Washington ? Federal testing of recalled pet foods turned up a chemical used to make plastics but failed to confirm the presence of a cancer drug also used as rat poison. The recall expanded Friday to include the first dry pet food.

The Food and Drug Administration said Friday it found melamine in samples of the Menu Foods pet food involved in the original recall and in imported wheat gluten used as an ingredient in the company’s wet-style products. Cornell University scientists also found melamine in the urine of sick cats, as well as in the kidney of one cat that died after eating some of the recalled food.

Meanwhile, Hill’s Pet Nutrition recalled its Prescription Diet m/d Feline dry cat food. The food included wheat gluten from the same supplier that Menu Foods used. The recall didn’t involve any other Prescription Diet or Science Diet products, said the company, a division of Colgate-Palmolive Co.

The FDA was working to rule out the possibility that the contaminated wheat gluten could have made it into any human food. However, melamine is toxic only in high doses, experts said, leaving its role in the pet deaths unclear.

Menu Foods recalled 60 million containers of cat and dog food, sold throughout North America under nearly 100 brands, earlier this month after animals died of kidney failure after eating the Canadian company’s products. It is not clear how many pets may have been poisoned by the food, although anecdotal reports suggest hundreds if not thousands have died. The FDA alone has received more than 8,000 complaints; the company, more than 300,000.

Company officials on Friday would not provide updated numbers of pets sickened or killed by its contaminated product. Pet owners would be compensated for veterinary bills and the deaths of any dogs and cats linked to his company’s products, the company said.