Can Dogs Eat Carbohydrates and Starches? What the Science Says

Ask the internet whether dogs can eat carbohydrates and you'll find passionate arguments on both sides — usually from pet food brands with a financial interest in the answer. Here's what the actual science says: yes, dogs can eat carbohydrates, they've been eating them for thousands of years, and their ability to digest starch is one of the key genetic adaptations that distinguishes them from wolves.

The Genomic Evidence: Dogs Are Not Wolves

The most compelling argument for dogs' ability to handle carbohydrates isn't a theory — it's written in their DNA. In 2013, researchers conducted whole-genome sequencing of dogs and wolves to identify how the two species diverged genetically. Of the 36 regions of the genome that distinguish dogs from wolves, 10 genes are specifically related to starch digestion and fat metabolism — an entire pathway selectively altered during domestication (Axelsson et al., Nature, 2013).

The differences are striking at the molecular level. Dogs have 4 to 30 copies of the gene that produces pancreatic amylase (AMY2B), the enzyme responsible for breaking starch into sugars — compared to just 2 copies in wolves. On average, this represents a roughly sevenfold copy number expansion in dogs relative to wolves, and research confirms that higher AMY2B copy numbers are associated with higher amylase activity — meaning dogs produce substantially more of the enzyme that breaks down starch. The study also identified selective changes in the genes controlling the conversion of maltose to glucose (MGAM) and the transport of glucose across the small intestinal membrane (SGLT1) — suggesting that an entire metabolic pathway was reworked, not just a single gene.

The leading hypothesis is that this adaptation occurred as wolves began scavenging food waste near early human agricultural settlements. Dogs that could extract energy from starch-rich scraps had a survival advantage — and over thousands of years, that capacity became deeply embedded in canine biology. By 7,000 BC, archaeological evidence shows that domesticated dogs in parts of northern China were deriving 65–90% of their dietary energy from millet alone.

In other words, carbohydrate digestion is not a modern compromise in dog food — it is one of the defining features of dog evolution.

Where the "Grain-Free" Trend Comes From

The idea that dogs should eat like wolves — high meat, no grains — became popular in the early 2010s and closely tracks the rise of paleo and ancestral eating trends in human nutrition. It is a marketing position, not a scientific one. The dog-as-wolf framing appeals intuitively to pet owners who want to feed their pets "naturally," but it misrepresents the evolutionary biology of domesticated dogs, which diverged from wolves genetically, behaviorally, and metabolically over thousands of years.

Plant-based ingredients have been included in commercial dog food since the inception of the industry, and the average companion dog today gets most of its daily energy from plant-based carbohydrates. This is not a new development — it reflects both the science and the long history of how humans and dogs have eaten alongside each other.

There is currently no peer-reviewed evidence that low-carbohydrate diets provide health benefits for dogs. In fact, the FDA has been investigating a potential association between grain-free diets high in legumes and dilated cardiomyopathy (DCM) in dogs since 2018 — though causation has not been established. The association is specifically with grain-free diets, not with grain-inclusive ones.

What AAFCO Says About Carbohydrates

AAFCO — the Association of American Feed Control Officials — is the regulatory body that establishes nutritional adequacy standards for pet foods in the US. For adult maintenance diets, AAFCO sets minimum thresholds for protein (18%) and fat (5.5%), but establishes no minimum or required carbohydrate content. Carbohydrates are not classified as an essential nutrient for dogs, in the sense that dogs can synthesize glucose from protein through gluconeogenesis if needed.

What this means in practice is that carbohydrates are a flexible and efficient energy source in canine diets — one that dogs are biologically well-equipped to use, even if it's not mandated. Most conventional dog foods derive the majority of their calories from carbohydrates, and dogs in those diets are nutritionally complete when the overall formula meets AAFCO standards.

Complex Carbs vs. Simple Carbs: Quality Matters

Not all carbohydrates are equal, and this is where ingredient quality becomes relevant. Complex carbohydrates — from whole grains, legumes, and vegetables — come with fiber, micronutrients, and functional compounds that refined or processed starches don't provide. Soluble fiber from sources like oats and pumpkin supports gut health and motility. Omega-3 fatty acids in flaxseeds contribute to skin, coat, and inflammatory health. The glycemic index also varies significantly: low-GI carbohydrates like oats release energy more slowly, supporting stable blood sugar rather than the spike-and-crash associated with highly refined starches.

Petaluma uses organic oats, organic barley, and organic chickpeas as its primary carbohydrate sources — all low-GI whole foods with meaningful fiber content and a range of micronutrients. This is meaningfully different from refined corn starch or white rice used in lower-quality formulas, and it's why the source of carbohydrates matters as much as whether they're present at all.

Petaluma also oven-bakes its food rather than using high-pressure extrusion, which gelatinizes starches into fast-release carbohydrates and raises the glycemic index. Baking preserves a better balance of slow- and fast-release carbohydrates — one of the practical advantages of the baked format for dogs that benefit from more stable blood sugar.

The Real Weight Management Issue

The most significant diet-related health problem facing dogs is not carbohydrate intake — it's calorie excess. An estimated 59% of dogs in the US are overweight or obese (Association for Pet Obesity Prevention, 2022), and the driver is total caloric intake relative to energy demand, not the macronutrient source of those calories. Carbohydrates, protein, and fat all contribute to total caloric load. Reducing carbohydrates while overfeeding protein and fat does not result in weight loss.

The most impactful thing a dog owner can do for their dog's long-term health is measure portions accurately and account for treats in the daily caloric total. Dogs that maintain a healthy body weight live 5–10% longer than overweight dogs — a well-documented finding with meaningful real-world consequences. That's about two years of additional healthy life for a dog that might otherwise live to 14.

Frequently Asked Questions

Can dogs digest carbohydrates?

Yes. Dogs have 4 to 30 copies of the amylase gene (AMY2B) compared to wolves' 2 — an average sevenfold expansion that is associated with substantially higher amylase activity and greater starch-digesting capacity. This genetic adaptation occurred during domestication and is present across all breeds of domestic dogs. Dogs also have selective genetic changes in the enzymes responsible for converting starch to glucose (MGAM) and absorbing it through the intestinal wall (SGLT1).

Are grains bad for dogs?

No — there is no peer-reviewed evidence that grains are harmful to dogs or that grain-free diets are healthier. Whole grains are a source of fiber, B vitamins, minerals, and prebiotic compounds that support gut health. The grain-free trend was driven by human paleo and ancestral eating movements rather than veterinary nutrition science. In fact, the FDA has been investigating a potential link between grain-free diets and dilated cardiomyopathy (DCM) since 2018, though causation has not been confirmed.

Do dogs need carbohydrates in their diet?

Carbohydrates are not classified as an essential nutrient for dogs by AAFCO, meaning dogs can survive without them by synthesizing glucose from protein. However, carbohydrates are an efficient and well-tolerated energy source that dogs are biologically adapted to use — and complex carbohydrates from whole food sources provide additional nutritional value beyond just energy, including fiber, micronutrients, and functional compounds.

Why do some dog foods have so many carbohydrates?

Most dry dog foods are predominantly carbohydrate-based by caloric content, reflecting both the efficiency of plant-based energy sources and the economics of pet food production. This is not inherently problematic — as long as the formula is AAFCO-complete, protein minimums are met, and the carbohydrate sources are high quality. The issue is not the presence of carbohydrates but the source: whole food complex carbohydrates from oats, barley, and chickpeas are nutritionally different from refined starches, even at similar caloric content.

Can carbohydrates cause weight gain in dogs?

Carbohydrates can contribute to caloric excess, but they are not uniquely responsible for weight gain — any macronutrient consumed in excess of energy needs leads to weight gain. The primary driver of canine obesity is overall caloric intake relative to activity level, not the macronutrient composition of the diet. The most effective weight management tool for dogs is measured portion control, not macronutrient restriction.