Dog Tips

Banned in Human Foods, yet Still Allowed in Your Pet’s Food

This synthetic preservative can be toxic to your pet's liver and kidneys, and has shown to be carcinogenic. While you won't find it listed on food labels, these five common ingredients may contain it. Here's how to know if it's in your pet's food.

Analysis by Dr. Karen Shaw Becker

Apr 28, 2024 • 6 min read

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STORY AT-A-GLANCE

A lawsuit was recently filed against Nestlé Purina for labeling cat food “natural” that contained potentially toxic ingredients, including the synthetic preservative ethoxyquin
Ethoxyquin is linked to cancer and liver and kidney damage, and is banned for use in human foods, but is still allowed in processed pet foods, particularly those containing fish meal
In addition to scientific studies of toxicity, there are countless anecdotal reports — including my own — of pets becoming severely ill as a result of eating diets containing ethoxyquin
Pet parents concerned about ethoxyquin in their dog’s or cat’s food may find it challenging to get a straight answer from pet food manufacturers

Editor's Note: This article is a reprint. It was originally published July 19, 2020.

Recently, two companies filed a lawsuit against Nestlé Purina PetCare for deceptive marketing and sale of cat foods labeled "natural" and "with no artificial preservatives." The plaintiffs, GMO Free USA (doing business as Toxin Free USA) and Clean Label Project charge that lab tests reveal that certain Purina cat foods contain both glyphosate and ethoxyquin, an artificial preservative.¹

The plaintiffs allege that Purina is exploiting pet owner preference for pet foods marketed as "natural," which consumers assume describes products free of pesticides and artificial ingredients.

"Chronic illness has been on the rise, not only in humans, but also in our pets. Amid increasing awareness of the links between synthetic chemicals and chronic health problems, Purina is exploiting consumers' preference for truly natural, toxin-free pet food and must be held accountable for misleading marketing practices," Toxin Free USA executive director, Diana Reeves said in a news release.²

"There has been an increase in the humanization of pet food when it comes to marketing, but there is a disconnect between the marketing and the actual pet food contents. Consumers have a right to know the true contents of the food and products they buy for themselves and their families. This includes their pets," adds Clean Label Project executive director, Jaclyn Bowen.³

Studies have linked glyphosate, found in Bayer-Monsanto's weedkiller Roundup, to cancer, liver and kidney disease, and other adverse health conditions. According to the Corporate Social Responsibility (CSR) Newswire, currently there are an estimated 125,000 pending lawsuits against Bayer-Monsanto alleging Roundup caused Non-Hodgkin lymphoma in plaintiffs.⁴

Monsanto also developed ethoxyquin back in the 1950s for use as a pesticide. It's a synthetic antioxidant and is currently used as a preservative in some ultraprocessed pet foods to prevent rancidity in fats and fat-soluble vitamins. Studies show ethoxyquin can have adverse effects on the liver and toxic effects on both living cells and genetic material.⁵ A 2004 report published by the EPA on ethoxyquin states that:

"The primary target organs affected by ethoxyquin in experimental animals are the liver and the kidneys. Dogs are more susceptible to ethoxyquin toxicity than rats with elevated liver enzymes and microscopic findings in the liver occurring at doses as low as 4 mg/kg/day over a 90-day feeding period."⁶

It's important to note that this study ran only 90 days; no studies are available on the cumulative effects on dogs of ingesting ethoxyquin longer than 90 days. In addition, puppies, working dogs and nursing mother dogs eat more food per body weight per day than the average dog.

First-Hand Accounts of Ethoxyquin Toxicity in Pets

I've actually experienced first-hand the dangers of ethoxyquin poisoning in a dog — my Rottweiler and best friend, Gemini. When Gemini was 7 and I was in my second year of veterinary school, she went into liver failure after consuming food containing ethoxyquin. I had received the food for free from a major pet food manufacturer who was giving it away to veterinary students.

It was determined Gemini's liver failure was caused by the ethoxyquin in that food. Not only was I overcome with grief that I had unintentionally harmed my dog, but I became very angry that a major veterinary line of dog food contained chemicals that had the potential to kill the pets we were learning how to save as vet students.

I committed to never again feed Gemini ultraprocessed dog food. I made a change to her diet literally overnight. I started preparing homemade foods for her and she remained on a homemade diet for the rest of her 13 years of life. It was the beginning of my quest to have clean, healthy, pure foods in the pet food supply chain. That quest continues to this day.

My friend and fellow pet nutrition advocate Susan Thixton, founder of the website TruthAboutPetFood.com, also has a personal ethoxyquin story:

"In 1991 I was a typical pet owner, giving my dogs the most popular pet food sold. Almost overnight a tumor appeared on my dog's pelvic bone. With a trip to the vet, we learned the worst news — bone cancer.

My vet — who knew more about pet food in 1991 than most vets do today — told me her cancer was probably caused by a chemical preservative used in the pet food. He told me the chemical preservative was used to extend the shelf life of the pet food. The preservative was ethoxyquin.

In 1991 I didn't really understand what 'shelf life' was, had no clue what a 'chemical preservative' was, and had never called a pet food company before. But after being told I had two weeks to say goodbye to my best friend, this was something I had to learn more about.

I called this pet food company and only had the nerve to ask one question; 'How long will the dog food stay fresh?' What they told me changed my life forever. This pet food company proudly stated the dog food 'would stay fresh for 25 years.' I had to euthanize my beloved dog 2 weeks later."

The plaintiffs in the lawsuit against Purina published a white paper titled "Ethoxyquin: Is there something fishy about your pet food?" that provides a history of this synthetic antioxidant and its use in pet food.⁷ In their paper, Reeves and Bowen discuss a letter to the FDA Division of Animal Feeds written in 1992 by 30-year veteran veterinarian Dr. Gloria Dodd, graduate of the UC Davis School of Veterinary Medicine.

In her letter, Dodd "… highlighted the epidemic of 'chronic degenerative diseases such as generalized allergies, arthritis, dermatitis, congestive heart failure, kidney failure, liver pathologies, diabetes, tumors and cancer' she observed during her tenure as a veterinarian."⁸

Dodd's letter also pointed out the link between ethoxyquin and the "… marked difference in domestic dog bones, muscles, and overall health compared to Australian pets, who at the time, were still largely being fed fresh meat as opposed to the American pet diet that had largely transitioned to commercial kibble and canned food."⁹

In her letter, Dodd also listed and described case studies and offered her opinion of various outdated Monsanto studies and "erroneous conclusions."

How to Avoid Pet Foods Containing Ethoxyquin

Ethoxyquin is banned for use in human food except in very small quantities allowed as preservatives in spices (e.g., chili powder, which is I recommend only buying organic kitchen spices and herbs). However, it can pass from animal feed to farmed fish, poultry, and eggs, which means humans can still be exposed.

As I mentioned earlier, it's still allowed in pet food — the challenge is determining whether it's in your pet's food. It's rare these days to find ethoxyquin listed on pet food labels, but that doesn't mean it isn't in the finished product. Because ethoxyquin is added before the raw ingredients are shipped to the pet food manufacturers, AAFCO doesn't require that it be listed or disclosed on the product label.

If your dog or cat food contains fish meal, you should assume it contains ethoxyquin not listed on the label, unless the company can provide their vendor's Certificate of Analysis demonstrating it has been tested for and the results are zero.

Call and ask. Poultry meal can also contain ethoxyquin. And according to Thixton, industry insiders have shared with her that additional ingredients, including chicken and beef meals and rendered animal fat, are also sometimes preserved with ethoxyquin.

Thankfully, there are new fresh pet food companies popping up almost weekly that are focused on transparency and will gladly answer all your sourcing and supply chain questions. These gently cooked and raw frozen diets don't contain any added preservatives because the food is made in small batches and immediately frozen, so it's not sitting on a shelf for an extended period of time and therefore doesn't need synthetic additives to prevent rancidity.

If you want ultimate control over the ingredients and sources of the diet your pet eats, homemade meals of fresh, whole food will be your best bet.