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Are Milk-Bones Toxic To Your Dog?

            There were some Facebook posts back in the Spring about a preservative called BHA in Milk-Bones. The reports were that the preservative could be toxic to your dog. So are they toxic?

            So here’s the hard truth about preservatives, unless you are making your dog’s diet from scratch each meal and serving it immediately, preserving dog food in some way is essential. Without preservation, food quickly spoils and can produce illness rather than the good health we are all looking to provide through optimal nutrition. There are many ways to preserve commercially prepared dog food, each of which has advantages as well as drawbacks.

Artificial Preservatives in Dog Food

            Commonly used artificial preservatives in dry dog foods include ethoxyquin, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). They are very effective at preventing fats from becoming rancid (the primary problem we face in preserving dry dog food) and can greatly extend the product’s shelf life (a year is typical).

            Recently there has been considerable Facebook hype that BHA, the preservative found in Milk-Bones, might cause cancer. From what I’ve seen, the "experts" in the Facebook videos substitute Google searches and scary sound bites for actual science. They are much better videographers than scientists! 

            While researching, I couldn’t find any factual evidence to substantiate claims that BHA, which is commonly used as a preservative in Milk-Bones (and many other dog treats), posed a risk to pets. Decades of research indicated that BHA was generally regarded as safe in both human and animal food products. The only information cited by sites claiming otherwise was speculative and published in 1991that BHA causes cancer.  The FDA regulations still permit BHA use as a fat preservative in food under the assumption it is “generally recognized as safe” in low doses. 

            Milk-Bones response to the claim was:  “We add a very small amount of BHA to our treats as an anti-oxidant that helps to preserve fats and protect against staleness. At these trace amounts, it is completely harmless. We hope this information helps put your reader’s minds at ease.”

            Ethoxyquin is another antioxidant used as a food preservative in certain countries and a pesticide (under commercial names such as "Stop-Scald") to control scald on pears after harvest. It is commonly used as a preservative in pet foods to prevent the rancidification of fats. Ethoxyquin is also commonly used in spices to prevent color loss due to oxidation of the natural carotenoid pigments.

            There has been some speculation that ethoxyquin in pet foods might be responsible for multiple health problems. To date, the U.S. Food and Drug Administration (FDA) have only found a verifiable connection between ethoxyquin and elevations in liver-related enzymes in some animals, but there are no known health consequences from these effects. In 1997, the Center for Veterinary Medicine has asked pet food manufacturers to voluntarily limit ethoxyquin levels to 75 ppm until further evidence is reported. However, most pet foods that contain ethoxyquin have never exceeded this amount.

            Ethoxyquin has been shown to be slightly toxic to fish. Ethoxyquin is allowed in the fishing industry in Norway as a fat stabilizer and is therefore commonly used in food pellets fed to farmed salmon. Ethoxyquin is also commonly used in pellets fed to chickens on chicken farms.

            Ethoxyquin is not permitted for use in Australian foods nor is it approved for use within the European Union.  It is an approved food additive in the United States.

            So, should you buy food with no ethoxyquin and no BHA?  While there is certainly no "smoking gun" out there indicating most pets need to avoid the levels of artificial preservatives currently present in dry food, out of an abundance of caution, many owners understandably prefer to avoid feeding them to their dogs.

Natural Preservatives in Dog Food

            Adding natural substances such as such as vitamin E (mixed tocopherols), vitamin C (ascorbic acid), and plant extracts (e.g., rosemary) to a dry dog food can also prevent fats from becoming rancid. Unfortunately, natural preservatives are effective for shorter periods of time than artificial preservatives, which means naturally preserved foods tend to have a shorter shelf life. As long as you purchase bags well before the "best by" date printed on the label and don’t buy excessively large amounts of food at one time, this shouldn’t be a big concern.

            To determine whether or not a dry dog food contains only natural preservatives, look at the ingredient list. Remember that descriptions like "all natural" on the front of the bag can mean almost anything. If you see ethoxyquin, BHT, and/or BHA in the ingredient list, the food is not naturally preserved.

Preserving Canned Dog Food

            Feeding only canned food is another way to avoid artificial preservatives. The canning process is one of the most effective preservation methods available, so no artificial or natural preservatives need to be included in the food itself. Unopened canned food can last for years when stored in a cool, dry environment, although owners should still observe the “best by” dates that are printed on the label. Canned food is significantly more expensive than dry (and generates more waste) but is another option for owners who want to get the artificial preservatives out of their dog’s diet.


            Of course, what type of preservatives are used in a food is not the only (or even the most important) issue involved in how best to feed dogs. A combination of high quality ingredients that altogether provide balanced nutrition is what is nonnegotiable. It is worth bearing in mind that a lack of preservatives often poses a far greater immediate health risk due to potential growth of mold and bacteria.

            As for Milk-Bones causing cancer, I think most veterinarians would agree that cancer is a complicated problem with multi-factorial origins, including a large heap of genetics and luck of the draw. While nutrition is important for health and all treats should be given in moderation, people shouldn't blame their pet's cancer on a Milk-Bone they fed it in 2005. It's not health food, but it's not exactly a bucket of radioactive sludge either.


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