Updated November 23, 2021
Have you been told you should change your dog to a grain-free or a low carbohydrate diet? Perhaps you’ve wondered why vets are fairly quiet about it all. I’m going to show you some evidence that might just ease your mind
I have a lot of sympathy for the low carb diet revolution. I’ve been in the same place myself. In my first two years of being a vet I was lucky enough to work in the veterinary department of a zoo, and we had the huge responsibility to design nutritional plans. For some species we were the first people to do this. Ever.
Designing A Diet
How we did it worked every time; we went back to nature. Just like the low carbohydrate movement is doing for dogs.
We pulled out the biological data from field studies, showing which foods were eaten in the wild both by observation of the animals’ behaviour and their droppings.
Now, for a dog, we turned to the wolf, its closely related ancestor. See if you can spot the problem.
Wolves consume a diet very high in prey animal species, supplemented by fruits, insects etc. Therefore, the best diet for dogs should be mainly of animal origin with small amounts of vegetable matter.
This is logical but deeply flawed. What is the mistake?
Dogs Are Not Wolves
In 2013, an article in the journal Nature laid bare the 36 main regions in your dog’s DNA that have mutated from the wolf. Nineteen of these govern behaviour, allowing domestication. Amazingly, another ten are involved in changes in digestion. Guess what new foods they help digest?
The authors concluded: “Our results indicate that novel adaptations allowing 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 the early domestication of dogs.”
In other words, dogs have evolved to adapt to a diet rich in carbohydrates
This is no surprise. Dogs are our first domesticated species, long before cows. We developed a tolerance for lactose in an even shorter time, showing how evolution can occur over surprisingly short timescales.
We think that wolves began to turn into dogs when they started scavenging near human settlements. Here, meat is scarce, and individuals who survive on human foods are most likely to prosper. This creates a strong selection pressure for new digestive abilities.
Are Carbohydrates Good For Dogs?
So dogs may be able to digest carbohydrates but are they any good for dogs? Here are a few ways:
- Rice is a great way to help settle a mild stomach or intestinal problem.
- Feeding carbohydrates allows us to keep fat and meat levels lower. Fats are definitely dangerous to many dogs (read about pancreatitis here) and high red meat diets have been linked with cancer and dysplasias, though not conclusively (Alenza et al, 1998).
- Dry kibble foods made using carbohydrates store well and require minimal preservatives.
- Grain proteins contain methionine, a limiting amino acid in the legumes used in many vegan dog diets.
However, on the converse, there is probably no requirement for carbs in a dog’s diet. Some people believe they cause harm. There are four concerns: obesity, diabetes, allergies, and inflammation.
- Obesity: Whether or not weight gain is more likely on high-carb diets is missing the point. Show me the dog that can be allowed to eat as much as they want of any type of food without getting fat. Read more here on managing weight gain in dogs.
- Diabetes: Our clinic has the records of 6800 dogs, but only 22 of these had diabetes, all type 1. Dogs don’t get type 2 diabetes and it’s therefore not likely that foods play a big role. Read more about diabetes here.
- Food Allergy: There will be some dogs who develop either skin disease or gastrointestinal problems due to carbohydrates, as there will be to all dietary ingredients. This page shows the evidence for exactly what the common dog food allergies are.
- Inflammation: A very common concern is that carbohydrates cause inflammation, leading to arthritis, liver failure etc. Here’s an example from an online dog health forum:
“I was told the same thing, and there’s plenty of information all over the net about how grains cause inflammation. Would you believe the arthritis foundation in Australia, however, doesn’t support this, stating there’s no real evidence arthritis symptoms are worsened when eating grains…”
That’s really the crux of the matter: there’s absolutely no good evidence for any of these harmful effects. If scientific evidence appears in support of the idea that carbs are unhealthy, I will be the first to let you know.
Until then, don’t worry.
Are Low Carb Or Grain-Free Diets Healthy For Dogs?
Simple answer: yes, I think so. Dogs are highly adaptable and if a dog is healthy and happy on a diet, I’m happy too. Most of the time, grain-free diets are perfectly suitable. Though being “grain free” doesn’t necessarily mean low in carbohydrates, or that grains are harmful.
If feeding regular kibble isn’t for you, I can suggest three options:
- I quite like the BARF diet. If this interests you, please read our veterinary guide to raw diets.
- If doing it yourself, visit this page for a homemade raw dog diet I created. Although there’s no guarantee, I think it’s better than most.
- Similar mixes can be purchased from specialised dog food stores in Adelaide.
What about my own dogs? I love feeding my dogs fruits, veggies, and raw bones but I rely on a diet with a balanced mix of protein, carbohydrate and fat levels. When it comes to which dog food, I believe by choosing a high-quality manufacturer I get better quality proteins more available for my dogs to digest.
Should I Feed Meat?
What I never do is feed them extra meat. Why not?
- Their dog food (I use Hills Vetessentials) contains sufficient meat for their lifestages.
- Some raw meats can be contaminated with Salmonella and E. coli. It’s not just your pet that’s at risk.
- I see fussy dogs getting very high meat levels who end up having gastrointestinal upsets that respond to removal of the extra meat. Many clients have heard me say: “You’re feeding your dog like a cat”.
Now cats are a whole other story. Read about carbohydrates and cats here.
Articles available on request
Alenza, D. P., Rutteman, G. R., Peña, L., Beynen, A. C., & Cuesta, P. (1998). Relation between Habitual Diet and Canine Mammary Tumors in a Case‐Control Study. Journal of veterinary internal medicine, 12(3), 132-139.
Axelsson, E., Ratnakumar, A., Arendt, M. L., Maqbool, K., Webster, M. T., Perloski, M., … & Lindblad-Toh, K. (2013). The genomic signature of dog domestication reveals adaptation to a starch-rich diet. Nature, 495(7441), 360-364.
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By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These articles are from a series regularly posted on email and Twitter. Subscribe via email here to never miss a story!