Petfoods with plant-derived proteins may also contain more harmful toxins than petfoods with traditional fish and meat proteins, according to new research from the University of Guelph.

"A shift in petfood ingredients is on," says animal and poultry science professor, Trevor Smith, who has spent 35 years researching mycotoxins at Guelph. "Instead of worrying about bacteria spoilage or disease contamination, like we have in the past, we now have to focus on removing mycotoxins."

Smith says pet owners can minimize the risk of mycotoxins by avoiding cheaper petfoods that are more likely to contain vegetable cereals and corn or wheat fillers, and specifically, those with large amounts of rice bran.

"That's the ingredient that's often contaminated," he says. "Although we have no exact numbers, we can estimate that when half of the food is of vegetable origin, there will almost always be some degree of contamination. If the food is mainly of animal origins, the chances of contamination are greatly reduced."

According to Smith, one common mycotoxin found in some grain-based dog and cat foods is deoxynivalenol, which sometimes changes structure when modified by plant enzymes.

He found that adding a specific type of acid to the original enzyme screening can allow manufacturers to detect hidden deoxynivalenol compounds and remove contamination. Smith also says adding yeast to petfood can also help detect mycotoxins because the yeast's fiber binds to the toxins, blocking deoxynivalenol from the pet's blood stream to prevent negative symptoms.

Smith's research is being funded by the Ontario Ministry of Agriculture and Food, the Ministry of Rural Affairs and Alltech Canada Inc. of Guelph.