What's Really in Your Dog's Treats?

Most dog owners trust the brands on pet store shelves. But a growing body of research from the National Institutes of Health, veterinary toxicology labs, and European food safety authorities suggests several common treat ingredients deserve closer scrutiny.

This isn't about fear. It's about informed choices. Below, we examine five categories of ingredients found in widely available dog treats, alongside the published research on each one. Every claim links directly to its source.

"You wouldn't eat something you couldn't identify. Why should your dog?"

The 5 Ingredients Worth Questioning

BHA & BHT

Synthetic Preservatives

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are petroleum-derived antioxidants added to fats and oils to prevent rancidity. They've been used in food manufacturing since 1947.

The U.S. National Toxicology Program (NTP) classifies BHA as "reasonably anticipated to be a human carcinogen" based on sufficient evidence from animal studies, including tumors in rats, mice, and hamsters. BHA appears on California's Proposition 65 list of chemicals known to the state to cause cancer.

The International Agency for Research on Cancer (IARC) classifies BHA as Group 2B, "possibly carcinogenic to humans." A 2023 review in Regulatory Toxicology and Pharmacology documented evidence of thyroid system damage, metabolic disorders, neurotoxicity, and carcinogenesis across multiple studies.

NIH 15th Report on Carcinogens → 2023 Health Risks Review →

How to spot it: Look for "BHA" or "BHT" in the ingredient list, or the phrase "BHA added to preserve freshness" near the bottom of the label. Common in mass-market biscuits, jerky-style treats, and dry foods with long shelf lives.

Propylene Glycol

Moisture-Retaining Chemical

Propylene glycol is a synthetic compound used as a humectant in semi-moist dog treats and foods to maintain softness and prevent drying. It's chemically related to ethylene glycol, the primary component of antifreeze, though less acutely toxic.

According to the Merck Veterinary Manual, propylene glycol ingestion can produce symptoms similar to the acute phase of ethylene glycol toxicosis in pets. The oral LD50 (median lethal dose) in dogs is approximately 9 mL/kg body weight.

The FDA banned propylene glycol from cat food in 1994 after research demonstrated it causes Heinz body formation and decreased red blood cell survival, even at concentrations found in commercial diets. While dogs are less sensitive than cats, propylene glycol is listed among the causes of canine Heinz body anemia in veterinary pathology references.

Merck Veterinary Manual → PubMed: Heinz Body Formation →

How to spot it: Look for "propylene glycol" in the ingredient list. Most common in soft, chewy, or semi-moist treats and foods that stay pliable in the bag without refrigeration.

Artificial Colors (Red 40, Yellow 5, Yellow 6)

Synthetic Petroleum-Derived Dyes

Synthetic food dyes are added to treats purely for visual appeal. Dogs don't select food by color. These dyes provide zero nutritional value and exist solely to influence the human buyer's perception.

A landmark 2007 randomized, double-blinded, placebo-controlled trial published in The Lancet by University of Southampton researchers found that mixtures of artificial food colors and the preservative sodium benzoate increased hyperactivity in children from the general population. This study led the EU to mandate warning labels on foods containing these dyes.

A subsequent meta-analysis published in the Journal of the American Academy of Child & Adolescent Psychiatry (2012) confirmed a statistically significant effect of synthetic food colors on behavioral symptoms. The FDA last conducted a comprehensive safety review of Red 40 upon its approval in 1971.

McCann et al., Lancet 2007 → Meta-Analysis: Food Colors & ADHD →

How to spot it: Look for "Red 40," "Yellow 5," "Yellow 6," "Blue 1," or any "FD&C" color on the label. If the treat is an unnaturally vivid color (bright red, neon orange), it almost certainly contains synthetic dyes.

Corn, Wheat & Soy Fillers

Low-Cost Bulk Ingredients

Corn, wheat, and soy are among the most commonly reported food allergens in dogs. They're used primarily as inexpensive binders and carbohydrate sources, not because they serve the nutritional needs of a carnivore's digestive system.

Veterinary dermatology research identifies beef, dairy, wheat, and corn among the most frequently implicated ingredients in canine adverse food reactions. A 2016 systematic review in BMC Veterinary Research analyzing 297 dogs found that wheat and corn were among the top allergens triggering cutaneous adverse food reactions.

These fillers often constitute the majority of a treat's weight while contributing minimal biologically appropriate nutrition for dogs. The presence of these ingredients typically indicates cost optimization over nutritional value.

BMC Vet Research: Food Allergens →

How to spot it: Check whether corn, wheat, soy, or "grain" appears in the first five ingredients. If it does, the treat is mostly filler by weight. Present in the vast majority of grocery-store treats.

"Meat Meal" & Unspecified Protein

Rendered Mystery Protein

When a label says "meat meal," "meat by-products," or "animal digest" without naming the species, there is no way to verify the source. The rendering process can include material from animals that were dead, dying, diseased, or disabled prior to slaughter, sometimes referred to as "4D" meat in the industry.

AAFCO (Association of American Feed Control Officials) defines "meat meal" as the rendered product from mammal tissues, exclusive of blood, hair, hoof, hide trimmings, manure, and stomach contents, but the species is not required to be identified. This means the protein source can change between batches without label changes.

This lack of traceability makes it impossible to identify allergens, verify sourcing practices, or ensure consistency. Named, single-source proteins (e.g., "chicken liver" or "beef heart") provide full transparency about what your dog is consuming.

How to spot it: Look for vague terms like "meat meal," "meat by-products," "animal fat," or "animal digest." If the label doesn't name the specific animal (chicken, beef, lamb), the source is unverifiable.

What to Look For Instead

The research points in a clear direction: simpler is better. When evaluating any treat, look for these qualities:

Signs of a Clean Treat

Single, named ingredient: "Beef liver" or "Kangaroo heart," not "meat meal" or "animal by-products"
No synthetic preservatives: Air-dried, freeze-dried, or naturally preserved with Vitamin E (mixed tocopherols) or rosemary extract
Human-grade sourcing: Processed in facilities that meet human food safety standards
Traceable origin: You can identify the country, the animal, and the cut of meat
No artificial colors or flavors: If a treat needs dye to look appetizing, what does that tell you about the meat?