Is This Pet Food Vilification Ever Justified, or Just a Bunch of Hot Air?

Pet Food Fillers

Story at-a-glance

  • The commercial pet food industry is increasingly finding itself in the uncomfortable position of trying to defend many of the ingredients it uses. As pet owners grow more nutrition-savvy and holistic veterinarians continue to promote the benefits of species-appropriate diets for cats and dogs, the purveyors of processed pet food are scrambling to make a case for themselves.
  • In a recent article in a pet food industry journal, the author took on the “vilification” of fillers in commercial pet food. He lamented the fact that “informational websites” and even pet food manufacturers themselves via their marketing campaigns are giving fillers a bad rap.
  • The author makes the point that the term “filler” has no legal definition, so therefore what constitutes a filler is open to interpretation. We disagree. It’s actually a snap to identify filler-laden pet food with just a rudimentary understanding of the nutritional requirements of dogs and cats.
  • Pet food fillers typically have four things in common: they are cost effective for the pet food producer, useful in turning raw ingredients into processed pet diets, beneficial in stabilizing products for shipment and storage, and not species-appropriate nutrition for cats and dogs.
  • Fillers in commercial pet food are there for the benefit of the manufacturers, not for the animals who will eat the stuff. The other benefit of these formulas is that they are affordable. We recommend that as the loving guardian of a dog or cat, you feed the highest quality diet you can reasonably afford, since what your pet eats directly contributes to his overall health and longevity.

By Dr. Becker

I ran across an article in a pet food industry journal recently that questioned whether fillers in pet food are unfairly maligned, not only by "informational websites" like this one, but also by pet food manufacturers who use phrases like "contains no fillers" to market their products.

The author of the article observes that the overriding message is that fillers are bad news and should be avoided. He then poses the question, "But, is this a legitimate warning or are we unwittingly being sensitized to select against a broad category of potentially beneficial ingredients?"

Defining Fillers in Processed Pet Food

For those of you unfamiliar with pet food industry-speak, "potentially beneficial ingredients" can be loosely defined as ingredients added to processed dog or cat food that are:

  • Cost effective for the pet food producer
  • Useful to the manufacturer in turning raw ingredients into processed pet diets
  • Beneficial in stabilizing products for shipment and storage
  • Not species-appropriate nutrition for pets

If the "potentially beneficial ingredient" also offers the manufacturer an opportunity to market the product to appeal to pet owners hoping to offer a healthy, high quality diet to their dog or cat, it's an added bonus. For example, pet food producers realize consumers have grown savvy about the need for protein in their carnivorous pet's diets. The only protein truly beneficial for cats and dogs is animal protein, but that doesn't stop pet food companies from adding ingredients like feather meal or soy protein concentrate to not only increase the protein percentage of the formula, but also give the product "high protein" bragging rights.

The article author goes on to say that what constitutes a "filler" is open to interpretation, because the term isn't a defined ingredient by any regulatory agency. But the fact is, it's not at all complicated to find the fillers in processed pet food.

Take a look at the ingredients in these two commercial dog foods. Which do you suppose contains more fillers?

Raw Dog Food, Sold Frozen 'Premium' Dry Dog Food
Free-Range Meat = 69%
chicken meat including bone, chicken gizzards, chicken hearts and chicken livers

Organic Vegetables = 29.3%
carrots. squash, yams, zucchini, celery, romaine, parsley, apple cider vinegar

Special Nutrient Mix = 1.7%
kelp, sea salt, inulin, zinc, copper and iron amino acid chelates, vitamin E
Ground yellow corn, corn gluten meal, whole wheat flour, animal fat preserved with mixed-tocopherols (form of Vitamin E), soy protein concentrate, soy flour, water, rice flour, pearled barley, sugar, tricalcium phosphate, propylene glycol, animal digest, dicalcium phosphate, salt, phosphoric acid, sorbic acid (a preservative), calcium carbonate, potassium chloride, L-Lysine monohydrochloride, dried spinach, dried apples, dried sweet potatoes, choline chloride, calcium propionate (a preservative), added color (Red 40, Yellow 5, Blue 2, Yellow 6), Vitamin E supplement, zinc sulfate, ferrous sulfate, manganese sulfate, niacin, Vitamin A supplement, copper sulfate, Vitamin B-12 supplement, DL-Methionine, calcium pantothenate, thiamine mononitrate, garlic oil, pyridoxine hydrochloride, riboflavin supplement, Vitamin D-3 supplement, calcium iodate, menadione sodium bisulfite complex (source of Vitamin K activity), folic acid, biotin, sodium selenite


Another reason for the laundry list of ingredients in the dry food above is that in order to meet AAFCO nutritional standards, pet food manufacturers must add back in the vitamins and minerals that either aren't found in a limited ingredient list (raw food, above), aren't found in a long list of low quality ingredients (dry food, above), or are destroyed during the extreme processing that these pet foods undergo (dry food, above).

Fillers Can Be a Special Problem for Cats

Unlike dogs, who are scavenging carnivores that can survive (but not thrive) eating grain-filled diets, cats are obligate carnivores, which means they need animal meat to stay alive.

Let's do another ingredient comparison, this time looking at a raw cat food and a canned cat food marketed as containing "natural ingredients in perfect balance."

Raw Cat Food, Sold Frozen 'Premium' Canned Cat Food
Ingredients Ingredients
Free Range Chicken, Ground Chicken Bone, Chicken Hearts, Chicken Liver, Psyllium, Kelp, Salmon Oil, Catnip Turkey, Turkey Broth, Chicken Broth, Water, Pork Liver, Brown Rice, Carrots, Pork Plasma, Potato Starch, Rice Starch Modified, Spinach, Dried Egg Whites, Dextrose, Oat Fiber, Pea Protein, Pea Fiber, Chicken Liver Flavor, Calcium Carbonate, Potassium Chloride, Sodium Phosphate, Vitamins (Vitamin E Supplement, L-Ascorbyl-2-Polyphosphate (source of vitamin C), Thiamine Mononitrate, Niacin, d-Calcium Pantothenate, Biotin, Vitamin A Acetate, Pyridoxine Hydrochloride, Riboflavin Supplement, Vitamin B12 Supplement, Vitamin D3 Supplement, Folic Acid, Menadione Sodium Bisufite Complex (source of vitamin K3)), Taurine, Guar Gum, Minerals (Ferrous Sulfate, Zinc Oxide, Copper Proteinate, Manganous Sulfate, Potassium Iodide), Choline Chloride, Caramel (color), DL-Methionine, Beta-Carotene


Once again, it's a piece of cake to pick the formula loaded with fillers. As with the dog food examples, both cat foods meet AAFCO nutritional standards. But it's again notable just how many supplements the producer of the canned formula must add back in to meet those requirements.

Don't Be Fooled By Nonsensical Discussions of 'Good' vs. 'Bad' Pet Food Fillers

The bottom line is this: fillers in commercial pet food are there for the benefit of the manufacturers, not for the animals who will be fed their formulas. The other benefit of these formulas is that they are affordable for most pet owners.

Your job as the loving guardian of a dog or cat is to feed the highest quality diet you can reasonably afford, since what your pet eats directly contributes to how long he will live, and how healthy he will remain throughout his lifetime.

For more information and tips on how to choose the best food for your pet:


+ Sources and References