http://abcnews. go.com/US/ story?id= 2975912&page= 1



March 23, 2007 - ABC News has learned that investigators have determined

that a rodent-killing chemical is the toxin in the tainted pet food that has

killed several animals.

A source close to the investigation tells ABC News that the rodenticide,

which the source says is illegal to use in the United States, was on wheat

that was imported from China and used by Menu Foods in nearly 100 brands of

dog and cat food.

Watch "World News" for full details on the extent of the poisoning.

A news conference is scheduled for this afternoon by experts in Albany,

N.Y., where scientists at the state's food laboratory made the discovery a

week after a massive recall of 60 million cans and pouches was issued.

The chemical is called aminopterin.

What investigators can't say so far is whether this is the only contaminant,

if it is in all of the recalled food, or if it's in enough quantity in to

sicken more animals.

There is some good news according to the source. Knowing the chemical should

aid veterinarians who are treating animals that have been sickened by the

pet food.

Aminopterin is used in the United States in, of all things, a cancer drug,

according to the source.

For a week, investigators have been looking for a cause behind the 15

confirmed pet food deaths tied to contaminated pet food. Many animal

doctors, including those at New York's Animal Medical Center, suspect there

will be a much larger rash of cases after they learned about an additional

200 reported cases of kidney failure in animals.

Doctors at the hospital, which is considered the Mayo Clinic of veterinary

medicine, say they noticed the kidney failure while studying sick animals

from last Friday to Monday, and traced the cases back to the 60 million cans

and pouches of recalled food from Menu Food.

"I was shocked and surprised - acute kidney failure is not a common

problem," veterinarian Cathy Langston told ABC News. "I've already heard

about 200 cases, and so I bet that there are probably going to be

thousands."

So far, the government and the pet food maker, which sells food under 91

brand names, have confirmed 15 deaths. But the investigation to locate the

toxic contaminant that caused the kidney failure in animals had not pointed

to a cause until today.