Monday, April 23, 2007; Posted: 6:50 p.m. (CDT)

Oklahoma City -- The Food and Drug Administration announced more investigations into the massive pet food recall this weekend.  This time they say rice protein could be contaminating the food.  KSBI-TV looks into how veterinarians determine if contaminated foods are in fact causing illness.

It's been one month since more than 100 brands of pet food have been recalled and the Ranchwood Veterinary Hospital in south Oklahoma City is feeling the affects.  Dr. Rick McNeal says they're seeing more clients more often.

"Any sort of vomiting, anything like that, they're taking extremely seriously.  Most are coming in straight away and getting appropriate blood work done," says Dr. McNeal.

Doctors conduct a series of blood tests if poisoning is suspected.  Ranchwood has its own laboratory, where tests are completed within minutes.  Many local veterinarians have to send their blood work to labs in other states, which are now seriously backlogged due to recent high demand.

McNeal says only one case at Ranchwood has been highly suspicious.  The FDA reports 16 deaths nationwide are related to contaminated food.

A group of veterinarians at Michigan State University are now taking a close look at the issue.

"One question that has come up is specifically which cases are involved with the pet food toxin and which ones are not," says Dr. Dalen Agnew with Michigan State University.

They have formed an on line survey to determine how many animals have become ill from the pet food.

"There are always animals that are unfortunately dying everyday from kidney disease.  What we want to do is make sure that when we're trying to figure out what the toxin is that we're only looking at animals that died from the toxin and not animals that may have died from, say, antifreeze poisoning," explains Dr. Agnew.

The survey is designed for veterinarians who believe bad food has caused illness.

In the meantime, Dr. McNeal says have your pet examined if you suspect anything.

"If you fed any of the products listed, you need to discuss it with your veterinarian and find out what the risk really is," says Dr. McNeal.

McNeal also suggests feeding your pets foods that have been highly researched, such as Iams, Science Diet or Eukanuba.

The on line survey is expected to last one month.