Why my dogs do better on grain free (experience + physiology) 

​In my experience feeding and living with numerous Weimaraners over many years, the majority of my dogs have consistently done better on grain free diets. While dogs can digest carbohydrates, many individuals particularly high energy, athletic dogs, have a limited tolerance for chronic starch intake. When starch intake exceeds digestive enzyme capacity, undigested carbohydrates reach the colon, leading to fermentation, gas and loose stool. 

For my dogs, grain free diets paired with appropriate animal protein, fat and whole food additions result in better stool quality, digestion and overall condition. Grain tolerance varies widely, which is why I evaluate individual ingredients rather than labeling all diets, grain inclusive or grain free, as appropriate for every dog.

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The nutrition side (not the FDA side):

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Why legumes are avoided (grain free and grain inclusive) 

• Peas, lentils, chickpeas and garbanzo beans  

• May interfere with taurine metabolism and amino acid bioavailability 

• Often inflate protein percentages using plant protein 

• High fiber + resistant starch → reduced digestibility 

Why corn is limited 

• Lower protein digestibility than rice 

• High glycemic impact 

• Often displaces animal protein 

Why potatoes are limited 

• Very high starch 

• Low protein contribution 

• Often used heavily in grain-free formulas  

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Grain hierarchy

 Most digestible → least digestible 

• White rice 

• Rice flour 

• Oats 

• Brown rice 

• Barley 

• Corn 

• Wheat 

• Sorghum 

This hierarchy explains why chicken & rice works for GI upset and why many grain inclusive kibbles cause chronic diarrhea 

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The importance of grain digestibility is that it can reduce the overall digestibility and nutrient absorption of the meats/proteins. For example, let's use one of the leading sporting dog foods, the first few ingredients are beef, rice, by-product meal, and then corn meal and whole corn. While this may be a 30% protein label on the bag, that number reflects what's present in the food, not necessarily what your dog can efficiently digest and utilize. Diets with a high proportion of corn and less digestible carbs (aka fillers!) may result in a portion of the protein passing through the digestive tract less efficiently, reducing the amount of usable amino acids your dog is actually absorbing. Also think of it like a human eating a huge salad with mostly lettuce, while it technically has calories and nutrients, your body expends energy to digest and process it so the net gain is very low. Similarly, diets with a lot of fillers provide energy, but your dog may also expend significant energy digesting these ingredients, so even though that label says 30%, they may burn more calories trying to extract nutrients than they actually gain.

 

Why white rice is better than brown rice 

This is important and often misunderstood. 

White rice 

• Bran and germ removed 

• Lower fiber 

• Less phytic acid 

• Easier starch gelatinization 

• More digestible 

Brown rice 

• Retains bran layer 

• Higher insoluble fiber 

• More phytic acid (binds minerals) 

• Greater fermentation risk 

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While brown rice is often marketed as healthier, white rice is generally more digestible for dogs due to its lower fiber content and reduced fermentation risk. This is why white rice is commonly recommended during gastrointestinal upset. 

 

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Chicken & rice kibble context matters 

​A chicken and rice formula can be an acceptable alternative for owners who prefer not to feed grain free; however, when rice appears as the second ingredient, the overall starch load may still be excessive for some dogs. 

Even highly digestible grains can cause digestive issues when included in large amounts or fed chronically. 

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Dogs are facultative carnivores / scavenger omnivores, not true omnivores !!!!

They: 

• Can digest starch, but with limits 

• Rely primarily on: 

• Pancreatic amylase 

• Brush-border enzymes (maltase, sucrase) 

Dogs lack salivary amylase and rely on pancreatic secretion after food reaches the intestine. Fun fact, their teeth and jaws are designed primarily for tearing meat, they have prominent canines and limited side to side grinding motion, like herbivores such as a cow that rely on digestion starting in their mouths, dog's strong stomach acids do most of the breakdown which is why you often see dogs swallowing large chunks of food rather than chewing thoroughly.

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Why grain inclusive foods cause diarrhea in some dogs- in my personal experience it's often full blowout, not just soft

Enzyme capacity is finite 

Dogs can digest starch up to a threshold. 

When that threshold is exceeded: 

• Starch reaches the colon undigested 

• Colonic bacteria ferment it rapidly 

• → gas + osmotic diarrhea (“blowouts”)  

 

Grain type matters a LOT 

Not all grains are equal

Highly digestible  

• White rice 

• Well-cooked, low fiber 

• Rapid gastric emptying 

• Minimal fermentation 

This is why home cooked chicken & rice works during GI upset. 

 

Moderately digestible 

• Brown rice 

• Oats 

• Barley 

Higher fiber → slower digestion → more fermentation risk. 

 

Poorly tolerated (for many dogs) 

• Wheat 

• Corn 

• Sorghum 

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Higher insoluble fiber means harder protein matrix means more fermentation. 

These are the grains most commonly associated with: 

• Loose stool 

• Gas 

• Volume increase 

 

Why kibble rice ≠ cooked chicken & rice  

This is critical. 

Home cooked chicken & rice 

• Rice is: 

• Fully gelatinized 

• Simple matrix 

• Low inclusion rate relative to protein 

• Fed short term 

Kibble with rice as #2 

• Rice is: 

• Extruded (partially gelatinized) 

• Often combined with other starches 

• Fed chronically often crowds out protein 

So even though it’s “rice,” the load and context are totally different. 

 

 

  

 

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