By-products in dog food are not inherently bad. They include organ meats like liver, kidneys, and hearts, which are nutrient-dense parts of the animal that dogs would naturally eat. The negative reputation comes mostly from vague labeling and marketing by premium pet food brands, not from the actual nutritional quality of the ingredients.
What “By-Product” Actually Means
The Association of American Feed Control Officials (AAFCO), which sets ingredient definitions for pet food in the U.S., defines by-products as “secondary products produced in addition to the principal product.” In practical terms, these are the parts left over after the cuts of meat sold for human consumption are removed. That includes internal organs, blood, bone, and sometimes meat that didn’t meet the cosmetic standards for grocery store shelves but is perfectly safe and nutritious.
The key distinction is between “meat by-products” and “by-product meal.” Meat by-products are the fresh or frozen organ meats and tissues. By-product meal is the same material after it has been rendered, meaning cooked at high temperatures and dried into a concentrated powder. Both can appear on ingredient labels, and both provide protein, fat, and micronutrients. Organ meats like liver are among the most nutrient-rich foods a dog can eat, packed with iron, B vitamins, and vitamin A in concentrations that muscle meat can’t match.
Why By-Products Have a Bad Reputation
Much of the backlash against by-products traces back to marketing. As the premium pet food market grew, brands found they could charge more by advertising “real chicken” or “whole meat first” on their labels. By-products became shorthand for low quality, even though the organs and tissues they contain are nutritionally valuable. The word itself sounds industrial, which doesn’t help.
There’s also a common concern about what by-products might include. Some pet owners worry that by-products could contain hooves, hair, feathers, or meat from sick animals. AAFCO’s definitions do exclude hair, hooves, horns, and teeth from meat by-products. And federal law requires all animal foods to be safe, produced under sanitary conditions, and free of harmful substances. The FDA and state regulators conduct risk-based inspections of pet food manufacturing facilities to enforce these standards.
Are By-Products Safe?
Yes. Rendered by-product ingredients go through a cooking process at temperatures high enough and for long enough to eliminate biological hazards like Salmonella and E. coli. Research published in the Journal of Animal Science confirms that rendered products are cooked at higher temperatures for longer times than necessary for basic food safety. Canned pet foods face additional federal regulations requiring processing that eliminates viable microorganisms.
The FDA holds pet food to the same foundational safety standard as human food: it must be safe to eat, produced under sanitary conditions, contain no harmful substances, and be truthfully labeled. That applies whether the food contains whole chicken breast or chicken by-product meal.
Nutritional Value Compared to Whole Meat
A common misconception is that by-products are nutritionally inferior to whole muscle meat. In many cases, the opposite is true. Liver contains far more vitamin A, iron, and B12 than chicken breast. Kidney is rich in selenium and riboflavin. Heart is an excellent source of taurine, an amino acid critical for your dog’s cardiac health. These are the same organs that wolves and wild canids eat first when they make a kill.
By-product meal, because it has been dried and concentrated, often contains more protein per gram than fresh whole meat. When you see “chicken” listed as the first ingredient in a dog food, that weight includes roughly 70% water. Once cooked, the actual protein contribution may be less than a by-product meal listed second or third on the label. This doesn’t mean one is always better than the other, but it does mean that ingredient order on a label can be misleading.
When By-Products Are Worth Avoiding
Not all by-product ingredients are created equal, and the real issue is transparency. A label that says “poultry by-product meal” without specifying the species (chicken, turkey, duck) gives you less information about what your dog is eating. If your dog has a known food sensitivity, vague sourcing makes it harder to identify and eliminate triggers. In those cases, choosing foods with named protein sources, whether whole meat or named by-product meal like “chicken by-product meal,” gives you more control.
Quality also varies between manufacturers. A reputable company sourcing liver, hearts, and kidneys from inspected facilities produces a very different product than one using the lowest-cost rendered material available. Looking for brands that specify which organs are included, or that meet AAFCO nutrient profiles through feeding trials rather than just formulation, gives you a better signal of quality than simply avoiding by-products altogether.
The Environmental Angle
There’s a sustainability argument for by-products that often gets overlooked. Roughly 38% of a beef carcass, 20% of pork, and 19% of chicken consists of viscera and blood that isn’t used for human food. If those parts weren’t channeled into pet food and other animal feed, they would become waste. Using by-products in dog food converts what would otherwise be a disposal problem into a nutritional resource, reducing the overall environmental footprint of meat production. Only about 13% of all rendered by-products go to pet food; the rest supports animal agriculture, biodiesel, and other industries.
Choosing a dog food that uses by-products effectively means your pet’s diet isn’t competing for the same cuts of meat that end up on your dinner table. For owners concerned about the environmental impact of feeding their dogs, by-products are one of the more practical ways to reduce that footprint without switching to alternative protein sources like insects or plant-based formulas.