Are grains unhealthy for pets?

Just because some foods could be considered ‘unhealthy’ to humans, does that necessarily mean the same for our pets? Dr Delisa Appleton explains.

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Grain-free diets are one of the largest growing segments of the pet food market. More and more pet owners are turning to these diets which are sometimes billed as “more natural” for pets, with fewer fillers, fewer carbs and less likely to cause allergies.

So, are grain-free diets indeed better for pets?  Before we come to any conclusion, let’s explore the science.^1,2,3

What is a filler?

A filler is considered an ingredient with little or no nutritional value. So, is it legitimate to label grains as a filler? No. Grains contribute valuable nutrients to the diet including vitamins, minerals, antioxidants, essential fatty acids and fibre, which are all essential for health.

Are grain-free diets more ‘natural’?

Domestic dogs today are vastly different phenotypically and biologically from their wolf ancestors. In fact, dogs and cats have evolved with humans in their ability to digest grains, as well as many other sources of carbohydrates. What’s more, grains used in pet foods undergo processing, like grinding, cooking and extrusion, making them highly digestible.⁶

It could be argued that substituting grains for highly refined starches like potatoes, sweet potatoes, tapioca (cassava), peas or lentils is no more ‘natural’ a diet for a wolf to consume. These foods may contain as much, sometimes more carbohydrates as a diet containing grains.  Additionally, these ingredients often provide fewer nutrients and less fibre than whole grains.

Are dogs carnivores?

Another confusion is that both wolves and dogs belong to the taxonomic Order Carnivora, which often gets confused with the thinking that dogs are carnivorous. While these animals all share a dental structure that originally evolved for shearing meat, most of the species in Carnivora are now omnivores (skunks, raccoons, bears, etc.) and a few are completely or almost completely herbivores like the Giant Panda, which only consumes bamboo.

Cats, on the other hand, are considered obligate carnivores, meaning they have a requirement for nutrients present only in animal tissue within their diet. That said, while cats do require part of their protein to come from animals, their systems are also very good at digesting and absorbing nutrients from high-quality, plant-based ingredients.⁷

What about food allergies and sensitivities?

While food allergies in pets are uncommon (they account for one per cent of skin diseases or less than 10 per cent of allergic skin disease in dogs ⁸), allergies to grains are even rarer. That’s because allergies are abnormal or inappropriate reactions of the immune system against a normal protein. They can form to any protein or protein-containing food or ingredient. However, the small numbers of pets that do have allergies are most likely to be allergic to animal proteins. In dogs, the most commonly reported food allergens are beef, dairy and chicken. In cats, it’s beef, dairy and fish.^8,9  This reflects just how commonly used these ingredients are in commercial diets, rather than an increased tendency to cause allergies.

As some grains like wheat contain protein, allergies can occur. However, reactions to other grains and carbohydrate sources like rice, corn, and potato are very uncommon. If a dog or cat has a diagnosed food allergy, treatment involves feeding either a hydrolysed diet or a food containing a single protein and carbohydrate source which they have not been previously exposed to. These are called novel protein and carbohydrate diets. Take care when choosing a food claiming to be hypoallergenic or novel. While they may only have one protein and carbohydrate source mentioned on the front of the pack, on closer examination of the ingredient list you may find several other sources of both.

Some pet owners cite the potential for gluten sensitivity as the reason for avoiding grains in their pet’s food. Celiac disease in humans is a heritable autoimmune disease associated with hypersensitivity to gluten proteins in wheat and other related grains such as barley and rye. Corn gluten and rice gluten, on the other hand, are quite different from wheat gluten and can be consumed by most celiac patients without concern. Gluten intolerance is also exceedingly rare in pets, with gastrointestinal signs from consuming gluten having only been observed in a small number of dogs, including some Irish Setters.

So, are grains unhealthy for pets?

The answer is no. There is no evidence that grains are nutritionally harmful to pets. There are many good quality commercial pet foods available both with and without grains.

The most important things to look for in a food is if it provides high-quality, highly digestible, complete and balanced nutrition that is formulated for the correct life-stage. For example, if a food is formulated for ‘growth and maintenance’ or for ‘all life stages’, it means that the food must meet the nutrient requirements for the most demanding life stage, a growing puppy or kitten. Be sure to select a diet that is formulated specifically for the life stage of your pet, such as puppy/kitten, adult or mature

It’s also important to remember that ingredients are included in pet foods primarily as a source of nutrients. Animals require specific nutrients such as amino acids from protein and glucose from carbohydrate, not specific ingredients.

Finally, you should consider the longevity and history of the manufacturing company, their commitment to continual research and development, along with the approachability and ethical culture of the company when deciding to feed a particular food,  not just whether the food contains grains or not.

Resources

1. http://vetnutrition.tufts.edu/2016/06/grain-free-diets-big-on-marketing-small-on-truth/
2. http://petnutritionalliance.org/site/pnatool/are-grains-unhealthy-for-dogs-and-cats-2/
3. Laflamme D, Izquierdo O, Eirmann L, Binder S. Myths and misperceptions about ingredients used in commercial pet foods. Vet Clin North Am Small Anim Pract. 2014;44:689-698.
4. Ovodov, N. D. et al. A 33,000-year-old incipient dog from the Altai mountains of Siberia: evidence of the earliest domestication disrupted by the last glacial maximum. PLoS ONE 6, e22821 (2011)
5. Davis, S. J. M. & Valla, F. R. Evidence for domestication of the dog 12,000 years ago in the Natufian of Israel. Nature 276, 608–610 (1978)
6. Murray SM, Fahey GC, Merchen RN, et al. Evaluation of selected high-starch flours as ingredients in canine diets. J Anim Sci 1999; 77:2180-2186.
7. https://www.hillspet.com/cat-care/nutrition-feeding/what-is-grain-free-cat-food
8. Verlinden A, Hesta M, Millet S et al. Food allergy in dogs and cats: a review. Crit Rev Food Sci Nutr 2006;46:268
9. Roudebush P. Ingredients and foods associated with adverse reactions in dogs and cats. Vet Dermatol 2013; 24: 292-294

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