Tests turned up rat poison in the pet food suspected of causing kidney failure in dogs and cats across the country and killing at least 16, state officials and scientists announced Friday.
The toxin was identified as aminopterin, which is used to kill rats in some countries, state Agriculture Commissioner Patrick Hooker said. Aminopterin is not registered for killing rodents in the United States, though it is used as a cancer drug, according to the Environmental Protection Agency.
State officials did not say how they believe Aminopterin got into the now-recalled pet food, though they said no criminal investigations had been launched.
The Food and Drug Administration has said the investigation was focusing on wheat gluten in the pet food. Wheat gluten itself would not cause kidney failure, but the common ingredient could have been contaminated, the FDA said.
The pet deaths led to a recall of 60 million cans and pouches of pet food produced by Menu Foods and sold throughout North America under 95 brand names. There have been several reports of kidney failure in pets that ate the recalled brands, and the company has confirmed the deaths of 15 cats and one dog.
Menu Foods last week recalled "cuts and gravy" style dog and cat food. The recall sparked concern among pet owners across North America. It includes food sold under store brands carried by Wal-Mart, Kroger, Safeway and other large retailers, as well as private labels such as Iams, Nutro and Eukanuba.
Menu Foods is majority owned by Menu Foods Income Fund of Streetsville. The company also makes foods for zoo cats, but those products are unaffected by the recall.
The company's chief executive and president said Menu Foods delayed announcing the recall until it could confirm that the animals had eaten its product before dying. Two earlier complaints from consumers whose cats had died involved animals that lived outside or had access to a garage, which left open the possibility they had been poisoned by something other than contaminated food, he said.
Menu Foods planned a media teleconference for later Friday, a spokesman said.
A spokesman for New York Attorney General Andrew Cuomo said he was not aware of any criminal investigation involving the tainted food. FBI spokesman Paul Holstein in Albany said Friday he was not aware of any FBI involvement in the case.
"I don't know where we'll go from here," he said.
Aminopterin, also used as a cancer drug, is highly toxic in high doses. It inhibits the growth of malignant cells and suppresses the immune system.
A complete list of the recalled products along with product codes, descriptions and production dates was posted online by Menu Foods and is available at http://tinyurl.com/2pn6mm. The company also designated two phone numbers that pet owners could call for information: (866) 463-6738 and (866) 895-2708.