There are those out there that advocate for or feed their dogs an all-meat diet. This breaks down into 2 main categories: Whole Prey Model, and Prey Model Raw (PMR). The PMR diet can also be broken down into 2 ratios. The first is 80% Muscle Meat 10% Edible Bones 10% Organs. The second is 80% Muscle Meat 10% Edible Bone 5% Liver 5% Other Organs
The argument is that dogs evolved from wolves and don’t need Carbs. There was actually an interesting study that came out a few years ago. They found a pack of wolves that ate a significant amount of blueberries. They even found wolves regurgitating blueberries for their pups.
While those who advocate for an all meat diet have the best intentions, it ultimately does our pets a great disservice.
Dogs are not Wolves
We do need to remember that our dogs are not wolves. Our dogs split from Wolves over ten thousand years ago. Our dogs have lived and evolved beside us for thousands of years. Eating first our garbage than our scraps, and as people realized dogs were great hunting partners, they probably even ate the same food sometimes. That means for thousands of years, our dogs ate whatever leftovers, or even the same food we did for a significant portion of their evolutionary history. Their diet, like our diet, changed with the season it was based on what was available. Our dogs are not strict carnivores, they are omnivores, even wolves will eat various fruits and vegetables.
Besides the fact that dog’s and wolves’ microbiomes are different, or dogs split from wolves thousands of years ago, there are several genetic differences.
“In conclusion, we have presented evidence that dog domestication was accompanied by selection of three genes with key roles in starch digestion: AMY2B, MGAM and SGLT1. Our results show that adaptations that allowed the early ancestors of modern dogs to thrive on a diet rich in starch, relative to the carnivorous diet of wolves, constituted a crucial step in early dog domestication. This may suggest that a change of ecological niche could have been the driving force behind the domestication process, and that scavenging in waste dumps near the increasingly common human settlements during the dawn of the agricultural revolution may have constituted this new niche.” (Axelsson 2013)
I would like to draw special attention to “Relative to the carnivorous diet of wolves.” It doesn’t mean they are great at it, it just means they are better at it compared to wolves.
In another study they found wide variation in the number of AMY2B genes in various breeds. (Pajic 2019) For example while a Greenland Sledgedog had a mean of 4.263 the English Springer Spaniel had a mean of 17.25 (Arendt 2014). There were also differences based on the region where the dog evolved. The number of copies is correlated to the amount of salivary amylase.(Arendt et. al. 2014).
“Overall, native dogs from regions that overlap with the geographical spread of prehistoric agriculture carried significantly more gene copies (median 2nAMY2B=10, n=60, range: 3–22, s.d.=3.0, PWilcoxon<1 × 10?15) compared with dogs from the remaining three non-agrarian regions (that is, from Arctic America, Arctic Asia and Australia; median 2nAMY2B=2, n=54, range: 1–13, s.d.=2.4). High copy numbers in the agrarian New Guinea Singing Dogs (median 2nAMY2B=9.5, n=4, range: 9–22) compared with the closely related non-agrarian Australian Dingoes (mean 2nAMY2B=2.1, n=25, range: 2–3) comprise a particularly striking example of this pattern.” (Arendt 2016)
Now some of the breeds only had a couple samples. However, more and more people are getting their dogs DNA tested; this should give us a better picture of each breed’s number of copies.
Worldwide AMY2B copy number distribution. (a) AMY2B copy numbers in 392 dogs are bimodally distributed with a major mode of 9 and a minor of 2. Red and blue colours depict dogs originating in agrarian and non-agrarian regions, respectively. Purple marks the overlap between agrarian and non-agrarian copy number distributions. (b) Box plot showing the AMY2B copy number distribution in 46 dog breeds and 114 native dogs grouped into 8 geographical regions (Africa, South West Asia (S.W. Asia), South Asia (S. Asia), East Asia (E. Asia), South East Asia (S.E. Asia), Australia, Arctic America and Arctic Asia). Horizontal bars display median copy number values and boxes represent the interquartile range (IQR), with whiskers extending to maximum and minimum values within 1.5 × IQR. Black squares mark outliers. (c) Average AMY2B copy numbers in all dogs grouped in 10 large geographical regions: Europe, Africa, South West Asia, South Asia, East Asia, South East Asia, Australia, Central America, Arctic America and Arctic Asia. Dashed lines mark the approximate extension of prehistoric agriculture (Diamond and Bellwood, 2003) and colour marks regions that were sampled in this study and characterized as either agrarian (red) or non-agrarian (blue). (Arendt et al 2016 )
This ultimately means that different breeds are better equipped to digest carbs. As of right now there is no link between copy numbers and diabetes, but this could be a result of small sample sizes.
There is an old phrase “Just because you can doesn’t mean you should.” Given the fact that dogs can the real question is should they, and if so in what amounts? If they should, does the amount need to vary with the number of copies in each breed.
There is one other thing that needs to be considered and that is, nature has different things in mind for wolves. The goal of wolves is constant reproduction, and their high-protein diet is excellent for repeated reproduction. When it comes to our dogs, we have other things in mind. One, most dogs, are not intended for breeding, with an overwhelming majority of dogs in the United States being either spayed or neutered and two, we want them to live as long as possible. At the end of the day a diet where the dry matter is 65% Proteins and 25% Fat 7% Ash and 3% Carbohydrates and Fiber is probably not ideal over the course of a dogs life, and there are still things that need to be investigated in regards to the long term effects of the ketogenic diet on bone health.
Now We have seen the way pet food companies have loaded the diets with carbs. Like a pendulum this caused people to swing to the complete opposite side. They have been led by social media to believe that carbs are bad. That our dogs and cats don’t need them. That all they need is meat. Unlike the pendulum, however, it never settled in the middle. I do believe part of the reason this occurred is the melamine crisis back in 2007. I believe many people just lumped anything and everything together under the grain, and thus carbs are bad. I also believe this is part of the reason why grain free took off at such a great rate. We need to avoid these types of overly simplified arguments. Almost everything in life is not black and white; there are always shades of grey. When we oversimplify things we remove all nuisance from the discussion.
Like everything in life, there is a line. Life is about finding the right balance. It’s about finding the happy medium. Do our pets need carbs to survive? Well, we do know they don’t need as many carbs as companies have been putting in their foods.
Grain Grain-Free Ancient Grains
Now one thing I find interesting is the rate at which grain-free companies created grain inclusive lines. Many of the companies released ancient grain foods in just 2-4 months. What this tells me is there wasn’t much thought behind the process it was simply a reaction. They were just in a rush to release the product. Many Grain Free foods simply added Taurine. The grain inclusive lines used ancient grains because well they couldn’t use traditional grains that they said were bad. Now Farmina has had grain-free and grain-inclusive lines for awhile. Canine Caviar has used ancient grains in a couple of their formulas for several years. I’m sure there are others.
One thing of note is that if Nestle or Mars actually believed grain-free was the issue why have they not discontinued their grain-free lines.
One thing I feel has been missing in the grain fee, or grain debate is concentrating on the amount that is included, concentrating on the amount of fiber in the foods. Concentrating on the amount of protein that actually comes from meat.
Ultimately is swapping out Corn for Peas, or Peas for Millet or Potatoes for Quinoa really any better for a majority of pets excluding those that are allergic or are sensitive to the other ingredient. What are the effects when a percentage of protein comes from plants instead of meat?
As of right now DCM seems to be mainly an issue in the United States. There are still relatively few published peer-reviewed studies. As much as we would like there to be a simple cause ie grain free it is likely far more complicated. DCM is likely multifactorial. Meaning it is likely influenced by several factors ie genetics, environmental, previous health issues, and yes diet etc. It also appears to mainly be an issue in the United States.
Below is a table that details the protein provided by various ingredients included in grain, grain-free, and ancient grain.
Protein per 100 Grams
One thing to note about the above table is that these are the whole ingredients. Many of these ingredients, however, are included in parts ie corn meal gluten, pea protein etc. Corn Meal Gluten for example is 67.8% Protein on a Dry Matter Basis while Pea Protein is 83.7% protein on a Dry Matter Basis. If you would like to look at a specific ingredient the link below will allow you to search for many of the ingredients used in pet foods. Table data (dry matter) | Tables of composition and nutritional values of feed materials INRA CIRAD AFZ (feedtables.com)
As we have seen over the past several years, there is a risk of aflatoxin with corn. In my opinion, this is the main risk of pet food companies using corn. There is also the fact that it is higher in sugar, and much of it is genetically modified. But those are for another day.
Ultimately every ingredient choice in food has positives and negatives. It is on pet parents to read the ingredient labels and consider all of the factors. Is your breed prone to developing diabetes or becoming overweight? Did the dog evolve on a diet higher in fat? Were the carbs in the dog’s evolutionary history corn, wheat, rice, potatoes etc. It’s entirely possible that some dogs do better on grain-free and other dogs may do better on foods with grains. It all ultimately comes down to the dog in front of you.
How much of the energy should come from Protein, Fat, or Carbohydrates? No one has the answer to the ideal amount. It could vary between different breeds, there could also be seasonal variations as to the ratio. At the end of the day, it is up to you to decide the best amount for the dog in front of you.
A note on Filler Ingredients.
Some people argue that filler ingredients mean they are void of nutritional value. There are very few things that are genuinely void of nutritional value. While we may not like various ingredients, they aren’t void of nutritional value. This is a terrible and unworkable definition, as it’s far too reductionist. Fiber is commonly referred to as a filler ingredient, and while fiber might not be technically an essential nutrient, it does play an important role in health, especially as it relates to the microbiome.
At the end of the day, it comes down to the amount that is included in the food. Whereby its inclusion rate exceeds the benefit provided by having it.
Do Dogs need Carbs: The Case for including things other than meat
We need to find that happy medium. We know that fiber is important. We know there are benefits of eating fruits and vegetables for ourselves. We know how both the Ketogenic diet and Carnivore Diet can negatively impact the Gut Microbiome especially when fed long tetm. Yet, we don’t think the same is true for our pets. Part of the problem is that everything that isn’t meat got lumped into the bad category.
We ultimately shouldn’t be debating whether or not dogs need carbs to survive. We need to be debating whether they can benefit our dogs and cats. We need to move past the idea of just survival. AAFCO, NRC, FEDIAF Guidelines are all based on the prevention of outright nutritional deficiencies.
We need to change the conversation to what we can do to help them live longer. We need to focus on what we can do to help our pets thrive not survive. Despite all of our advances, there has not been a significant shift in life expectancy, and when we account for the likely reduction in early life mortality, its even lower.
When designing our pet’s diets and even our own diets, we all too often think in overly simplistic terms. We pay too much attention to the Macros. We pay too much attention to the amount of Protein, Fat, Carbohydrates, and to a much lesser extent vitamins, minerals, type of fats, and Amino Acids.
Now, some concentrate on getting the right amount of micronutrients. However, even this approach is incomplete because we still neglect the small compounds provided by various, grains, fruits, vegetables, Herbs, Spices, etc.
We neglect Terpenoids such as Lutein or Zeaxanthin found in Kale. We neglect the various Flavonoids, We neglect the various phenolic acids. We neglect things like curcumin or gingerol. We neglect the quercetin provided by Apples. We neglect the digestive enzyme Bromelain from the stem of the pineapple. We neglect Silymarin from Milk Thistle and countless other compounds.
Now, in a lot of compounds, the research is mixed. For example, the evidence around Glucosamine and chondroitin is nowhere near as clear-cut as many people would have you believe. It is possible, however, that they work better as a preventative than as a treatment. this would require a lifelong study.
More research is investigating the potential anti-cancer properties of various fruits and vegetables.
While Science may not have a complete understanding of all of these compounds yet, that doesn’t mean we shouldn’t incorporate them into our pet’s diets.
There is strong evidence for the benefits provided by curcumin provided it is given with black pepper or a fat such as coconut oil to increase absorption.
More research is investigating the potential anti-cancer properties of various fruits and vegetables.
By including various fruits and vegetables, it represents a shift toward being proactive in the health of our pets instead of just being reactive.
We need to move past the argument of whether dogs need carbs. We need to shift the conversation to whether various carbs benefit our pets. Can they help our pets thrive? If the answer is yes, then what amount?
While the research is mixed on various compounds, that doesn’t mean they shouldn’t be included. Like Pascals Wager, we and our dogs lose little to nothing by including different fruits and vegetables in their diet, there is only a potential benefit. If there is even a small chance that it will prolong our pet’s life; If there is even a tiny chance that it reduces the risk of developing cancer or any number of other diseases it's well worth it especially when there isn’t a downside. Now, this doesn’t mean go crazy and make it 60% of their diet.
The conversation needs to move away from just essential, survival, minimum, or adequate to prevent deficiencies, but what is optimal, and what levels help our pets thrive. What helps them live longer? As long as the conversation centers around minimums or whether something is essential no progress will be made.
A note on “Superfoods”
Frequently you may see various superfoods pictured on the label. The problem is they are included in such a minuscule amount where they aren’t going to confer any potential benefits. Are three or four blueberries in a 25lb bag of food really conferring any benefit even before you account for the effects of processing?
Arendt M, Cairns KM, Ballard JW, Savolainen P, Axelsson E. Diet adaptation in dog reflects spread of prehistoric agriculture. Heredity (Edinb). 2016 Nov;117(5):301-306. doi: 10.1038/hdy.2016.48. Epub 2016 Jul 13. PMID: 27406651; PMCID: PMC5061917.
Arendt M, Fall T, Lindblad-Toh K, Axelsson E. Amylase activity is associated with AMY2B copy numbers in dog: implications for dog domestication, diet and diabetes. Anim Genet. 2014 Oct;45(5):716-22. doi: 10.1111/age.12179. Epub 2014 Jun 28. PMID: 24975239; PMCID: PMC4329415.
Axelsson, E., Ratnakumar, A., Arendt, ML. et al. The genomic signature of dog domestication reveals adaptation to a starch-rich diet. Nature 495, 360–364 (2013). https://doi.org/10.1038/nature11837
Pajic et al. Independent Amylase Gene Copy Bursts Correlates with the dietary preferences in mammals. eLife 2019;8:e44628. DOI: https://doi.org/10.7554/eLife.44628