“I never buy at Wal-Mart, I only buy organic and nothing from China, ever!”

This is how Danielle Devereux, whose German Shepherd Sammy is a ravenous consumer of snacks, describes her treat-buying strategy. Sammy prefers his rawhide toys soaked in warm chicken broth first. “As you can guess, he’s a little bit spoiled.”

In Devereux’s remarks, I hear echoes of my own long search for the right dog chew toys. From the time my Shepherd was a wee pup, we combed the pet aisles looking for enticing substitutes for couch and chair leg. She quickly sniffed out her favorite section among the knuckle and femur bones: the bins where the rawhide is cached.

Promoted as an “all natural” treat, rawhide does keep dogs entertained, perhaps even more so in its many basted, twisted, even brightly colored mutations. It’s the equivalent of that gummy-worm-fortified cereal made with real oats that children howl for all the way down the breakfast aisle. Those looking to improve on the bone are like the clever marketers who expertly tune a child’s whining pitch. Your dog would like to convince you that rawhide is primal therapy for his carnivorous soul!

But if rawhide manufacturers were held to the same standards as drug makers, they’d be forced to add an equally long list of warnings to their labels: May cause stomach torsion, choking, vomiting, diarrhea, salmonella poisoning and exposure to various chemical residues.

The closer you look at the rawhide gravy train—its tentacles in China, typically, at one point or another—the more you may want to wean your dog off this dubious by-product.

The Dose Makes the Poison

“The most potent compounds for stimulating the taste buds in dogs, and presumably wolves, are amino acids that taste sweet to humans”—so goes the discussion of canid diet in Wolves, edited by David Mech and Luigi Boitani. Judging by an explosion of patents for flavored rawhide, which include “tastes” such as bubble-gum and hickory, chew-chefs have apparently done their research. However, in creating treats dogs will chomp for hours, they’ve also produced potentially more toxic products. The more dogs lick, chew and swallow the material, the greater their exposure to any contaminants it contains.

In the case of bubble-gum flavoring alone, the Material Safety Data Sheet reveals a toxic confection containing the carcinogen FD&C Red 40, along with preservatives like sodium benzoate. But tracking the effects of chemical exposure is nearly impossible when it’s a matter of slow, low-dose poisoning. The FDA’s veterinary branch, the Center for Veterinary Medicine, checks into pet food additives only after numerous complaints about a particular chemical.

While chews made from rawhide, bone or other animal parts are consumable, and are therefore considered “food” under FDA law, as long as the label contains no reference to nutritional value (such as “high protein”), the agency advises that manufacturers “may not have to follow the AAFCO pet food regulations.”

Producing rawhide begins with the splitting of an animal hide, usually from cattle. The top grain is generally tanned and made into leather products, while the inner portion, in its “raw” state, goes to the dogs. Removing the hair from hides often involves a highly toxic recipe: sodium sulphide liming. A standard practice is to procure rawhide in the “split lime state” as by-products from tanneries, facilities that top the list of U.S. Superfund sites. In the post-tannery stage, hides are washed and whitened using a solution of hydrogen peroxide. And that’s just one step.