Grain-free Pet Diets: Are They Safe to Feed My Pet?

Grain-free Pet Diets: Are They Safe to Feed My Pet?

by Dr Gretta Howard, Senior Veterinarian

 

The trend of feeding grain-free diets gained popularity alongside the increase in gluten-free, paleo and ancestral diets in human nutrition. As a result, over the past 15 years or so there has been an increase in grain-free diets on the market available for pet owners to purchase. This has largely been marketed as ‘healthier’ for pets, advocating a reduced incidence of obesity, inflammation and adverse food reactions, which may contribute to skin or gastrointestinal issues.

But is this really the case? Let’s take a look.

Grain-free diets first became a popular diet with people looking to improve their overall health, but the majority of medical practitioners do not support eliminating whole grains from your diet. In fact, whole grains can be a rich source of nutrients, dietary fibre, anti-oxidants and phytochemicals, which may actually have an anti-inflammatory effect and reduce the risk of chronic disease, not increase it!

Unfortunately, the media tends to over-hype certain food groups or ingredients depending on the latest trend, and in the past, gluten and dairy have been targeted as unhealthy, but in recent times, especially with keto and paleo diets becoming more popular, grains have been overly blamed as a cause of health ailments.

Due to their increased popularity amongst humans, grain-free food entered the pet food market and became popular with pet owners, who assumed they were doing the right thing because it was misconceived as a healthier option for their pet.

The truth is that while in humans, there is a small percentage of people with chronic inflammatory disorders, such as irritable bowel syndrome (IBS) or rheumatoid arthritis (RA), that may benefit from grain-free diets and are directed to trial a grain-free diet by their doctor, the incidence of intolerance to grains such as rice, corn, wheat and oats in pets is extremely rare.

 

What is a grain-free diet for pets?

Traditionally, commercial pet foods have usually included grains. Also known as cereals, grains are the harvested seeds of grasses grown for food such as wheat, oats, rice and corn. Other examples of grains include sorghum, millet, rye and barley.

A grain-free diet for pets excludes all grains from the ingredients, often replacing these with other sources of carbohydrates including potatoes, peas, lentils or legumes (legumes are the fruit of plants in the pea family).

There was an exponential growth in grain-free diets entering the pet food industry between 2006-2016 due to market demand extrapolated from the human food industry.

 

What about gluten-free diets for pets?

Gluten is the protein in grain that remains after the starch has been removed. In people, coeliac disease can cause serious gastrointestinal reactions due to an intolerance to gluten and is diagnosed via blood test (AGA serology) that looks for anti-gliadin antibodies (gliadin is a component of the protein found in gluten). Whilst it is possible for coeliac disease to occur in dogs as well as humans, the incidence is exceedingly rare, with some inherited cases reported overseas in some lines of Irish Setters and Border Terriers. There has not been a proven case in cats yet. So, unless your pet has a proven sensitivity to gluten, there is no benefit in avoiding it.

 

Are grains or gluten a common cause of adverse food reactions in pets?

Food is often unjustly blamed for all sorts of health conditions in pets from itchy ears to paw licking. Whilst food intolerances can contribute to diarrhoea, grains or gluten are rarely the issue.

Furthermore, research has shown that the most common causes of adverse food reactions are chicken and beef. This is because these are the most common protein sources in pet foods, so more pets have been reported to react to them.

For cases of chronic diarrhoea, approximately 50% are related to a dietary intolerance, so a food elimination diet trial is worthwhile in these cases, once infectious and parasitic causes are ruled out. When choosing an appropriate diet to trial for these cases, grain-free or gluten-free diets are not on my radar, but rather choosing either a novel protein diet or a hydrolysed protein diet. A novel protein diet means feeding a protein your pet has not eaten previously, whereas a hydrolysed protein diet means feeding a specially formulated diet where the proteins have been altered to a size so small that the body does not recognise them as proteins anymore.

A genuine food allergy in pets causing skin issues is actually quite uncommon, with the vast majority of allergic skin disease being due to a reaction to environmental allergens, such as pollen, dust mites or mould spores, in combination with a leaky skin barrier, which often has a genetic basis.

 

Are there any health benefits in feeding a grain-free diet to my pet?

There is no proof that a grain-free diet is a healthier option for our pets. The fact is that grains rarely contribute to health problems in dogs and cats and are an important source of nutrients for our pets because grains contain valuable nutrients that are highly digestible.

Recently I’ve noticed an escalation in internet and social media video feeds trying to blame multiple health issues on the pet’s diet, to which there is no scientific basis. This has led to the myth that grain-free is better. These are usually advertisements aiming to sell a new diet or supplement claiming to fix these health issues – in short, they are marketing false information, misleading pet owners and are a scam.

In the majority of pets, there is no health benefit of feeding grain-free diets, although some veterinary therapeutic or prescription diets may be recommended to diagnose and treat food-induced allergies or dietary intolerance.  These are chosen because the ingredients are novel for that specific patient, not because they lack grains.

 

Is it safe to feed a grain-free diet to my pet?

Some dogs on grain-free or high legume diets (peas, chickpeas and lentils listed in the first five ingredients) have developed dilated cardiomyopathy (a type of heart disease). As such, we generally recommend against feeding these types of diets exclusively for extended periods unless required for a proven sensitivity to grain.

Most of the diets associated with reports of nutritional DCM have pulses (the edible seed inside the pod of a legume plant), such as peas and lentils, high in their ingredient lists. However, for many years, legumes and pulses have been used in various pet food brands with no evidence to indicate  they are inherently dangerous in smaller amounts.

 

Are all grain-free or diets with limited ingredients implicated?

There are some situations where your veterinarian may recommend a food elimination diet trial using a novel protein (one that your pet has not previously consumed) and these may or may not be grain-free, but generally are only used for a diagnostic trial for around 3-12 weeks, so a relatively short period, which is not considered to be harmful.

Some diets require long term feeding of diets with limited ingredients. Such diets may include a limited number of uncommon ingredients such as salmon, kangaroo, crocodile or potatoes. At this point, no therapeutic or prescription diets manufactured by major pet food companies (Hills, Royal Canin, Purina, Advance) have been associated with cases of diet-induced DCM.

 

What is dilated cardiomyopathy (DCM)?

Dilated cardiomyopathy is a serious heart condition where the heart’s ability to pump properly is compromised due to excessive heart chamber dilation and thinning of the heart’s muscle walls. Eventually, congestive heart failure develops, where there is a life-threatening buildup of fluid in the lungs and/or abdomen. The disease usually has a genetic basis and is seen most commonly in large and giant dog breeds such as Dobermans, Great Danes and Irish Wolfhounds, but can be seen in other breeds. Until recently, DCM was generally not seen in smaller dog breeds, until the link between feeding grain-free diets and heart disease was identified.

Signs of DCM in dogs include:

• Weakness
• Lethargy
• Exercise intolerance
• Coughing
• Fainting

 

If any of these signs are noticed, an urgent veterinary consultation should be booked in so that your vet can check your dog’s heart. Diagnosis is usually via radiographs (chest x-rays) and echocardiogram (heart ultrasound).

 

What is the cause of heart problems in pets fed grain-free diets?

Veterinary cardiologists started noticing there was an increase in unexpected dog breeds developing serious heart disease due to DCM, many of whom were on grain-free diets. A full investigation was launched in the USA in 2018, and reporting of atypical cases to of heart disease and their diet history to the Food and Drug Administration (FDA) was encouraged. Over 1300 cases were reported over 5 years within the USA alone. Many of the cases reported were small breeds, which are not the classical presentation seen for inherited DCM.

The most common factor between these cases was dogs eating diets with peas and lentils high on the ingredient list, which tend to disproportionately be grain-free diets, though not ALL grain-free diets were associated with cases of heart disease.

Interestingly, veterinary cardiologists have hypothesised that it is not the absence of grains but the presence of pulse legumes, which is basically the seed of legume plants, such as peas, lentils, chickpeas, fava beans, that is associated with diet-induced DCM. The precise mechanism by which these diets lead to atypical DCM remains unclear and it is not known whether it is the pulse legumes are directly cardiotoxic or if they interfere with nutrient absorption of other important cardiac protectants.

 

Is grain-free diet-related heart disease reversible?

Many affected dogs show clinical and functional improvement with appropriate diet changes and prescription medication, suggesting that diet-induced DCM can be reversible, which is not the case in inherited DCM, which generally carries a poor prognosis. So provided the link between diet and DCM is identified and corrected, the prognosis for these atypical nutritional cases of DCM is much better. However, dogs that present in congestive heart failure have a worse prognosis, because the dietary change may not have a chance to take effect when in advanced stages of heart disease.

 

Is dietary taurine-deficiency to blame?

The reported cases of diet-induced DCM were not linked to taurine insufficiency in the cohort that were tested. Blood assays of taurine in affected dogs showed normal levels.

Taurine deficiency is however linked to heart disease in Golden Retrievers, with well-documented cases of taurine-deficiency-related DCM in this breed. Other breeds reported with taurine deficiency include Dalmatians, American Cocker Spaniels and Newfoundlands.

In cats, taurine-deficiency has long been a known factor in the development of DCM, particularly those fed a diet for dogs, or those on an unbalanced limited ingredient, all meat or vegetarian diet for long periods of time. Just like humans cannot produce Vitamin C, cats cannot make their own taurine and must ingest it.

 

How do I determine if my pet’s diet is a diet of concern?

There is currently no AAFCO (Association of American Feed Control Officials) or PFIAA (Pet Food Industry Association of Australia) requirement to advise pet owners on the pet food label that a particular diet is grain-free or grain-inclusive, so you need to actually read the ingredients list to determine whether a particular pet food is a diet of concern or not. Legume and pulse ingredients should be listed after the meat and grains, and pet food diets should preferably contain two or less of the suspect ingredients. If peas or lentils are the main carbohydrate source and listed in the first five ingredients, then consider changing to a diet that contains grains.

Making safe and balanced pet food is not simple, requiring a team of professionally trained scientists, including veterinarians that specialise in nutrition, as well as significant research and extensive testing to ensure quality control is maintained. Not all pet food companies do this.

Advertisements and websites for pet foods should not contain unverifiable claims, perpetuate nutrition myths or promote products solely by criticising other manufacturers’ products.

 

What about cats fed grain-free diets?

To date there has not been any confirmed cases of grain-free diets causing heart issues in cats, unless the diet was also deficient in taurine (a known cause of DCM in cats). Cats are obligate carnivores, so legumes and pulses are generally not included in diets formulated for this species.

 

Conclusion

Research into the field of nutrition-induced heart disease continues to emerge as further studies are published. Veterinary cardiologists, veterinary nutritionists and research scientists are working together to better understand, educate, and prevent nutritional causes of heart disease in pets.

 

Sources

Zhang J, Ji Y, Yang Y et al (2025) Grain-Free Diets for Dogs and Cats: An Updated Review Focusing on Nutritional Effects and Health Considerations. Animals. 15(14).

Mornard L, Brasileiro A, Santos M (2025) Role of Diet as a Predisposing Factor for Dilated Cardiomyopathy in Dogs: A Narrative Review. Vet Sci. 12(11).

Freeman L, Rush J, Berridge B (2025) Dogs with diet-associated dilated cardiomyopathy have higher urine di-docosahexaenoyl (22:6)-bis(monoacylglycerol)phosphate, a biomarker of phospholipidosis. Am J Vet Res. 86(1).

Rishniw M, Pion P, Valeika S (2023) Diet-associated dilated cardiomyopathy – The issue remains unresolved. J Nutr. 153(11):3341-3342.

Owens E, Leblanc N, Freeman L et al (2023) Comparison of echocardiographic measurements and cardiac biomarkers in healthy dogs eating nontraditional or traditional diets. J Vet Intern Med. 37(1):37-46.

Milesi G, Rangan A, Grafenauer S (2022) Whole grain consumption and inflammatory markers: A systemic literature review of randomized control trials. Nutrients. 14(2): 374. Published online. Christopher M, Casas R (Academic Editors).

Freeman L, Rush J, Adin D, et al. (2022) Prospective study of dilated cardiomyopathy in dogs eating nontraditional or traditional diets and in dogs with subclinical cardiac abnormalities. J Vet Intern Med. 36(2):451-463.

US Food and Drug Administration Questions & Answers: FDA’s Work on Potential Causes of Non-Hereditary DCM in Dogs

Tufts University PetFoodology A broken heart: Risk of heart disease in boutique or grain-free diets and exotic ingredients

UC Davis Weill School of Veterinary Medicine UC Davis Investigates Link Between Dog Diets and Deadly Heart Disease

UC Davius Weill School of Veterinary Medicine Update from Nutrition Services on Concern Between Diets and DCM in Dogs

Eating Well Is a Grain-Free Diet Healthy? Here’s What Dietitians Say

All Trades DVM Diet-Associated Non-Hereditary DCM

Veterinary Partner Article Diets and Heart Disease in Dogs and Cats

Diet-Associated DCM Education Alliance – Facebook Group