We research the ingredients, additives, and preservatives found in commercial pet foods — so you can make safer, more informed choices for your dog or cat.
Many commercial pet foods contain synthetic preservatives and additives that have been linked to cancer in animals. Here are the most important ones to watch for.
Butylated hydroxyanisole and butylated hydroxytoluene are synthetic antioxidants used to preserve fats. The National Toxicology Program lists BHA as a possible human carcinogen, and animal studies show tumor development at high doses.
Originally developed as a pesticide and rubber stabilizer, ethoxyquin is used to preserve fats in pet food. It's banned in human food in the EU and Australia, yet still permitted in US pet food. Linked to liver and kidney damage in dogs.
An antioxidant preservative often used alongside BHA and BHT. Animal studies have associated it with tumor growth. The FDA considers it "generally recognized as safe" for humans at low doses, but safety in pets at cumulative doses is poorly studied.
Red 40, Blue 2, Yellow 5, and Yellow 6 are added purely for visual appeal — pets don't care what color their food is. Some dyes are contaminated with known carcinogens during manufacturing. They offer zero nutritional benefit.
"Meat meal," "poultry by-product meal," and similar terms can legally include euthanized shelter animals, roadkill, and diseased tissue. The rendering process may also concentrate pesticides and drug residues.
Used to keep semi-moist foods soft. While permitted in dog food, it's banned in cat food by the FDA due to its association with Heinz body anemia in cats. Long-term effects in dogs are not fully understood.
Added to improve palatability with no nutritional value. Chronic high-sugar intake contributes to obesity, diabetes, and dental disease — all of which increase cancer risk. Common in cheaper commercial brands.
Used as a color fixative in some pet treats and processed meats. At high temperatures, nitrites can form nitrosamines — compounds classified as probable human carcinogens by the IARC.
Unlabeled fat sources can come from any species and may be preserved with ethoxyquin (which doesn't need to be listed on the label if added by the fat supplier). Always look for named fat sources like "chicken fat."
When reading a pet food label, here's what to look for — and what to put back on the shelf.
Pet food regulations in the United States are surprisingly weak. Ingredients that are banned in human food — or flagged as probable carcinogens — are still legally permitted in the food millions of pets eat every day.
We created PetCarcinogens.com, DogCarcinogens.com, and CatCarcinogens.com to give pet owners a simple, research-backed resource for understanding what's really in their pet's food — and what to do about it.
We are not veterinarians. Always consult your vet before making major changes to your pet's diet. Our goal is simply to give you the information to ask better questions.
A printable cheat sheet you can take to the pet store. We'll email it to you free.