(WSBT) It's a good bet most of us don't know the ingredients in the food we eat. It's even less likely we know what's in the treats we feed our dogs.

For anyone who crazy about dogs, it's hard to resist giving them a treat like a rawhide bone. But in the wake of the huge pet food recall, some pet owners are thinking twice about going to the cupboard every time Fido lifts his paw to shake.

“We tested for lead, cadmium, arsenic, nickel, copper, zinc, manganese and selenium,” said John Shafer, a research assistant at Notre Dame. “All of these elements in excessive levels can be harmful — some are harmful in any level. For instance, mercury and arsenic, it’s not good to ingest any of these at all.”

WSBT News sent more than a dozen raw hide bone products to the research experts at Notre Dame. Weeks later, they came back with some surprising results and there seemed to be one common thread.

"If the sample was made in the United States and was from U.S. beef it tended to have lower levels of these toxic elements,” Shafer explained. “If it originated in a foreign country, for instance China or Mexico or Columbia were some of the countries we looked at, they tended to have higher levels.”

Most people probably don't check all of the elements in the food we feed ourselves. Therefore its likely most pet owners never even think of checking for the country a rawhide bone came from.

“That's scary, yeah. I had no idea,” said dog owner Andrea Nissley. “I had no idea any of those contained anything such as that."

Arthur Schroeder is a dog groomer in South Bend. He has one good rule of thumb when it comes to these kinds of treats.

“As far as rawhides and things like that, the rule is ‘Go American,’” Schroeder said. “Most of the other ones are made in South America where the regulations just aren't up to par.”

To put all of this in perspective, WSBT News visited the Midwest headquarters of the American Society for Prevention of Cruelty to Animals in Urbana, Ill. It is the only animal poison control center in the country.

Dr. Safdar Khan said he believes dog lovers would be shocked if they learned the list of ingredients.

“They would probably be surprised, but I think they would be surprised also if they knew what they were eating or what they were drinking, too,” Khan said.

Technically, the elements in the bones tested fell within an acceptable range. However, the ASPCA had this advice: the smaller the dog, the fewer rawhide treats, and never give your dog rawhide treats without keeping an eye on them.

They added it is more likely a dog could choke on one than die of poisoning.