Should sustainable pet diets be a leading EA cause area?

By Andrew Knight @ 2026-03-02T15:36 (+2)

I’ve recently published a study demonstrating that sustainable pet diets (those based on vegan ingredients or cultivated meat) should be a leading EA cause area. This has attracted attention in a recent EA Forum post as well as international press coverage (e.g., AP News). In the following I briefly discuss this study and the prior studies it built upon, and address some recent EA Forum comments relating to it.

Context

Nutritionally sound vegan pet diets are now relatively widely available from online vendors (e.g., www.sustainablepetfood.info/suppliers/), and are starting to be supplemented with cultivated meat-based pet diets, although the latter are minimally available so far. I’m a veterinary professor with a PhD in vegan pet diets, and an animal, environmental and EA advocate. My collaborators and I have published around 1/3 of the research in this field. Almost all of this research concerns vegan pet diets. Numerous studies have indicated good health outcomes when vegan pet diets are fed (www.sustainablepetfood.info > Health), but they do need to be well manufactured to be nutritionally sound.

Recent studies

My recent, 2026 study is ‘Sustainable Pet Diets: A Leading Effective Altruism Issue’. This built upon previous studies. In 2017, Okin considered the dietary energy requirements of dogs, cats and humans within the US, and the proportion of dietary energy within each group that was supplied by animal-based ingredients. He calculated that, within the US, 25-30% of the environmental impacts of animal farming were due to pet diets. Several similar studies described within the Discussion of my 2023 study also demonstrated major environmental and farmed animal impacts associated with pet diets. Since then a small number of additional studies have been published, demonstrating the same thing (e.g., Brociek and Gardner (2025)).

However, Okin et al. generally did not consider the effect of the partial use of animal byproducts (ABPs) within pet food. My 2023 study extended this work by doing so. Another advancement came through the recent publication of an industry report giving detailed information about the ingredients used within pet food, on a very large scale. Previously such information had not been publicly available. For the first time I was able to consider the ingredients used, their impacts, and the alternative ingredients and impacts if vegan pet diets had been used instead. This enabled me to calculate the savings in farmed animal lives and environmental impacts, if conventional pet diets were replaced with nutritionally sound vegan diets. The results are summarised in a short video and infographic.

They potential benefits are exceedingly large. For example, if all the world pet dogs transitioned onto nutritionally sound vegan diets, at least six billion farmed land animals would be spared from slaughter annually. Greenhouse gases equivalent to 1.5 times those produced annually by the UK would be spared, and sufficient food energy could be saved to feed 450 million people – the population of the EU. In fact, for several reasons described in the relevant study these results are actually very conservative. The true benefits are likely substantially larger.

My 2026 study further extended this work. After considering the average lifespans of dogs, cats and people, I was able to calculate that globally on average each year, 13 farmed land animals are consumed within the diets of dogs, compared to 9 for people and 3 for cats (see Table 2). This is partly because the diets of dogs and cats are normally comprised of a much higher proportion of animal-based ingredients than those of people. Hence, on average, more farmed animals are spared from slaughter annually, and more environmental benefits are realised, by transitioning an average dog onto a nutritionally sound vegan diet, than an average person. This is paradigm-shifting, as the animal advocacy movement has until now focused nearly all of its diet-change efforts on human dietary change. However, more good is achieved each year by transitioning an average dog onto a nutritionally sound vegan diet.

It should be noted that individual countries may differ from global averages. The US, for example, has much higher consumption of animal-based ingredients among all groups, and in the US humans consume slightly more (24) farmed land animals annually, than average dogs (20). 

Furthermore, these calculations derive from 2018 consumption levels. These have since increased significantly across all diet groups, and all of these numbers are probably even higher today. Dog populations are growing faster than those of humans, and the disparity between average dog and human consumption levels is likely even larger today.

My 2026 study also calculated the numbers of pet carers realistically likely to transition their dogs or cats onto vegan diets. These exceeded 150 million. This used data from the largest surveys of pet carers published to date, which included thousands of respondents. However, the calculations conservatively assumed only one dog or cat per household. Given that many households have more than one pet, the true number of pet carers realistically likely to transition their dogs or cats is probably substantially higher. 

These surveys also indicated the top concerns of pet carers about vegan pet diets (health outcomes, diet nutritional soundness and quality, palatability and environmental sustainability). A sizeable body of published studies have now satisfied these concerns (www.sustainablepetfood.info > various tabs), and more are forthcoming.

Despite their potential benefits, however, sustainable pet diets have attracted very little resourcing, and the sector has only two fulltime researchers/advocates, outside of pet food companies. My study therefore concludes that this issue is one of the most potentially beneficial, yet neglected, fields within the animal advocacy and environmental movements, and should be a leading EA cause area.

EA forum comments

Some recent EA forum comments have revealed certain misunderstandings about the studies above:

• The case is overstated and it’s not true that a full global transition to nutritionally sound vegan diets for dogs and cats would spare around 7 billion land animals each year

This is incorrect. In fact, these numbers are very conservative, and the true benefits achievable through a global transition to nutritionally sound vegan pet diets are probably significantly greater. There are multiple reasons for this, which are discussed in my 2023 Study under 'Limitations'. Major ones include:

• Only pet dogs and cats were included. Free-living, community owned, colony, animal shelter and working dogs and cats were excluded, however many of these are also fed pet food. If these populations were included, dog numbers for example could roughly double, with a corresponding increase in the farmed animal numbers they consume.
• Average dietary energy requirements for cats and dogs were used, but maximal requirements for people were used. This inflated human requirements relative to those of dogs and cats. If average requirements were also applied to people, their relative consumption of farmed animals would fall, and those consumed by pets would rise.

Furthermore, these figures are derived from 2018 consumption levels. As noted above, since 2018 animal product consumption has increased significantly across all diet groups (dogs, cats, humans), and these numbers would be even higher today. 

• The calculations double-count a lot of livestock carcasses

This commentator bases this position on the fact that pet food is partly comprised of ABPs, and most ABPs come from carcasses of animals killed to feed people. The commentator assumes that the pet food calculations include these carcasses, as well as carcasses of animals killed to produce the meat used in pet food. The commentator states that this double-counts carcasses.

This profoundly misrepresents the actual calculations used, and is markedly incorrect. These calculations are provided in my 2023 Study under 'Average livestock numbers (L) required to supply HC and NHC dietary fractions, for dogs, cats and people'.

In fact, the calculations effectively assign only proportions of carcasses, rather than full carcasses, to both pets and people. For people, only the human-consumable (i.e., meat) proportions are assigned. For pets, part of their consumption is meat, and part is ABPs. The carcass proportions suppling each component are used in the calculations, rather than full carcasses. Those proportions are then added, to determine the total ‘average carcass’ numbers consumed by pets and people. In this way, overconsumption or ‘double-counting’ is avoided. The results then accurately calculate the relative numbers of carcasses consumed by dogs, cats and humans. This commentator appears not to understand the details of the calculations used, and is substantially misrepresenting their implications.

The commentator also assumes the drivers of farmed animal production and slaughter are relevant to the calculations, and that the calculations are wrong because ABPs do not primarily drive farmed animal production. This position is also incorrect. The calculations make no assumptions about which factors or components drive farmed animal production. These factors are, in fact, not relevant to the calculations. The calculations rely solely on knowledge of the actual farmed animal species used within pet food, and the actual proportions of those carcasses that supply the meat and ABPs used, and the total average carcasses that are actually required. These are actualities, determined by physical realities relating to pet food ingredients, carcass proportions, and (simple) mathematics. They’re unaffected by drivers of production.

• The studies don’t engage with the rest of the literature

This claim is also dramatically incorrect. My 2026 study engages with a range of relevant literature, and cites 75 sources. My 2023 Study discusses the other relevant studies in the field in detail, under 'Consistency with prior studies'.

• Tractability is low

This is another incorrect claim. Tractability is addressed in my 2026 study under 'Tractability'. Based on surveys of thousands of pet carers, the study calculates that at least 150 million dogs and cats worldwide could be transitioned onto nutritionally sound vegan diets. However, this assumes only a single dog or cat per household. In fact, many households have more than one, and so the true numbers of dogs and cats who could be transitioned are substantially higher. Furthermore, conservative percentages of pet carers open to vegan diets were used, which were far lower than those reported in another large-scale survey discussed within this section. Additionally, awareness of vegan pet diets is likely to be much higher today than when these surveys were conducted (before 2019, and in 2020).

•  Shifting from byproducts to meat increases demand for slaughtered animals.

The studies do not significantly explore demand. What they show, irrefutably, is that more carcasses are required to produce the same quantity of ingredients when ABPs are used, compared to meat, because ABPs comprise a (much) lower proportion of average farmed animal carcasses used in pet food. This is simple mathematics.

• The economic modelling provided by Alexander et al. (2020) and others is not only accurate, but “the best thing [a commentator] could find on the subject”

The Alexander et al. (2020) study is discussed in some detail in my 2023 Study under 'Consistency with prior studies'. Alexander et al. (2020) used an economic valuation to consider the impacts of ABPs, thereby substantially underestimating their environmental impacts, because ABPs have low economic value. As demonstrated in my 2023 Study and noted above, however, ABPs require more, not less, average farmed animal carcasses, to produce. This creates more, not less, environmental impacts.

The Alexander et al. (2020) results were also impacted by other substantial underestimations and uncertainties. These are also discussed at the location above.

• dogs and cats are facultative and strict carnivores [in Spanish]

This is true but is not relevant. This commentator appears unaware that most pet food consumed is dry kibble, which comprises nearly 50% plant-based ingredients. What dogs and cats require biologically, is a diet that is adequately palatable (so they’re motivated to consume it), digestible (so it can be absorbed and reach the tissues via the bloodstream), and nutritionally sound. Modern commercial vegan pet diets generally meet these requirements, sometimes performing even better than meat-based diets. E.g. see Knight and Light (2021), and Brociek et al. (2025). 

• it is speciesist to try to focus the debate on dietary change on non-human animals rather than human animals, where we shift the responsibility for harm to other species and not our own [in Spanish]

In fact, it is speciesist to seriously harm and kill other animal species for relatively trivial reasons, such as dietary preferences, given that it is possible for dogs, cats and humans to be healthily maintained on nutritionally sound vegan diets. Transitioning dogs, cats and humans onto nutritionally sound vegan diets would all spare substantial numbers of farmed animals from slaughter, and would create substantial environmental benefits. Based on 2018 consumption levels, the annual consumption of farmed land animals in the diets of average individuals, was: dogs—13, people—9, cats—3 (2026 study> Table 2). Hence we should generally focus on dog consumption, ahead of that of people.

Conclusions

Based on the evidence, sustainable pet diets should be a leading EA cause area. A large-scale transition to nutritionally sound vegan pet diets (and those based on cultivated meat, when these become readily available), would potentially spare billions of farmed animals from slaughter annually, deliver major environmental benefits, and would even benefit pet health in certain ways. Pet carers would also benefit financially and emotionally from the latter.

Strong claims such as ‘The case is overstated’ and ‘The calculations double-count a lot of livestock carcasses’ appear to have resulted from those commentators not having read the relevant studies with sufficient care, or from failing to understand the mathematics of the calculations, or their implications. These incorrect claims undermine the case for sustainable pet diets. Similar attempts to defend the status quo were made, and are being made, by those seeking to undermine the science demonstrating the adverse effects of smoking, and the consumption of animal products, and of fossil fuels. However, these claims are incorrect, and sometimes profoundly so.

Unfortunately, due to a very heavy animal advocacy workload, I don't normally have time to follow or contribute to discussion fora. However, if any reader is genuinely struggling to understand any point within the relevant studies or calculations, rather than simply seeking to undermine these studies, then I’ll do my best to explain the relevant points. Such readers are welcome to contact me.