Are grain-free diets dangerous for pets?
are grain-free diets really good for dogs?
Is grain-free pet food dangerous for our pets?

Plenty of premium dog food brands have created lines of grain-free diets for the health-conscious pet parent. As our dogs and cats increasingly become our family members, we find ourselves spending more on their well-being than ever before.

Unfortunately, this often leaves us confused and vulnerable to conflicting information about which diet is best for them.

However, confusion over what to feed our dogs isn't all our fault. Just like with us, trending "fad" diets and flashy branding promise our pets optimal health. And with the eye-watering price tags attached, we often assume we'll get what we pay for.

One of the newer trends is grain-free pet food. Grain-free dog and cat food are marketed as a more "natural" way of feeding dogs and cats by getting back to their ancestral carnivore roots.

Its claims are similar to those made by the gluten-free and paleo diets for humans.

But are grain-free diets genuinely healthier for our pets? Or are they just a marketing tool? Worse yet, are grain-free diets dangerous for pets, particularly dogs?


What is a grain-free diet, and what can dogs and cats eat on it?

The positives of a grain-free diet: should you feed dogs grain-free food?

More Mycotoxins are found in food with grain than without

Some dog breeds may have a very rare gluten intolerance

Allergies to grains

Is a grain-free diet bad for dogs? The dangers of a grain-free diet

Grain-free diets have been linked to increased rates of heart disease in dogs

Grain-free can mean replacing necessary animal proteins with cheaper plant-based proteins

So do grain-free diets cause heart disease in dogs?

Is the grain-free diet bad for cats?

Key takeaways

What is a grain-free diet, and what can dogs and cats eat on it?

A grain-free diet is a pet food marketing tool where all grains, both gluten and non-gluten-free, are removed. This includes corn, wheat, oats, barley, and rice. To replace the carbohydrate and starch sources in pet food, flours made from legumes, such as peas or lentils, or potatoes are used instead.

The trends in pet food tend to follow trends in human diets.

Demands for higher protein diets in the pet industry followed our own bandwagon of paleo diets. Grain-free quickly followed as any source of gluten became seen as an allergen or source of inflammation.

Furthermore, as we began to demand a greater variety of "boutique" or "exotic" foods in our animals' diets, the pet industry was equally quick to cater to this. Unfortunately, this happened without enough research to tell exactly how this would impact our dogs and cats' health.

While starch and carbohydrates are problematic in pet food, this is due mainly to the increasing body of evidence against highly processed dog food. Meanwhile, the marketing gimmick and dog food craze of "grain-free" may come with its own serious health problems.

But before we get into that, let's look at whether there are any benefits of grain-free pet food.

The positives of a grain-free diet: should you feed dogs grain-free food?

a dog may enjoy some health benefits from a grain-free diet
Why might you consider a grain-free diet for your dog?

While the debates surrounding what we should feed our pets are heating up, there are definitely some studies that should be taken into account in favor of grain-free diets. Among their findings are:

1. More Mycotoxins are found in food with grain than without

Mycotoxins are secondary fungal metabolites that are known to cause chronic diseases in both animals and people.

One study found significant concentrations of mycotoxins in pet food that contained grains, particularly dry dog food. However, it did not find it in grain-free pet foods.

Interestingly, this study did not recommend removing grains from pet food. Instead, it suggested that manufacturers use grains categorized as US No. 1 by the USDA instead. This simply means high-quality grains rather than low-quality grains.

The USDA grades grains according to how fit they are for human consumption, so the type of grain is not as important as the quality. Low-quality grains may have more damaged or broken kernels, have a strange odor, or have heat damage. All of this could contribute to the growth of mold and mycotoxins if the pet food manufacturer uses grains not fit for human consumption. So pet owners should note the grade of grains on the back of the ingredients list.

2. Some dog breeds may have a very rare gluten intolerance

Gluten intolerance in dogs is extremely rare, and it is not the primary reason that grain-free diets exist. However, certain breeds are susceptible to different kinds of gluten sensitivity.

To date, we only know of this affecting some bloodlines of setters, Soft-Coated Wheaten Terriers, and the Border Terrier. Suppose you have one of these breeds and suspect gluten sensitivity. In that case, it's best to have a vet test your dog or to ask for DNA testing before deciding on a dietary solution.

3. Allergies to grains

Allergies to grains do exist in our pets. However, it is not as common as we think. Only about 10% of allergies in our pets are believed to come from grains. To put that into context, only about 0.2% of dogs and 0.1% of cats actually have food allergies.

If you suspect a food allergy in your dog, your vet can try intradermal skin testing or RAST testing to isolate the allergen.

The most common food allergies in pets come from dairy, chicken, beef, and other animal protein sources. So if you suspect that your dog has a nutritional allergy, one can use DNA testing to isolate the source of the allergy rather than to automatically blame grains.

This leads us to the next point, are grain-free diets actually dangerous for our pets?

Is a grain-free diet bad for dogs? The dangers of a grain-free diet

At best, grain-free diets were largely dismissed as a marketing and branding tool by pet manufactures. However, a recent investigation by the FDA and subsequent studies have alarm bells ringing.

Since we all want what's best for our pets, we will give a quick overview of what you need to know, particularly if you are a dog owner.

1. Grain-free diets have been linked to increased rates of heart disease in dogs

The FDA investigation centers on the increased reports of canine dilated cardiomyopathy (DCM). Their initial studies showed that of the dogs reported, most were on a grain-free diet.

They listed the most common brands of food given to the dogs affected.

DCM is a condition where the heart becomes enlarged and the heart muscles weaken. It is potentially life-threatening.

However, it should be noted that some in the pet food industry hit back against the FDA's warning, citing a lack of transparency and a skewed methodology.

They also pointed out that the FDA seemed to be zoning on the dog foods' grain-free aspect rather than the many possible causes. This includes the processing involved in dry pet food or the higher fiber content in pea and legume-based foods, which can interfere with a dog's ability to absorb taurine.

The important thing to remember is that the link between grain-free and DCM still needs further research. In the meantime, pet owners should remember that grains aren’t dietary boogeymen and replacing them with new, more expensive ingredients may cause more harm than good.

2. Grain-free can mean replacing necessary animal proteins with cheaper plant-based proteins

When it comes to taurine absorption—a vital amino acid for dogs and cats—grain-free diets may create more of a problem.

To replace the starch-binding agent that grains provide, grain-free food typically uses high quantities of flour from peas, lentils, or potatoes.

In fact, in the dog food tested by the FDA, over 93 % of the grain-free diets contained legumes like peas or lentils.

Legumes are extremely high in protein. This allows manufacturers to cut down on expensive animal proteins and rely on the proteins that come from the peas or lentils instead. Since these proteins don't have taurine as the animal proteins do, they may create a deficiency that contributes to the high cases of DCM.

So do grain-free diets cause heart disease in dogs?

Grain-free diets are recent health trend for both dogs and cats
Does grain-free pet food give our pets heart disease?

Unfortunately, the science isn't as straightforward as we would like at the moment.

In general, most of the experts blame "boutique" dog foods for increasing the number of exotic ingredients in food to increase prices, but not necessarily the pet's health.

One study on Golden Retrievers found those pet foods containing legumes, such as peas or lentils, or potato flour as the main ingredients are linked to increased heart size and weakened cardiac muscles.

However, the most common culprit is in breeds with a genetic predisposition to DCM, such as the Great Dane, Boxer, Cocker Spaniel, and Doberman Pinschers.

Another study concludes that the causes of DCM are multi-faceted but likely have much to do with taurine and whether it is bioavailable. Factors that may influence this include:

  • Low-protein or high-fat foods
  • The effect of legumes on the microbiome of the colon, leading to taurine not being absorbed
  • The replacement of animal protein with taurine-free plant-based protein.

Dr. Lisa Freeman is careful to add the following points to the argument:

  • The main culprit is not only grain-free diets but what she labels as "BEG" diets. That is, boutique pet foods, exotic ingredients, or grain-free diets may introduce elements into pet foods that have an unknown impact on overall nutrition.
  • Low-taurine levels are actually not found in most cases of DCM. This suggests that something other than taurine may be involved.

Is the grain-free diet bad for cats?

So far, most of our focus has been on the effect of grain-free diets on canines. But what about our feline loved ones?

Taurine plays an even more significant role in cat nutrition than it does in dogs, and a shortage of it in cat food led to major health problems in the 70s. However, there are other reasons to reconsider a grain-free diet for your cat.

Dr. Lynne Buzhardt points out that there is no science that grains are essentially harmful to cats. A study in the Journal of Feline Medicine and Surgery recently made the following discoveries:

  • Labels can be misleading. Of the grain-free cat foods tested, one actually contained grains.
  • Both grain-free and non-grain-free diets had about the same calories. Keep in mind that most studies on animals show a high-nutrition, low-calorie diet as being the best for health longevity.
  • Some grain-free diets had similar amounts of carbohydrates to non-grain-free diets. Some even had more carbs!
  • Some of the diets contained odd ingredients with no known benefits for cats, such as lettuce, celery, avocado, and chia.

Many grain-free cat foods also contained exotic ingredients such as venison, rabbit, and bison. So it is fair to say that grain-free diets for cats might well fall into the same "BEG" category of expensive foods that do not necessarily have any extra nutritional benefits.

Key takeaways

It's not definitive that grain-free diets cause DCM in either dogs or cats. Nevertheless, there is some evidence to suggest that it might be problematic.

As a pet owner, if you feel your dog has an allergy that needs a grain-free diet, it's best to first have your pet tested. After that, you can make decisions based on your dog or cat's specific medical needs.

In general, it may be best not to be duped by overpriced and over-processed pet foods promising good health. Rather, consider the two metrics needed for deciding on the best food for your pet.

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