The ideal nutrient ratio for dog food is a controversial topic. On one side, there are those who advocate that dogs eat zero carbohydrates, while their opponents point out that dogs are not wolves and have adapted to digest starch (Axelsson et al., 2013). There are many strong opinions, but no one really knows the exact ideal canine diet. However, we do have some research in favor of higher protein diets for dogs.
Wild Wolf Diet vs. Modern Dog FoodA 2014 study in the British Journal of Nutrition found that free-living wolves have a protein–fat–carbohydrate ratio of 54:45:1% on a calorie basis (Bosch, Hagen-Plantinga, & Hendriks, 2015). OK, so wolves get 1% of their calories from carbohydrates. Average dry dog foods provide 40-70% of calories in the form of carbohydrates!
Our dogs are getting a lot more carbohydrates from their food than wild wolves choose to eat. Even if dogs have adapted to tolerate a higher carbohydrate level, 40-70 times more than wolves is probably not ideal.
High Carbohydrate Diets and ObesityThe ratio of protein to carbohydrates has an effect on the bacteria in dogs’ intestines (the gut microbiome). A study found that when obese dogs were fed a high protein/low carbohydrate diet, there was an increase in gut bacteria associated with weight maintenance (Li, Lauber, Czarnecki-Maulden, Pan, & Hannah, 2017).
This effect was more prominent in obese dogs than in lean dogs. It would seem that high carbohydrate diets favor a gut microbiome that leads to obesity in some dogs.
Carbohydrates Have Some Benefits
So why do dog food producers put so many carbohydrate ingredients in dog food? There are a few reasons:
- Kibble must contain some carbohydrates to hold its shape. Like a cookie, dry dog food kibbles won’t hold together unless there is some starch in it. That’s why dry dog food tends to have a higher carb content than wet dog food.
- Carbohydrate ingredients generally cost less than meat. Think about the cost of a pound of flour versus a pound of steak. The difference can be tremendous in large-scale production. Including some carbohydrates, ingredients keep the cost affordable for pet owners.
- Carbohydrates combine with meat to create a more palatable texture. Think about the difference between a low-quality, tough cut of beef and meatloaf. The meatloaf is more pleasant to eat because it has a better texture.
Carbohydrate as Filler Calories
Dogs can benefit from a small amount of high-quality carbohydrates in their diet as a source of energy. But when starches contribute the majority of calories in a recipe, they’re acting more like “fillers.”
Overabundant starch isn’t the only “filler” found in your average bag or can of dog food. Let’s take a look at some other sneaky ingredients that cause problems for dogs.
Dog Food “Fillers” to Avoid
A dog food “filler” is an ingredient that has questionable nutritional value. There are many things in the average dog food your dog would never recognize as food, including:
- Meat by-products and grain by-products (chicken by-product, wheat middlings, corn gluten meal, etc.)–cheaper ingredients than meat, used to increase protein and calorie content.
- Starches (green peas, beet pulp, potato, sweet potato, etc.)–these increase calories and allow kibble to hold its shape. Starch provides a ready source of energy, but too much starch doesn’t support good health.
- Soy products (soybean meal, textured vegetable protein/TVP, isolated soy protein, etc.)–a cheaper source of protein than meat.
- Questionable thickeners (carrageenan)–used to improve food texture.
- Food coloring (yellow 6, red 40, etc.)–makes the food more attractive to humans
- Chemically altered proteins (hydrolyzed chicken, hydrolyzed soy protein isolate, etc.)–increase protein content in hypoallergenic dog foods.
Any of these filler ingredients could cause an adverse reaction when ingested by your dog. Anything that irritates the gastrointestinal tract can trigger chronic digestive and skin problems.
Finding a high-protein dog food with no problematic fillers can be a challenge. You could spend hours online or in a boutique pet food store reading labels and still walk away empty-handed. Koha Limited Ingredient Diet for dogs was created to solve this problem. It has no grain, potato, or soy so you can be sure you’re feeding your dog a meat-based diet with no unnecessary fillers.
Axelsson, E., Ratnakumar, A., Arendt, M. L., Maqbool, K., Webster, M. T., Perloski, M., ... & Lindblad-Toh, K. (2013). The genomic signature of dog domestication reveals adaptation to a starch-rich diet. Nature, 495(7441), 360.
Bosch, G., Hagen-Plantinga, E. A., & Hendriks, W. H. (2015). Dietary nutrient profiles of wild wolves: insights for optimal dog nutrition?. British Journal of Nutrition, 113(S1), S40-S54.
Li, Q., Lauber, C. L., Czarnecki-Maulden, G., Pan, Y., & Hannah, S. S. (2017). Effects of the dietary protein and carbohydrate ratio on gut microbiomes in dogs of different body conditions. MBio, 8(1), e01703-16.