The food sector – and the animal agriculture sector in particular – is a significant and neglected contributor to rapid climate change. Latest estimates indicate that the production of animal-based foods is responsible for at least 20 percent of anthropogenic GHG emissions (though some studies put this figure much higher). This is expected to increase as animal product consumption increases globally.

The environmental impact of pet food

In wealthy nations like the US, dogs and cats consume at least 20 percent of all farmed land animals. Given its relatively high consumption of animal-based ingredients, the pet food sector is associated with substantial environmental impacts. This poses a significant challenge for environmental sustainability. But it also represents a largely untapped opportunity to mitigate the “pawprints” of our dogs and cats.

In this article, we summarise the findings of our recent study, one of the first comprehensive studies exploring the environmental impacts of pet food (Nicholles and Knight, 2025). We examine the impacts of meat-based pet food, and the benefits of a transition to more sustainable non-animal alternatives. We conclude that the most effective measure we can currently take to mitigate the environmental impacts of companion animal diets is to transition dogs and cats to nutritionally sound vegan pet foods. 

It is now clear that the importance of dietary change to combat the climate crisis is not limited to humans: we must also address what we feed to our companion animals.

Companion animal diets 

The global companion animal population is vast. Over 50 percent of households worldwide have a dog or a cat – the two species which make up 95 percent of pet food sales. Global dog and cat populations have recently been estimated as reaching 1 billion animals. Domestic dogs have a collective biomass of about 20 million tonnes, roughly equal to the combined biomass of all remaining wild terrestrial mammals. Cats have a total biomass of two million tonnes. Such large numbers of animals require a huge quantity of food resources.

What’s more, we can expect these numbers to increase significantly. As countries develop, people tend to have fewer children, and have more disposable income to spend on companion animals. We can see this in pet food sales trends: the global pet food ingredients market is expected to increase from USD $32.2 billion in 2022 to $44.5 billion in 2027.

From the food they eat, to the feces they produce, to accessories and services designed for them, there are a range of environmental impacts associated with caring for a dog or cat. However, the vast majority of these impacts come from pet food, and specifically the type of pet food (i.e. the ingredients) being fed. 

In other words, when it comes to the environmental impact of pets, what matters most is: what are we feeding them? 

What is the climate cost of meat-based pet food? 

Most pet food consumed globally is meat-based, and this comes with significant environmental impacts. Just over half – 53.1 percent –  of all ingredients in pet food are animal-based. These include human grade products such as meat, fish, dairy, and egg products, and non human-consumable products (also known as animal byproducts), predominantly meat and bone meal. Globally, 74.9 percent of animal-based ingredients are animal byproducts (largely used because they are cheap), whereas this number falls to 50.8 percent in the US, where wealthier consumers are more able to afford more premium diets using higher levels of human grade ingredients. 

Perhaps unsurprisingly, such a reliance on animal-derived ingredients leads to significant environmental impacts. In the US, 25-30 percent of the environmental impacts of livestock production within the US have been attributed to companion animal diets. 

While estimates on the impacts of meat-based pet food vary, all studies on this subject agree these cannot be ignored. One found that, in Japan, the environmental impacts of a medium dog’s diet were greater than that of the average Japanese person’s diet. For a large dog, they were greater than the average Japanese person’s entire environmental footprint. 

This is undoubtedly a challenge for environmental sustainability. But it’s also an opportunity. Because the environmental impact of pet food is currently so high, there are significant opportunities to mitigate these impacts. In countries with high rates of companion animals, like the US, the benefits achieved by transitioning dogs away from meat-based diets is equivalent to one quarter to one third of the environmental benefits achievable through human dietary change. 

Read more: Is 2025 The Year Of Ethical Dog Food?

What about animal byproducts?

Until recently, the environmental impact of pet food was dismissed as negligible. Pet food relies heavily on animal byproducts, and it was generally assumed that these ingredients would be wasted if not used in pet food.

Claims like this have been repeatedly criticized. They wrongly assume that animal byproducts would be wasted in landfill if not used in pet food. The argument also assumes – crucially – that animals must be farmed in the first place.

In fact, only 25 percent of animal byproducts produced in high-income countries like the US are used in pet food, and the sector competes with various others for these ingredients. Animal byproducts are used in pet food not because they would otherwise be wasted, but instead because they are cheaper than human grade cuts of meat. The sale of animal byproducts helps prop up slaughtering industry profits. 11.4 percent of the gross income from beef is from byproducts, and 7.5 percent for pork. 

Moreover, as we showed in 2023, animal byproducts are less efficient than human grade meat. This is because animal byproducts only make up a minority of the average animal carcass used for pet food (39.2 percent for dogs, and 31.3 percent for cats). Compared to using human grade meat, using animal byproducts in pet food requires 1.4 times more animal carcasses for dog food, and 1.9 times more for cat food. As a result, more livestock animals are required (and with them, greater environmental impacts incurred) to feed dogs and cats animal byproducts.

Given this, it is more reasonable to view these animal ingredients as coproducts rather than byproducts. In doing so, they are acknowledged as valuable commodities in and of themselves, rather than externalised byproducts that can be excluded from environmental impact calculations. 

In summary, the idea that we can dismiss the environmental impacts of pet food because they use animal byproducts that would otherwise be wasted, is entirely false. It incorrectly assumes that animal byproducts would be wasted if not used in pet food, and it fails to recognise that these actually incur greater environmental impacts, compared to human grade meat. 

In reality, the best way to reduce the environmental impacts of our companion animals’ diets is to transition them away from diets high in animal products, towards nutritionally sound vegan ones, or those based on cultivated meat once they become more widely available. 

Read more: Plant-Based Dog Food Brand Wins Dragons’ Den Backing

Environmental benefits of vegan pet food

Fortunately, a range of alternative pet food protein sources derived from plants, fungi, cultivated meat and microorganisms are emerging, and offer huge potential to reduce the environmental impact of pet food. Various plant-based pet food companies are already widely commercially available in the UK and other countries (a non-exhaustive list is available at www.sustainablepetfood.info). 

If we transitioned all dogs and cats onto nutritionally sound vegan diets, the benefits for environmental sustainability would be game changing. A global transition for pet dogs alone would save 1.5 times the greenhouse gases produced by the UK, as well as vast amounts of land and freshwater. The food energy savings would be sufficient to feed 450 million people – more than the entire EU population. At least six billion land animals would also be spared from slaughter annually, and another billion if pet cats were also transitioned. 

There are also some emerging pet food alternatives that may offer even greater environmental benefits. In February 2025, Meatly, a UK-based biotech company that makes cultivated chicken-based pet food, partnered with vegan pet food company The Pack to launch the world’s first cultivated meat pet food product for retail sales. And Calysta, a company producing animal-free pet food via precision fermentation, offers a product already at commercial scale with environmental impacts reportedly a fraction of those from plant-based ingredients, let alone animal-based ones. The first nutritionally complete pet food using their protein product was launched by Marsapet in February. 

What needs to change

The best thing we can do to reduce our companion animals’ environmental “pawprints” is to transition them to nutritionally sound vegan diets. Dogs and cats fed these diets seem to enjoy them as much as meat-based diets, and modern vegan pet foods are generally of equivalent, if not superior, quality and nutritional soundness to meat-based pet foods. Moreover, as we summarised recently in Plant Based News, there is a strong and growing body of evidence demonstrating that dogs and cats fed nutritionally sound vegan diets experience health outcomes as good as or better than those fed meat-based diets. Given these significant environmental and health benefits, there is no longer any sound reason not to support a companion animal dietary transition. 

Other mitigation strategies include choosing to care for small rather than large animals where possible, adopting instead of buying companion animals, and preventing overfeeding (which is currently common). Importantly, however, gains from reducing overconsumption will quickly be outpaced by rising companion animal populations globally. Hence, these are supplementary strategies that should be pursued in tandem with, rather than in place of, a wider structural transition to nutritionally sound vegan diets. 

Additionally, given the very significant environmental impacts associated with companion animal diets, public awareness on this topic is shockingly low. Along with governments and the mass media, those with large platforms in pet care or adjacent communities should communicate the environmental benefits of a transition towards vegan pet food to their audiences. For those resistant to the idea at first, a gradual transition (say, feeding 50 percent vegan and 50 percent meat-based pet food) would still significantly reduce an animal’s dietary “pawprint.” 

Addressing the impact of companion animal diets on climate change is an environmental imperative. We now have very good evidence demonstrating health and environmental benefits associated with modern, nutritionally sound vegan diets for dogs and cats. In light of this evidence, there is no good scientific reason not to support companion animal dietary change. Given the very significant potential to mitigate climate change and environmental breakdown, support from guardians, government, and industry is clearly warranted. 

Read more: Lewis Hamilton Says Bulldog Roscoe Is A ‘Different Dog’ Since Going Plant-Based

This article was written by Billy Nicholles on the PBN Website.

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When you think about meat consumption, you may not naturally think about canine and feline diets. But you have good reason to. Globally, nine percent of all farmed land animals are slaughtered for pet food. In wealthy countries like the U.S., where more people have companion animals, this rises to 20 percent.

This means that seven billion land animals and many (probably billions) more fishes* are killed every year to feed the world’s dogs and cats. And they have an environmental “pawprint” to match. If all the world’s dogs and cats went vegan, we could save more greenhouse gas emissions than all emissions from the UK and New Zealand combined. 

Until recently, it was assumed that we couldn’t mitigate the negative impacts of meat-based diets for dogs and cats, since they couldn’t maintain good health on a plant-based diet. But in recent years, a new, strong, and growing body of research is showing that dogs and cats on vegan diets generally enjoy health outcomes as good as or better than those on conventional meat-based diets. 

Given the benefits for farmed animal welfare, companion animal health, and environmental sustainability, it is becoming increasingly clear that we should transition our dogs and cats onto nutritionally-sound plant-based diets. 

Veterinary organisation criticizes vegan diets for dogs and cats 

But a recent blog authored by veterinary nurse Robyn Lowe of Veterinary Voices UK questions this research and the conclusion that dogs and cats should be fed a vegan diet. In her blog titled “Vegan Diets are Healthier and Safer for Cats and Dogs – Or Are They?,” she criticises many elements of this research and cautions against the use of vegan diets for dogs and cats.

It is worth noting that the veterinary community is becoming increasingly open to vegan companion animal diets. Earlier this year, in response to the weight of evidence supporting nutritionally-sound vegan diets for dogs, the British Veterinary Association ended its opposition to these diets. 

While healthy scrutiny and debate is welcomed in any scientific field, these criticisms are overblown and appear ignorant of the rigour of the research, and the importance of the findings for farmed and companion animals. Lowe neglects the broader literature, and focuses on limitations that were already acknowledged and mitigated in these studies. 

This is problematic. Rapid climate change and the growth of animal agriculture are both urgent global issues. The stakes are high, and avoiding confusion or misinformation is crucial. 

We therefore take this opportunity to counter the criticisms in Lowe’s blog, and clarify the findings of the research on whether we should feed our dogs and cats a vegan diet. 

Read more: UK Issues ‘Snake Warning’ – Here’s Why They Should Never Be ‘Pets’

Veganism isn’t an ideology

Lowe critiques two studies in the literature, both of which were large-scale survey based studies of dog and cat guardians authored by Knight et al. (2022; 2023). She begins by arguing that we should take this research with a pinch of salt simply because the lead researcher follows a vegan diet, which she describes as an “ideological position” which “inevitably introduces a risk of bias”. This claim is inappropriate and misleading. By this logic, if Lowe eats animals herself, should we caveat her critiques as being influenced by her inherent meat-eating bias? 

There is overwhelming scientific evidence that animal farming and fishing causes very significant suffering to trillions of animals annually, and is a leading contributor to the climate crisis. Veganism is not an ideological position – it is the logical scientific solution to the threats that animal agriculture poses. The fact that the lead author is vegan is not a sign of “ideological bias” and does nothing to detract from the rigour or credibility of this research, which is published in PLOS ONE, a leading peer-reviewed scientific journal. 

Lowe also points towards the studies’ funder – ProVeg International – as another reason to dismiss the findings, since ProVeg International advocates for a more plant-based food system. However, commercial funding of nutrition (and broader medical) studies is extremely common. Most research probably would not proceed without such financial support. In this case, the funder’s contribution was explicitly acknowledged, with the authors confirming that “this funder played no role in study conceptualisation, design, data collection and analysis, preparation of resultant manuscript nor decisions relating to publication”.  

Ignorance of the broader scientific literature 

Lowe cautions the conclusion that we should feed companion animals vegan diets by stating that “we are in the infancy of knowledge about these diets.” This reveals a lack of awareness of the other studies in this field. By late 2024 there were 11 studies, including multiple clinical and large-scale survey studies, showing health benefits for dogs on vegan diets, and three studies for cats. More information on all these studies is available here. 

On top of this, there is a systematic literature review on this topic that concluded there is “no overwhelming evidence of adverse effects” for dogs and cats on vegan diets and “some evidence of benefits.” It added that “beneficial findings were relatively consistent across several studies and should, therefore, not be disregarded.”

In reality, we now have more studies showing positive health findings for dogs and cats fed vegan diets than we do for many other commonly accepted diets and veterinary products, which are normally supported by very few, if any, published, peer-reviewed scientific studies. In contrast, by late 2024 there were 14 studies showing health benefits for dogs and cats fed vegan diets, as well as a positive systematic literature review. 

Lowe also briefly references a paper that finds nutritional inadequacies in vegan pet foods. However, this study was limited to the Brazilian market and so is not generalizable to the UK. A comprehensive global study analyzing the nutritional soundness of meat-based and vegan pet foods found that most are fairly well-made, with vegan pet food being slightly more likely to be nutritionally-sound and of good quality. 

What about cats? 

There is some confusion over the dietary needs of cats, and whether they require a meat-based diet.

Lowe states that “cats … are obligate carnivores, and therefore need specific amino acids to survive”. It is worth noting that dogs, and indeed humans, also need specific amino acids to survive (dogs need 10, and humans nine). 

Lowe continues that “cats lack the ability to synthesise (make) a number of important nutrients”. However this statement is applicable to dogs as well, and indeed virtually all species, which rely on obtaining certain nutrients through their diet. 

The key point is that cats (like any other animal) need certain nutrients, not certain ingredients, to survive. As obligate carnivores, some of these nutrients are not naturally occurring in plant-based foods. However, provided a vegan cat food is synthetically supplemented with these nutrients (such as taurine, or vitamin A) to ensure nutritional completeness, there is no reason why cats cannot meet all their nutritional needs on these diets. 

Indeed, to date, three peer-reviewed scientific studies using both large-scale survey and clinical data have found that cats fed nutritionally-sound vegan diets enjoy health benefits as good as or better than those on conventional meat-based diets.  

For those who feel wary about the idea of synthetic supplementation, it is worth noting that meat-based cat foods are also synthetically supplemented with taurine and other essential nutrients. This is because the high temperatures and pressures used during processing can degrade naturally occurring taurine, and other fragile nutrients. Synthetic supplementation is a standard and safe part of pet food formulation and is necessary to meet an animal’s nutritional needs. 

The benefits and limitations of survey-based studies

Lowe specifically criticizes two studies which used large-scale surveys to gather guardian-reported health data on dogs and cats fed meat-based and vegan diets. Many of Lowe’s criticisms relate to this methodology and its limitations. It is worth noting that the limitations of guardian-reported data were covered extensively in the studies themselves. For clarity, though, we address them again here. 

Guardian-reported data is valuable

Lowe argues that it is “expected” that vegan cats will score better on “all health measures” when using guardian-reported survey data. This is another example of sloppy reasoning. 

There were many more animals fed meat-based diets in both studies. If it was the case that you can always expect guardians to report positively about their animal’s health, we would actually expect the bias to skew results in the opposite direction, and show that meat-based diets were healthier. In fact, in both studies the opposite was found.

These surveys also contain very large numbers of respondents, which improves the reliability of the results and often allows for statistically significant results. In addition to guardian views on health (which can be prone to conscious and unconscious bias), more objective data such as reported visits to the vet, and reported veterinary assessment of pet health, were also included. 

Furthermore, in their 2024 follow-up study of health outcomes in 2,536 dogs, Knight et al. actually studied the consistency of guardian opinions with reported veterinary assessments. These proved to be very similar, although guardians were slightly likelier to consider their dogs to be healthy. Overall, 74.9 percent of guardians agreed with reported veterinary assessments, but 15.2 percent felt their dog was healthier, and 9.9 percent felt their dog was less healthy. For the 1,369 cats they also studied, 74.9 percent of guardians also agreed with reported veterinary assessments. However, 12.8 percent felt their cat was healthier, and 12.3 percent felt their cat was less healthy than the reported assessments of their veterinarians.

Respondent profile and sample sizes

Lowe argues that the fact that vegans are overrepresented in respondent profiles is a source of potential bias. But she also argues that the sample sizes for animals on vegan diets is too small. Since animals on vegan diets mostly have vegan guardians, these two points contradict each other: she is claiming that the percentage of respondents who are vegan is both too large and too small at the same time. 

In reality, what matters more here is the quality of the statistical analysis and whether the results are supported statistically. 

Statistical significance is only one part of the picture 

Lowe cautions against the conclusion that cats can experience health benefits on a vegan diet because the findings in this survey-based cat study aren’t statistically significant (as denoted by a ‘p-value’ below 0.05). But this is not the only statistical metric of importance. The study’s statistical analysis was consistent with state of the art statistical practice and the position of the American Statistical Association on the relevance of p-values, which considers the effect size (in this case, the size of the effect of the vegan diet) to be more important. Effect sizes were moderate to large in the majority of cases. For most general indicators of health, cats on vegan diets accordingly had a “tendency” or a “strong tendency” to have a lower odds of illness occurring compared to cats on meat-based diets, supporting the conclusions that “cats fed vegan diets tended to be healthier than cats fed meat-based diets. This trend was clear and consistent.” For more information on p-values, click here.

Does it matter that these cats lived mostly indoors? 

Lowe argues that, because most of the vegan cats were “indoor cats”, they are less likely than outdoor cats to visit the vet (since outdoor cats may sustain more injuries when exploring). However, this neglects the fact that the cat’s primary location was controlled for during the statistical analysis. Indeed, Lowe makes the same critique for the age of vegan cats, who were on average nearly two years younger than cats on meat-based diets, despite the fact that this was controlled for too. This was made clear in the abstract of the paper and elsewhere. 

Also made clear was the point that these cats were not fed these diets exclusively. 41 percent received a variety of treats daily, and 13 percent were regularly offered dietary supplements. Additionally, 42 percent overall (33 percent of vegan cats) had significant outdoor access. The authors noted: “It is possible that some cats, especially those in the latter groups, may have supplemented their diets by hunting. Accordingly, it is important to note that our results indicate health outcomes when cats are fed these diet types within normal households, with normal feeding regimes, rather than when cats are exclusively fed each of the two main diet types, as might occur within a controlled study within a research institute.”

Do dogs fed vegan diets visit vets less frequently? 

Lowe attempts to critique the 2022 study’s conclusion that guardians who feed raw-meat based diets to their dogs are less likely to visit the vet not because their dogs are necessarily healthier, but also because most vets oppose raw meat diets. She argues that, if the researchers acknowledge this, they should acknowledge the same phenomenon for the guardians that feed vegan diets. 

In fact, dogs fed vegan diets were the most likely of any group to be neutered, signifying a strong adherence to veterinary advice, in contrast to guardians feeding a raw-meat based diet, whose dogs were least likely to be neutered. This appears to indicate that guardians feeding vegan diets are more likely to follow veterinary advice and to visit veterinary clinics.

Unfounded health concerns about legume protein diets 

Lowe briefly refers to the occurrence of a health condition called dilated cardiomyopathy (DCM) that has been claimed to occur more frequently in grain-free and legume-based dog foods. Little detail beyond this is given, although it is important to state that multiple studies have not found any link between the use of plant-based diets for dogs and DCM. Indeed, in 2022 the United States Food and Drug Administration, which originally suggested the possibility of this link, dropped all research on this question, having not found enough reliable evidence to continue. 

Vegan diets for dogs and cats: the evidence-based position

All good scientific studies acknowledge and mitigate their limitations. In focusing so closely on the limitations of just two out of the 14 studies by late 2024 that had demonstrated health benefits for cats and dogs on vegan diets, Lowe missed the broader, more relevant trends in the research. 

By late 2024 there were 11 studies on the health impacts of vegan diets for dogs and three for cats, all of which demonstrated similar or superior health outcomes for animals fed vegan diets. Only one additional credible study (in dogs) did not support the conclusion that dogs can be healthy on vegan diets, and it is notable that this was the oldest study, with the smallest sample size. 

While any individual scientific study can usually be critiqued, the weight of evidence is clearly in the favour of nutritionally-sound vegan pet food. And while Lowe’s concern for companion animal health is reasonable, her dismissal of the accumulated evidence in this field is not. In the face of this evidence, dismissing the conclusion that nutritionally-sound vegan diets for dogs and cats are a healthy and sustainable option has now become uninformed, irrational, and unscientific. 

If you want to follow along with Dr Andrew Knights’s work on plant-based food for companion animals, please visit the campaign site here. 

*While the English language typically refers to multiple fishes as “fish,” we use “fishes” to emphasize their individuality

Read more: Vegan Diets Reduce Aggression And Gut Issues In Dogs, Study Suggests

This article was written by Billy Nicholles on the PBN Website.