, four-month-old Tosa, is on intravenous medication after having eaten the food.

Cynthia Lawrie of Drumheller, Alta., also blames the recalled food for the death of one of her cats.

Lawrie has two other cats that also ate the food. One is still at the veterinarian's, she said. Another has come home, but is being monitored.

The Menu Foods recall covers pet foods sold throughout North America under the Iams,Nutro and Eukanuba labels. In Canada, the recall also coversLoblaw's President's Choice brand, as well as the house brands for Dominion, Sobeys andother supermarket chains.

Company tells customers to hold onto vet bills

A company spokesmansaidcustomers shouldhold on to packaging and vet billsin case financial compensation is offeredin the future.

Veterinarian Scott Bainbridge of the Queen West Animal Hospital advises pet owners who may have fed the affected products to their animals to watch their pet for symptoms of kidney problems.

If they have become lethargic, started vomiting or can't seem to hold their water, it may be wise to call the vet.

"I think if you are feeding one of the foods that are on that [recall] list, I think you need to figure out whether you're in the recall area, and until you know that, I think you need to stop feeding that food right now," he said.

With files from the Associated Press