Another pet food myth that continues to abound is that the presence of certain preservatives causes cancer in our pets.   This tall tale has been around since I first started working in the pet industry way back in the late 1980s!  The controversy centers on three compounds, BHA, BHT, and ethoxyquin.

I recall hearing how the preservative, ethoxyquin, had been implicated by dog owners as causing allergic reactions, skin problems and, of course, cancer.   There was little to no scientific evidence to support these claims, yet any pet food manufacturer who utilized ethoxyquin was often shunned.   I distinctly remember this because the store I worked for sold Iams and Eukanuba products as our sole food.  (This was back before Iams was purchased by Procter and Gamble).

Ethoxyquin has been added to pet foods and animal feeds for more than 35 years.  It is very useful to help stabilize and protect fats and oils during the high temperatures needed to cook and extrude many pet foods.  Without good preservation, the fats will go rancid causing the food to lose calories and certain fat soluble vitamins.  The FDA did allow up to 150 parts per million(ppm) of ethoxyquin in pets foods but has asked pet food manufacturers to reduce that to less than 75 ppm.   It is a rare pet food that exceeds the 75 ppm level.  

BHA and BHT (butylated hydroxyanisole and butylated hydroxytoluene) are two other preservatives that get a lot of bad press despite the fact that a good percentage of us eat these almost every day.  These preservatives can be found in our butter, cereals, baked goods, snack foods, and even my precious beer!   Both of these compounds keep fats from becoming rancid, thus protecting the food.  The FDA allows up to 200 ppm of the fat or oil content of the food of BHA or BHT.  Opponents of BHA/BHT often quote a study in rats in which BHA caused cancer of the forestomach in rats.   Since we don’t have a forestomach, the conclusions that BHA will cause cancer in us are not perfectly valid.  Furthermore, the FDA has said that we would need to ingest 125-150 times as much BHA as most people currently do in order for it to potentially cause any problems.  So, while the FDA does admit that these products need more research, they are generally regarded as safe (GRAS) in the levels currently found in our foods.   Pet foods use much lower levels.

I think the more telling argument for me is “why would a pet food company purposefully add something known to cause cancer to their food?”  Surely, all of these companies have intelligent, well paid attorneys who will remind them that the American consumer is savvy and won’t tolerate this kind of deliberate alteration of their pet’s food.

Now, other preservatives are being used in ever-increasing amounts.   Vitamin E, citric acid and mixed tocopherols are considered to be a more “natural” solution to the preservative issue.  There is some concern over shelf life of foods preserved this way.

My final point is to also toss the ball back into the court of individuals who originally propagated their version of issues with BHA, BHT, and ethoxyquin.  Did anyone ever look at the breeds and lineages of the pets who were cancer-stricken?   Was there a potential for a genetic component or even a family sensitivity to these compounds? 
                                                                                                         By Thomas Dock, Vet. Technician