Could vegan dog food help save the planet?

Professor Andrew Knight

THE PACK Speak To Professor Andrew Knight About His New Research On The Environmental Sustainability Benefits Of Vegan Dog, Cat And Human Diets


Yesterday, a groundbreaking scientific paper by Professor Andrew Knight on The Environmental Sustainability Benefits Of Vegan Dog, Cat and Human Diets was published in prestigious journal PLoS One, revealing the relative benefits for environmental sustainability of vegan diets for dogs, cats and people. In an exclusive interview, THE PACK pick the brains of Professor Andrew Knight on the importance of his findings and what this new data might mean for the future of plant-based dog food.

Andrew, your new research finds that:

  • Transitioning all dogs to nutritionally-sound vegan diets would spare as many as 6 billion land animals (and billions of aquatic animals) from slaughter, as well as significantly reducing land and water use, greenhouse gas emissions and biocide use.
  • You found that all dogs being 'vegan' would free up land larger than Saudi Arabia or Mexico and save freshwater volumes greater than all freshwater use in Denmark.
  • Vegan dog diets would reduce GHGs (greenhouse gases) by amounts greater than all GHG emissions from South Africa or the UK.
  • And finally, the numbers of additional people who could be fed using food energy savings associated with canine vegan diets exceeded the 2018 human populations of the entire European Union, which was over 512 million people


These are staggering statistics, confirming what we've always believed at THE PACK - that feeding our dogs plants instead of meat is a critically important way to save our planet and other animals. What impact do you hope this new paper will have?

I think these results are game-changing for the discussion about plant-based diets that has been prominent within society, particularly among those who care about the environmental impacts of farming. We know that the livestock sector is responsible for vast amounts of land use, deforestation, water use, water pollution, greenhouse gases and so on. In response, there have been many calls for human diet change, but virtually no calls for diet change for dogs or cats. This is partly because of the assumption that they consume relatively few livestock products, and that what they do consume is mainly by-products of human food production and is therefore beneficial ‘recycling’. But actually, what this study shows is that the only benefit of using byproducts within meat-based pet foods is that they're cheaper than human-grade meat. The actual environment impact of using by-products is greater than if pets were to be fed human-grade meat. This is because using byproducts requires more livestock animals to produce, than producing human-grade meat. It’s less efficient on a per-carcass basis.

So, the use of byproducts actually increases the ecological pawprint of pets, rather than decreasing it. These are major findings of this study: that the use of byproducts increases the environmental impact and, actually, the environmental impact of dog food is really substantial. Globally, at least 8% of livestock consumption is for dog food, so we are quite wrong to assume that we don't need think about pet food during discussions about food system change.

Feeding byproducts decreases the cost of pet food. But it lowers the quality of the ingredients these poor dogs are consuming, and it significantly worsens the environmental impacts. 

Do you think that these findings will filter down to kind of your average, environmentally conscious pawrent? Do you think that will have genuine impact in changing the way that people feed their dogs?

Yes! I very much hope that these scientific results will get widely reported to dog guardians, as well as to the veterinary and pet care industries. I will do my best to get the message out, but I very much rely upon the help of all who care about dog health and environmental sustainability, to get this key information widely disseminated. 

These results are especially exciting because this data’s relevance is no longer limited just to pet guardians; the study provides key new results about the environmental benefits of human dietary change too. That means it has wider interest; after all, everybody should be concerned about environmental sustainability and climate change, nowadays.

The study we published last year on health outcomes in dogs for vegan diets was reported in more than 400 news outlets globally. And this study has potential to be even bigger! 

It’s really important that the message does get out there. Climate change, biodiversity loss and environmental degradation are the key issues for our generation and the ones that will follow us, and this publication is key to addressing one of the major known causes, which is the livestock sector.


Papers have been published on environmental sustainability of plant-based pet food before, by yourself and researchers like Okin. How does this new research advance the field/show something new? What do you believe to be your most significant finding?

We have not had information about the ingredients used in pet food on a large scale until very recently, and this is the first large, published study to make use of all that data. It utilised an industry report that covered two-thirds of all pet food produced in the US in 2018 to 2019. From this detailed information about pet food ingredients I was able to calculate how much of the pet food was by-products etc., and how much wasn't, and what livestock species were being used. That allowed me to work out how many average livestock animals were required to produce all of that food for dogs, and then calculate what the environmental impact was, in comparison to livestock consumption by cats and people.

So the major advance here was the ability to analyse, in detail, the actual ingredients used in pet food, and the consequent level of consumption of livestock animals, and the resultant environmental impacts.


You found that, globally, dogs consume 7.7% of livestock animals compared with humans who consume 91.1%. Did this figure surprise you? Is it more or less than you expected?

I think it’s surprising to see that dogs, in particular, consume such a large bite of the ‘livestock pie’. They consume billions of livestock animals and accordingly have major ecological pawprints. The study also reviews all previous studies in this field, and several of those have shown that the dietary consumption of an average sized dog is roughly equivalent to that of an average human consumer. This does vary a lot across dog sizes (large breed dogs have much, much greater pawprints than small breeds). 

It’s important to note that I had a choice at multiple steps during the calculation process to take more or less conservative options, and I always chose the most conservative option possible. So, I think that the true environmental impacts of dog food are actually larger than those found in my results; probably substantially larger. Conversely, the benefits of transitioning them on to nutritionally-sound vegan diets, are probably much greater than shown in my study – which already shows very large benefits.


Why do you think major retailers aren't already stocking plant-based pet food? Will this new data help?

I think this change is coming. I believe we're at the start of an exponential growth curve for vegan pet foods. Two years ago, I had pet food startup companies coming to me about once every three months requesting a summary of the research data. Now, it's once a fortnight. The speed at which new companies are coming into this area is notable.

UK Pet Food – the trade association for nearly all UK pet food manufacturers – only recently updated their factsheet confirming that nutritionally-sound vegan pet foods are a legitimate product, and that dogs and cats can thrive on these products. The British Veterinary Association hasn't yet updated their policy of opposition to these diets, but they are reviewing all their information at the moment, in light of the wealth of recent scientific evidence showing equivalent or superior health outcomes for dogs and cats using vegan diets. Change is happening, but it’s not going to take place overnight, where all the supermarkets suddenly have good availability of these brands. In fact, I’m hearing of shortages of vegan pet food in various regions of the world, and we know that consumer convenience is a key factor in determining whether products like these succeed. It’s therefore really important that this is addressed. 

I think we’re seeing the teething problems that occur when a disruptive industry first emerges, and new products become available. There’s always a period when demand outpaces supply, and supply needs to catch up. We're going through that at the moment with vegan pet food. 

Even people who don't particularly care about animal welfare often do care about environmental sustainability. Major corporations sometimes do (as part of their corporate social responsibility policies), so this study being published and widely reported will add enormous impetus to the change that is likely to occur in this area.

What do you see as the best plant-based diet for a dog? Oven-baked, extruded, cold-pressed, wet?  Does it matter?

From an environmental perspective, it makes a really big difference. I didn't examine this in my particular study, but I did review all of the other studies on plant-based dog food. Several had calculated relative environmental impacts, and they were vastly greater for wet food than for dry food. 

Regarding the dogs consuming these diets, the important aspects are that the food is nutritionally sound, and the animal is enjoying their food. There's no evidence to indicate any widespread difference in nutritional soundness between wet and dry or differences in palatability. Sometimes there are medical conditions for which the pet needs to eat dry or wet. As a general rule, if a dog is overweight, I suggest a wet diet, because of the higher water concentration which helps to expand the stomach and make the animal feel satiated without providing calories. Whereas if there's a dental problem, generally dry biscuits or kibble may be more helpful to scrape the teeth clean.


Do you have any advice to pawrents wanting to feed their dogs plant-based but not sure where to start?

I always recommend people try to choose a reputable company who are working with veterinarian nutritionists or PhD nutritionists, to ensure that the product is nutritionally sound. These companies should be able to provide some kind of information about reasonable steps that they're taking to ensure nutritional soundness and good quality. If a company doesn't have any information on their website and won't respond to queries, that should be a red flag and you should go somewhere else. Of course, it's basic and essential that the product has to be labelled as being nutritionally sound: not intended as a treat or snack but rather as a complete diet. “Nutritionally complete” and “Nutritionally balanced” are both terms that indicate that. 

Here's some advice about gradual transitioning as well. Some dogs tend to eat first and ask questions later(!) but you should generally resist that and gradually change their diet over a couple of weeks. This allows more time for their digestive enzymes and bacteria in their intestines to transition, reducing the potential for adverse reactions such as diarrhoea.

You've published a series of exciting papers about vegan pet food over the last few years. Are you able to give us any hints about what you're working on next? 

Yes. I have a series of exciting studies coming, examining aspects such as canine health outcomes, economic impacts for pet guardians of lowered medication use and veterinary visits, and other aspects. I’ll continue to post study summaries once published on and my social media. 



Are you inspired by Professor Andrew Knight's study? If so, then we're here to help to transition your dog towards their new plant-powered lifestyle. 

Get 20% off your first order of our delicious wet food with code THEPACK20 

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All Pre Orders are automatically entered into our giveaway to win 1 YEAR OF FREE DOG FOOD worth OVER £1,000. 

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