The Truth About Dog Food Fillers: Good or Bad for Fido?

Many dog food companies proudly state that their high-quality food contains no harmful "fillers." What exactly does this word mean? Is it really as sinister as they make it sound?

The subject is disputed by the dog food community. The Association of American Feed Control Officials, which establishes the recommended nutrient profiles for dog food, doesn’t define what fillers are.

We asked experts for help decoding this industry jargon. Here’s what they said:

What are dog food fillers?

Jonathan Rose, Managing Director at Aurora Pets explains, “Fillers have always been and will probably always be a part of commercial dog foods as they are inexpensive and make a cost-effective production, increase shelf life, and keep the cost of the food down.”

“Generally, a filler is an ingredient that provides little to no nutritional value,” says Krystn Janisse from Homes Alive Pets. “These are typically carbohydrates and can reduce the cost of the components of the food and bulk up some of the guaranteed analysis stats to meet AAFCO regulations.”

What ingredients are commonly considered to be fillers?

Commonly reported as fillers are ingredients like grains, rice, and legumes.

Are filler ingredients good or bad for dogs?

“In smaller quantities,” explains Janisse, “these ingredients often provide nutrients and fiber, but when heavily added, they mostly just take up space and provide texture for dry foods.”

The American Animal Hospital Association publishes a 2017 article “Myth Busters: Corn Edition” about the roles of grains, including corn, in pet food. Here are some key takeaways:

• Corn is a grain.
• When a dog’s diet has lots of grains, protein digestibility is decreased.
• However, when cooked, corn’s cellulose layers are easy to digest.
• How ingredients, including grains, work together to create a nutritional profile is what is important
• Animals need energy. They get it from protein, carbs, and fats. They all work together to create an efficient energy mix. A diet of just one is inefficient.

In the article, Jennifer Larsen, DVM, PhD, DACVN says, “Grains, and any other single category or individual ingredients, are neither good nor bad.”

Let’s take corn for example.

“Fillers are an ingredient added to dog foods that provide no nutritional benefit, but many ingredients that are sometimes called fillers, like corn, actually can provide nutrients to dogs when used appropriately,” says Dr. Jennifer Coates, DVM, who serves on the advisory board for Pup Life Today. Corn provides an essential fatty acid that dogs need and nutrients that are good for dogs, in a balanced diet.

What about food allergies?

In the pet food industry, grains are often put forward as a common allergy, and therefore bad for your pup.

To that point, in the AAHA report, clinical veterinary nutritionist Martha G. Cline from Red Bank Veterinary Hospital in Tinton Fall, N.J., says, “At this time, there is no evidence to support that animals on grain-free diets have less incidence of food allergies than animals on conventional diets. Food allergies, in general, are uncommon.”

Are fillers good or bad for Fido?

As long as dog food is tested to meet the AAFCO’s nutrient profiles for your dog’s developmental stage, then it is safe and healthy to feed to Fido. While looking at pet food labeling can be helpful, it is important to look at nutrients over ingredients, says Ann Wortinger, a veteran veterinary nutritionist. She suggests that pet parents “Look at nutrients, not marketing.” This data is often easiest to glean when looking at the data from feeding trials, which more transparent food companies make public.