Monday, May 22, 2017

That Vegan Sled Dog Study

Whilst researching daily dental dog chews, I found myself on the V-Dog website. As a former militant rawfeeder, I've never considered vegan dog food worth researching. I decided to check out their guaranteed analysis, and quickly determined that their foods do not contain nearly enough fat for my working dogs. Their FAQ page is really interesting, though. It cites a couple of peer-reviewed scientific journal articles that definitely deserved a closer look.

Vegan Sled Dogs?

Distance-racing Alaskan sled dogs have an amazingly high metabolic rate and energy expenditure when working for extended periods in cold weather. They have been used in various experiments studying the effects of different parameters on performance, sometimes with surprising results. A study in 2009 on racing sled dogs is rather well-known, but it's worth pointing out that this experiment was done on purebred Siberian huskies doing sprint races in mild weather in Australia. The study compared blood test results between dogs that were fed a commercial meat-based performance diet, and those fed a diet with the same nutritional parameters but no meat. The experimental diet used soybean meal and corn gluten as protein sources. The dogs did fine on both diets, their performance didn't suffer and their blood parameters remained the same.

Nutritional Equivalence
Carrot-shaped durable chew toy
Photo by Erin Koski

This study is widely cited by purveyors of vegan dog foods, as evidence that dogs can be perfectly healthy without consuming animal products. I don't have a problem with that claim, but I do have a problem with the vegan dog food choices out there, and how they compare to the foods used in the experiment. Essentially, the study proved that a specific meat-free diet was suitable, and the dog food companies like to cite it as evidence that all vegan dog foods are suitable.

Here's the details, for those that don't feel like fishing through the paper to find them. The commercial diet used was Pedigree Advance's formula for performance dogs. When I first read this paper I thought they must be using regular old Pedigree dog food in the big yellow bag, because that's the only food the company sells here in the USA. However, Pedigree actually sells much higher-quality products in other countries. The study was published in the British Journal of Nutrition, but the actual experiment took place in Australia. The Pedigree Advance product line sold in Australia includes and Active Adult formula that contains no by-products, and has 32% protein and 22% fat. This is a huge difference from the 21/10 food sold here.

The experimental meat-free diet used soybean meal instead of chicken meal. Both diets also used corn gluten, but the meatless diet had quite a bit more. Both diets were made in a commercial facility, with the nutritional analysis as similar as possible. Both diets contained 32% protein and 22% fat. That's a good ratio for active dogs, but it's not what you'll find in commercially-available vegan dog food on the market today. If you want to feed your dog vegan kibble, your options are 24/10, 18/8, 20/10, 22/8, or 17/8. There is no high-protein, high-fat vegan dog food out there. Clearly, vegan dogs are supposed to be sedentary housepets on extremely carbohydrate-heavy diets.

What about That Retrospective Study?

Another journal article widely cited by people advocating vegan diets for dogs was published in an MDPI public access journal. This is already slightly suspect, as the reliability of MDPI journals has been repeatedly called into question. Basically, they will probably publish anything if you pay them enough, and their peer review process may not be rigorous or thorough. With that in mind, the publication of this retrospective starts to make sense.

I have issues with nearly every section of this article. When discussing studies showing inadequacy of vegetarian pet diets, the authors are quick to point out that anything published more than ten years ago is likely out of date. However, when discussing the inadequacy of meat-based commercial diets, the authors freely cite papers from two and three decades prior with no such caveats.

The authors include information from such biased sources as the People for Ethical Treatment of Animals, books by vegan authors, and even vegan websites. Much of this information has to do with the evils of meat by-products, which demonstrates a lack of ingredient integrity in very low-quality products rather than an inherent evil of meat-based pet food. Meat-based pet foods in the same price range as commercial vegan pet foods are almost certainly not going to contain any of these horrors anyway, so the whole issue is a bit of a red herring.

While the sled dog study mentioned above shows some compelling evidence that dogs can be healthy on a vegetarian diet, the retrospective study simply shows that there is very little conclusive information out there. What information does exist is from small-scale studies, extremely biased sources, or poor-quality studies like pet owner surveys. Decent-quality meat-based pet foods are fine. Well-researched vegan pet foods are also fine, as long as you don't mind feeding a low-fat, low-protein, carb-heavy diet. If you want to build muscle or maintain a working dog, you probably need to feed a meat-based food formulated for active dogs.

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