Vet Student Study: Effects of Grains and Protein Levels in Dog Foods

Should grains be included in a dog's diet? How much protein is ideal? In her 2014 study, Kristyn Souliere of the University of Maine compares various commercial dog foods to identify the optimal nutritional balance for adult dog health and maintenance.

First, some background on dogs... 

"The dog is a subspecies of the grey wolf as Canis lupus familiaris, and classified in the order as Carnivora," says Souliere. "Despite public belief, the dog is in fact not a true carnivore; the dog is an indifferent omnivore. This means that dogs have carnivorous traits with sharp teeth and meat drive, but also have the omnivore digestive traits with an ability to break down carbohydrate feeds."

She points to trends in processed dog foods, including increased disease rates over the past 50 years, prevalent recalls, and the rise of grain-free diets, which coincide as the pet food industry shifts farther towards cheap, processed meat.

Effects on the Kidneys

"[The kidneys] can be affected by high protein with a low or a grain-free diet, which can cause azotemia (elevation of nitrogen-containing compounds in the blood) or uremia (inability of the kidneys to remove wastes from the blood)," says Souliere. She compares brands like Holistic Blend, containing 42% protein, and Natural Balance, containing 24% protein, to demonstrate that a protein level higher than that required for maintenance is potentially quite harmful. To provide a lower protein content, she concludes, healthy grains should be included in the diet for optimal kidney health.

Digestibility and Usage of Grains

Due to the presence of amylase, an enzyme produced in the pancreas to digest starch in the small intestine, dogs are able to utilize grains effectively as an energy source. "[Grains have] been shown to have many beneficial effects on the gastrointestinal system, especially improving the gastrointestinal health of dogs that have kidney disease. Studies have shown that adding grain into the diet will cause more successful utilization of blood urea as a source of nitrogen for microbial growth in the colon."

Learn More!

What Does Science Say About Grains for Dogs?

Ask the Vegan Vet: Starches and Grain-Free Diets for Dogs

Dogs are Not Wolves: Amylase, Starch Digestion and Vegan Diets


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Source: "A Study of the Nutritional Effect of Grains in the Diet of a Dog"

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