Preserve me Forever!

Updated on October 27, 2021

Preserve me Forever …

McKibble and McCan may need to sit on store shelves for months or even years. Preservatives can be either natural … or artificial. Natural preservatives are usually made from anti-oxidants… like vitamins C or E. Consumers see them printed on a dog food’s ingredients list using some form of the word “tocopherol” or “ascorbate” (example: “chicken fat preserved with alpha-tocopherol”).

Artificial preservatives differ, adding a notable risk of toxicity to any dog food. Pet parents should question the presence of these additives, and assume the choice is made owing to “least cost mix” protocols. An example: the humecant (moisture preservative) propylene glycol is a common (cost effective) preservative in dry foods. Another conventional dog food preservative, ethoxyquin, is used as an industrial pesticide, and as a hardening agent in the manufacture of synthetic rubber. The World Health Organization openly names both butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) as probable carcinogens (cancer-causing compounds). BHT can also be found in cosmetics, pharmaceuticals, jet fuels, rubber, petroleum products, electrical transformer oil and embalming fluid.

Fat and oil preservatives added to dog foods to increase shelf life include tertiary butylhydroquinone (TBHQ)… but also used to stabilize certain explosive compounds… and to make varnishes, lacquers and resins. Sadly, many dog guardians serve up these chemicals at every meal over their dog’s lifetime.

  • Butylated Hydroxytoluene (BHT): BHT is an antioxidant preservative that preserves fat and prevents food from going rancid. BHT is a carcinogenic has been linked to cancer in lab animals.
  • Butylated Hydroxyanisole (BHA): BHA works similarly to BHT and is often used in conjunction. It is an antioxidant preservative that prevents both fats and oils from spoiling. BHA, like BHT, has been linked to cancer.
  • Ethoxyquin: Ethoxyquin is a banned preservative in Australia and the EU. Its primary use is as a pesticide but it has been used to preserve foods from spoiling. Ethoxyquin is linked to kidney and bladder failure, digestive issues, and stomach and colon tumours.
  • Propylene Glycol (PG): PG is a chemical found in antifreeze that is used in food to stabilize vitamins and add texture and sweetness. PG has been linked to liver problems and cellular damage.
  • Tertiary Butylhydroquinone (TBHQ): TBHQ is another fat preservative that helps extend shelf life. The World Health Organization has found that prolonged exposure to TBHQ causes cancer and cellular damage.
  • Propyl Gallate: Propyl Gallate is a fat stabilizer been banned from the United Kingdom because it is linked to blood disorders. Studies have also linked propyl gallate to allergies, skin irritation, and cancer.

Though synthetic preservatives were once – as recently as 20 years ago – the usual preservative found in all dry dog foods, today, they appear only on the labels of low-cost and lower-quality products. Pet food companies appreciate the fact that artificial preservatives are less expensive, and they preserve food longer and more reliably than their natural counterparts.

It is possible, however, for pet foods to contain ethoxyquin or other artificial preservatives even if those substances don’t appear on the list of ingredients.

Preservatives Not on the Label

It’s the fat in meat or poultry meal that needs protection from oxidation. Animal protein meals (i.e., “chicken meal”, “lamb meal”, etc.) usually contain 10 to 14 percent fat. While the preservative used to protect the major fat sources in a dog food (such as “chicken fat”) must be declared on pet food labels, the amount of preservative used in protein meals is generally considered low enough to meet the definition of an “incidental additive”, which is not required to appear on the product label. At least, that’s one explanation for why the preservatives used in protein meals don’t have to appear on pet food labels.

A more prevalent explanation is that there is no legal requirement for pet food makers to disclose substances that were added to an ingredient before it reaches the pet food manufacturing plant. We’ve been told countless times that a pet food maker is responsible for disclosing only the ingredients they themselves mix in during the manufacture of the pet food. In other words, “We didn’t put ethoxyquin in the fish meal; it was already there when we bought the meal! And because we didn’t put ethoxyquin in our pet food, we don’t have to list it among our products’ ingredients.

We’ve heard this claim so many times, in fact, that we were surprised to learn that it’s not wholly accurate. Dave Dzanis, DVM, PhD, DACVN, a consultant on animal nutrition, labelling, and regulation, writes in his December 2009 column in the trade publication Petfood Industry:

For a labeling exemption as an ‘incidental additive’ to apply, the level in the final product would have to be low enough to where it no longer had any technical or functional effect [21 CFR 501.100(a)(3)(i)]. Considering that fish meal processors may add 1,000 ppm or more, the residual amount of ethoxyquin in the petfood still could be functional, hence would have to be declared.

Also, FDA regulation 21 CFR 573.380 expressly specifies that any animal feed containing ethoxyquin must declare it, which is unique language compared to the codified requirements for other approved food additives. That statement can be interpreted as superseding any labeling exemption. In fact, if memory serves me, in the 1990s FDA did advise that ethoxyquin must be declared whether added directly or indirectly, irrespective of source or level.

We’re not sure how this information can be reconciled with the fact that many pet food companies use fish meal that has been preserved with ethoxyquin, yet ethoxyquin does not appear on the label. Perhaps most companies do not fully understand or have a different interpretation of these rules, and the regulations are simply not enforced?

A Closer Look at Ethoxyquin

Ethoxyquin is a chemical antioxidant and was approved as a pet food additive in 1959. It is used to preserve certain spices (chili powder, paprika, and ground chili only), and is also used as a pesticide and a rubber preservative. Residual levels from animal feed are allowed in meat, poultry, and eggs for human consumption.

Due to consumer outcry, ethoxyquin is very rarely seen on the label of even very low-quality dog foods. But that doesn’t mean the food is ethoxyquin-free.

The US FDA’s Center for Veterinary Medicine (CVM) began receiving reports in 1988 of health issues that pet owners and some veterinarians suspected could be linked to ethoxyquin in pet foods, such as allergic reactions, skin problems, major organ failure, behaviour problems, and cancer. Studies done by Monsanto (the manufacturer of ethoxyquin) at the request of the US CVM, showed dose-dependent effects on liver enzymes and pigment. As a result, in 1997 the US CVM asked the pet food industry to voluntarily lower the maximum level of ethoxyquin in dog foods from 150 ppm (parts per million) to 75 ppm. It said that most pet foods never exceeded the lower amount, even before this recommended change.

Is this level safe? According to a document produced by the US Environmental Protection Agency (EPA), “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.” The “4 mg/kg” means 4 mg ethoxyquin per kilogram of the dog’s body weight (not the weight of the food).

Per CVM calculations, 4 mg/kg body weight is the equivalent of 160 ppm in food, just barely above the upper limit that is still allowed in pet food. It’s possible that longer-term ingestion could reduce the amount needed to cause adverse effects and increase the potential for harm. In addition, dogs who eat more food in relation to their body weight, such as puppies, nursing females, and working or other very active dogs, are at risk of exceeding the amount known to cause liver damage.

Let’s look at the fish meal that is processed at sea and treated with ethoxyquin at time of production. US Coast Guard regulations say that this fish meal must contain at least 100 ppm ethoxyquin at time of shipment. It’s questionable, though, how much ethoxyquin remains in a finished pet food made with this fish meal. The amount of fish meal used, and the method and temperature of the dog food’s manufacture will affect the amount of ethoxyquin present in the final product. We’ve seen claims from companies whose dog foods contain fish meal preserved with ethoxyquin that the foods contain 5 ppm or less ethoxyquin.

Is this lower level safe? No one knows for sure, but it’s certainly less toxic than the amounts that the US FDA allows in pet food. And it’s within the limits allowed in some human foods (0.5 to 5 ppm in meat and fat, with higher amounts allowed for spices).

The US FDA and pet food industry officials defend the use of ethoxyquin, saying that ethoxyquin is safer than rancid fats. While this may be true, artificial preservatives are not the only way to prevent rancidity. In addition, if ethoxyquin is safe, why is it not permitted to be added to human foods (other than three spices), and why is the acceptable level for pet foods 50 times the residual amount allowed in human food?

Other Artificial Preservatives

Pet parents and consumer advocates suspect ethoxyquin of causing cancer, though studies don’t seem to bear that out except at very high levels (5,000 ppm or more). On this point, the US EPA concluded, “potential cancer risk is below the Agency’s level of concern.” The artificial preservatives BHA and BHT are considered more likely carcinogens.

Both have been linked to cancer in laboratory animals; it’s unknown whether they cause the same in people and dogs. There is evidence that certain people may have difficulty metabolizing BHA and BHT, resulting in health and behaviour changes. Again, we don’t know if the same is true for our dogs.

Yet Another Matter of Trust?

How then can a consumer find out if their dog’s food contains ethoxyquin, BHA, BHT, or other artificial preservatives? Unfortunately, there are no easy answers. You can contact the companies or check their websites, in an effort to find out if they use only naturally preserved meat meals in their foods. Some companies have started making “ethoxyquin-free” claims on their labels and product literature. One would have to trust the company’s answer, though; short of conducting expensive laboratory tests, there is no way to verify these claims. And even usually trustworthy companies can be duped by a contract manufacturer or ingredient supplier.

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