Now, for something completely different, the Skeptical Raptor is giving way to the Skeptical Canine (not really) to discuss grain-free dog food fad. It is based on pseudoscience and harms our pet dogs. I wish humans would keep their nutrition nonsense away from their pets, as the new fad of giving cats only vegan food. So, this article is here to give you some science about dog food.
I have no idea where this grain-free dog food fad began, but we can assume it started like all other human food crazes with about 1% science and 99% myth, misinformation, pseudoscience, and outright lies from those who want to profit from it. Wait, that sounds like cancer cure and anti-vaccine scam artists.
Anyway, the Skeptical Canine is here to talk about grain-free dog food, and whether it’s healthy for dogs. Well, I hate giving away the plot, but no, it’s not. We’ll try to explain why.
The evolution of dogs
It’s possible that this grain-free dog food obsession started from a misunderstanding of how domestic dogs evolved. We seem to think that dogs are just wolves. That’s only partly true.
According to modern research, dogs and an extinct Late Pleistocene wolf diverged about as recently as 10-15 thousand years ago, although there is some evidence that dogs were domesticated up to 40 thousand years ago. That extinct wolf evolved into domesticated dogs, the modern grey wolf, and some related taxa, such as jackals and coyotes.
They are all in the same genus, Canis. The grey wolf and domestic dog are genetically similar because of cross-breeding, either accidentally or intentionally.
Domesticated dogs co-evolved with modern humans, as humans moved from a hunter-gatherer society to agricultural. This is important because domesticated dogs eventually evolved to eat human foods. Yes, the domestic dog has different dietary needs than their ancestors.
The gene, AMY2B (Alpha-Amylase 2B), codes a protein that assists with the first step in the digestion of dietary carbohydrates. Wolves have only two copies of that gene, whereas dogs have substantially more copies of the gene. This gives domestic dogs a better ability to exploit carbohydrate-rich diets as they fed on agricultural products and waste in early human history.
In fact, the Saluki dog breed, which originated in the Fertile Crescent, where agriculture started, has 29 copies of the gene. On the other hand, Arctic dog breeds, such as the American and Siberian husky, had more carnivorous diets and lack the high number of the AMY2B gene.
Furthermore, an analysis of the dog versus the wolf genome shows that the dog has more genes to process lipids, probably as a result of early human hunter-gatherers leaving lots of meat scraps. The dog diet, and its ability to metabolize it evolved as human food supplies changed over thousands of years.
However, there are some anomalies in the research on the genetics of dogs and wolves. A genetic examination of dog remains found in Germany from about 4,700 to 7,000 years before present show no increase in the number of copies of the AMY2B gene despite the fact that agriculture had arisen in this area at that time period. However, most of the evidence supports the high level of AMY2B genes in most modern dog breeds compared to wolves.
The point of this exercise in the evolution of dog metabolism is important – most domestic dog breeds have evolved to consume human food, far different than what an undomesticated wolf would encounter in the wild 10,000 years ago. The point is that domestic dogs are not true carnivores, but are, in fact on the somewhat carnivore side of a true omnivore.
Thus, our story now circles back to grain-free dog food.
Grain-free dog food – healthy or not?
We have seen that dogs have, more or less, evolved to consume human food. So, what happens if we try to force our dogs to become wolves again? Nothing good, and that’s why we need to look at whether grain-free dog food is a good thing for our pets.
One health issue has been correlated (and is probably causal) with eating so-called “BEG” diets (boutique, exotic, grain-free) which are, obviously grain-free, but also include exotic components like kangaroo and other foods that are unknown to dogs. This diet results in a condition called dilated cardiomyopathy, which can be deadly to a dog (and to a human, since the condition is known to many mammals).
Dilated cardiomyopathy, or DCM, (the link is to the human disease, but the signs, symptoms, and pathophysiology are the same in dogs) is a condition in which the heart becomes enlarged and cannot pump blood effectively. According to an article from the Clinical Nutrition Service of Tufts University Cummings Veterinary Center:
DCM is a serious disease of the heart muscle which causes the heart to beat more weakly and to enlarge. DCM can result in abnormal heart rhythms, congestive heart failure (a build-up of fluid in the lungs or abdomen), or sudden death. In dogs, it typically occurs in large- and giant-breeds, such as Doberman pinschers, Boxers, Irish Wolfhounds, and Great Danes, where it is thought to have a genetic component. Recently, some veterinary cardiologists have been reporting increased rates of DCM in dogs – in both the typical breeds and in breeds not usually associated with DCM, such as Miniature Schnauzers or French Bulldogs. There is suspicion that the disease is associated with eating boutique or grain-free diets, with some of the dogs improving when their diets are changed.
So, is this latest rash of DCM caused by taurine deficiency? Most of these affected dogs were eating boutique, grain-free, or exotic ingredient diets. Some of the dogs had low taurine levels and improved with taurine supplementation. But even some of those dogs that were not taurine deficient improved with taurine supplementation and diet change. Fortunately, cardiologists reported the issue to the FDA which is currently investigating this issue.
Taurine deficiency, which is caused by the lack of this important amino acid in the diet of domesticated dogs and cats, has been an issue that’s been known for nearly 40 years. Many cat and dog foods are fortified with taurine, which is readily available in the diet of wild felines and canines.
However, grain-free foods are not an underlying cause of taurine deficiency – there appears to be something else that causes DCM. It’s biologically plausible that there is something in grains that domestic dogs can metabolize, because of the presence of the AMY2B gene, which helps prevent DCM.
Let’s take a look at this from another perspective. Why do pet owners feed their dogs a grain-free diet? Well, not for very good reasons, again according to the Clinical Nutrition Service:
Many pet owners have, unfortunately, also bought into the grain-free myth. The fact is that food allergies are very uncommon, so there’s no benefit of feeding pet foods containing exotic ingredients. And while grains have been accused on the internet of causing nearly every disease known to dogs, grains do not contribute to any health problems and are used in pet food as a nutritious source of protein, vitamins, and minerals.
Furthermore, the ingredients in some of these BEG dog foods are not well-controlled and vary all over the place. Again, according to the veterinarians at Tufts University:
Making high quality, nutritious pet food is not easy! It’s more than using a bunch of tasty-sounding ingredients. The right nutrients in the right proportions have to be in the diet, the effects of processing (or not processing) the food need to be considered, and the effects of all the other ingredients in the food need to be addressed, in addition to ensuring rigorous quality control and extensive testing. Not every manufacturer can do this.
Although there needs to be much more investigation into this aspect of our pets’ diets, we know that grain-free dog food brings little-to-no benefit with an incredible risk of a deadly heart condition (see Note 1).
I hate food fads applied to our pets. Of course, I hate food fads for humans too (see gluten and ketogenic nonsense). In fact, many times humans want to confer their own food beliefs on dogs and cats. Don’t get me started on people trying to put their cats, an obligate carnivore, on a vegan diet.
So, let’s go through the scientific facts:
- Most domestic dog breeds co-evolved with humans moving from a hunter-gatherer to an agricultural society.
- As a result, most dogs evolved to better process the scraps of human society, including agricultural by-products and waste. Like bread.
- Grain-free dog food provides no clinical benefits to dogs – food allergies are extremely rare in dogs, especially, let me repeat myself, since dogs have genes that allow them to consume grains. And please stop with the “GMO” nonsense – GMO foods for dogs are as safe as they are for humans, meaning that they are safe (see Note 2).
- Grain-free dog food is linked to dilated cardiomyopathy, a deadly cardiovascular condition.
So what should you do about your dog’s diet? Well, let’s go back to the fine folks at the Clinical Nutrition Service at Tufts:
Reconsider your dog’s diet. If you’re feeding a boutique, grain-free, or exotic ingredient diets, I would reassess whether you could change to a diet with more typical ingredients made by a company with a long track record of producing good quality diets. And do yourself a favor – stop reading the ingredient list! Although this is the most common way owners select their pets’ food, it is the least reliable way to do so.
And be careful about currently available pet food rating websites that rank pet foods either on opinion or on based on myths and subjective information. It’s important to use more objective criteria (e.g., research, nutritional expertise, quality control in judging a pet food). The best way to select what is really the best food for your pet is to ensure the manufacturer has excellent nutritional expertise and rigorous quality control standards (see our “Questions you should be asking about your pet’s food” post).
In other words, don’t overthink your dog food. You’ll be doing your dog a favor.
- Because there will be new readers to this blog as a result of this article, I need to state something. Anecdotes and testimonies about grain-free dog food are totally irrelevant from a scientific perspective. Short of a published (in a highly respected peer-reviewed veterinary or biology journal) clinical trial (yes, pets are included in many clinical trials) that shows a statistically significant difference between dogs who receive a grain-free diet versus ones that don’t, we lack any evidence of the value of the diet. But we do have observations that there appears to be a causal link between the diet and cardiovascular issues for dogs. In the world of clinical cost versus benefit, the costs (or risks) far outweigh anecdotal benefits.
- Seriously, stop this anti-GMO inanity. We’ve been genetically altering foods for at least 10,000 years (along with our dogs, apparently), and humans are healthier today than ever. Well, partially thanks to vaccines, but that’s another story that I tell weekly.
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