New paper on plant-based diets for companion dogs and cats: Sustainable Pet Diets: A Leading Effective Altruism Issue.
The paper argues that transitioning companion dogs and cats to plant-based diets is:
- Important – a full global transition would apparently spare around 7 billion land animals each year (and reduce environmental harm, and improve food security).
- Tractable – 13 to 19% of guardians are open to plant-based diets for their dogs/cats if their concerns are addressed, according to two recent surveys.
- Neglected – annual global funding for tranisitioning companion animals to plant-based diets is well below $1m.
If the numbers hold up, the case seems strong! But I'm curious about the counterfactual impact of transitioning companion cats and dogs to plant-based diets, especially given that humans wouldn't eat or use some of the animal-derived food that companion animals are fed. What do people think about that, and how do the numbers and arguments look in general?
[Edit: Andrew has responded to several commenters in a new Forum post. His post made me realise I was misrepresenting his methodology here, so I've struck those parts. I still disagree with his point about scale, but I've found a better way to express it here.]
Thanks for sharing, Alistair! I recently spent some time looking into this issue, and I don’t think it’s a good EA cause area. Pet food does directly result in the farming of more livestock that I had expected, but Knight overstates his case and doesn’t engage with the rest of the literature.
On scale:
This is not true. The paper linked doesn’t explain Knight’s methodology, but if you click through to Knight (2023) you’ll
find that the author double-counts a lot of livestock carcasses.Copy-pasting my earlier notes because I’m dashing this comment off, hope it makes sense:[Edit: I think it was inaccurate to call this double counting. My criticism is mostly about the economics of by-products, and I think I've expressed it better here].
The byproducts point is important to appreciate whether, setting the numbers aside, vegan pet food would counter factually reduce the number of animals being farmed. Knight claims that there are other economically productive uses for byproducts; if that’s true, then a reduction in demand for animal-derived pet food would change the marginal use case for byproducts but not reduce their production. That undercuts Knight’s point on scale because so much of the scale falls out of inflated byproduct numbers.
On tractability:
I haven’t dug into the surveys that Knight cites but I’m super skeptical. I know vegans who don’t have vegan pets, and I know how hard it is to make people go vegan. There are big barriers to getting humans to transition to alternative proteins at scale, and that’s only more true for companion animals.
On whether this is EA:
I’m super pleased that some people have looked into this, and I think being able to entertain weird ideas seriously is a great thing. I even think there could be some cool stuff in this space (campaigning for cats and dogs to eat less chicken and fish?).
But to be an EA issue — especially a ‘leading’ issue — it has to be more cost-effective than other good opportunities, and I don’t think it is.
I agree, Ben, that tractability is low. I am also a bit skeptical of anything saying cats can be vegan without a lot of qualifications.
However I did a bit of research into the "how many animals are actually killed for dog food" in 2023 and I got to about 3 billion/year using a bunch of approximations (Towards non-meat diets for domesticated dogs). So that's not 6 billion but it's still a lot. And I'm also just talking about dogs.
I also think that ABPs, if they didn't go into dog food, would just go into something else. I think it is a mistake to think that demand for ABPs does not drive demand for meat. The "byproduct" designation is convenient when distinguishing animal parts of different value, but at the end of the day, if you're paying someone for animal parts, you're paying them to slaughter animals. Here's a little bit I wrote about this for an op-ed I never published:
The Alexander et al. (2020) paper was about the best thing I could find on the subject in general.
Thanks Seth (good to hear from you)!
I agree with everything here. In particular: a lot of animals are farmed directly for pets, and ~3 billion sounds like a reasonable guess (I think Knight is double counting with ~7 billion). This was an update for me when I looked into this because I had thought almost all pet food was byproducts.
And I might be understating the scale case because I’m bugged by the methodology. But I don’t think the scale case is compelling when we think in terms of animals who could reasonably be taken out of the food system by vegan pet food, instead of number of animals farmed for pet food. This is something that motivates my (stray) thought that promoting beef > chicken/fish for companion animals could be high impact.
I like the Alexander paper but I think economic allocation makes more sense when you’re trying to attribute environmental harms than when you’re trying to reason about the number of animals killed in a counter factual scenario. Looking at the tools from LCA, I’d like to see somebody try a system expansion model here!
Please share the draft with me, I’d like to read it!
Thanks Ben and Seth for these thoughts, and Alistair for this post!
On scale —
I've also recently realised that the scale as presented in Knight (2023) is inflated based on his ABP calcsit's also my opinion, based on similar arguments to Ben's, that the scale of this cause area is probably lower than Andrew suggests. [Based on Andrew's response, I've rephrased the above sentence]. However, it's worth remembering that ABP use in pet food is a declining trend, at least in the US. Premiumisation has already pushed animal-based ingredient use in pet food to have a roughly 50/50 split of ABP vs human consumable ingredients. And the ABP proportion is declining further -- I'll be publishing updated data on this in the next few months hopefully.On tractability, I agree more with @Denkenberger🔸 that there's more potential here than most people are assuming. Compared to humans, where taste/texture replication is v important and v difficult, and diet habits change regularly, it's much easier to create palatable plant-based diets, and to keep dogs on exactly the same diet for a long period of time.
It may well be that transitioning dogs to plant-based diets is easier than for humans. The key is how they're marketed -- as in the human space, labelling the food as "vegan dog food" will badly damage uptake, but marketing as "hypoallergenic"/"clean"/"sensitive diet" can be more effective (see Omni, the UK's leading plant-based dog food company, which is v quiet on vegan messaging, but is growing in mainstream appeal).
I'd also point those interested towards a new study (co-authored by Peter Alexander) by Harvey et al. (2026), which compares different ABP allocation methods. Their range for global impacts of dog food consumption is 469-1332Mt CO2eq annually. Knight's 2023 estimate was 759Mt. So, while v likely still an overestimate, it's roughly in range of this study too, which I think was well conducted (the lower range is using economic allocation, the higher fig is using a form of mass allocation that definitely overestimates impacts).
I'm interested in looking more into the marginal impact of ABPs in pet food (e.g. via system expansion modelling), and am interested to chat this through with anyone who has thoughts on this!
[Edit: I make a further case for tractability on another post on this topic here. Would encourage those sceptical of vegan pet diets on tractability grounds to read!]
re: "the scale as presented in Knight (2023) is inflated based on his ABP calcs"
Readers should be aware that this is an unsubstantiated claim. My recent post has more information on this topic.
Intersting previous post! I think your caculations work similary assuming 100% of the demand for meat in pet food translates to farmed animals. The effect of a decrease in demand for ABPs on the number of farmed animals will be less than 1-1. Based on the Peter Alexander paper that would suggest a 45% to 63% discount on the contribution. (Which brings your number down to more like 1-2 billion, still alot in absolute terms). Although even then its more of a simplifying assumption as the real decrease would depend on counterfactual uses and how shifts in demand and prices eventual wash out. You also don't include fish or developments for insects that could boost the numbers back up the other way.
Although I don't think total numbers is main crux. Importance or neglectedness are only really good proxies for wether to look into an area which I think the case for vegan pet food has done fairly well.
Tractablity is very important. If we survey humans similary for are they open to plant-based diets we get a similar high or higher number, "38% of German and UK adults intend to change their diets by eating more plant-based foods". Broad intentions are not a great indicaiton of how cost-effective interventions to talk with pet owners, pet food companies or goverments to transition would be. For 1-1 outreach I'd expect targeting pet owners to be less effective than vegan outreach just for the fact that 2/3 of people won't be relevant.
I think more informative direction for future research in this area would be to do target research and some inital conversations and testing. I'd want to see that:
1. companies are shifting a large enough volume of product (when discounted for the ABP effect on overall demand for animal farming) that targeting this could plausibly be worthwhile
2. work with Pet food companies, retailers or other institutions to shift proportions of ingredients in food to be more plant-based for better animal welfare and climate outcomes seems tractable as a campaign. Thinking why they would do this? Would people support action against them if they don't? Are there other incentives we could use?
3. It does not backfire. We would have to watch out the small animal replacement problem if they shift to chicken or fish for climate reasons.
Maybe there are potential cost-effective campaign targets but high meat proportion is usually a selling point for pet feeds. At the moment i'd expect running a campaign like that would be more difficult relative to how important the campaign target is compared to the marginal cage-free or broiler campaign.
re: "I am also a bit skeptical of anything saying cats can be vegan..."
This is a common concern by those new to this issue. These can help:
https://sustainablepetfood.info/faqs/, https://sustainablepetfood.info/vegetarian-feline-diets/#3.
Pets (and people) need nutrients, not ingredients. They require a nutritionally sound diet. They do not require meat.
Some of the other comments I address in my recent post.
I'm skeptical as well, but in some ways, the barriers for pets going vegan are lower:
In the last few decades, dog food has become more plant based because plants are cheaper (and they figured out how to make it appealing to dogs and not offensive to people). If methane SCP can become cheaper than animal byproducts, you could have a healthy cheaper product with lower environmental impact that probably wouldn't taste as good, but I think many non-vegans would go for.
Do you have any research on the increase of plant- vs animal proteins? Trend watchers and insideres see an increase of proteins (mainly animal based).
I believe there is already value in doing this assessment for pet food market similar to The Protein Tracker.
I just have info from AI:
Unless there are links I wouldn't take these stats as gospel
By the way, Ben
I don't think "not reduce their production" follows from your reasoning. If the next available use cases pay less money, we should, in espectation, see fewer animals raised, no?
I think you're right in a theoretical marketplace: there is a demand signal here and we should expect production to decrease slightly.
I don't know that this stretches to the real marketplace. For one, it turns on how much less the next available use case is willing to pay, and historically it looks like the rendering industry has done well to find substitute uses (e.g., when synthetic soaps took off). I asked Perplexity, so fact-check this, but it suggests that slaughterhouses sell human-grade chicken for about $1.15 to $1.25 per lb, and they'd lose about $0.02 per lb on their by-product profits (<2% of the profit margin from their main product) if they switched from selling to pet food manufacturers to selling to pork farmers.
For another, I think animals are lumpy good. Selling by-products does slightly increase the profit margin, but it's a thin part of the overall profit margin, and I don't know if losing that valorisation stream really shifts the economics for the farmer.
Relatedly, you say
I definitely see your point, but I wonder if there's another sense where: biological waste is a ticking time bomb. It will smell and start to attract vermin and disease. From the slaughterhouses' perspective, it's amazing that somebody will pay to come in quickly and take that away. But the slaughterhouses would still swallow the cost, and probably not seriously consider killing fewer animals, if they had to dispose of that waste themselves.
Just thought I'd share a reference that may be useful when quantifying the animal welfare impact of pet food - it quantifies environmental impacts taking into account the effect of pet food purchases incentivising keeping more livestock, and it seems to me like a similar approach could be used to quantify animal welfare impacts.
Alexander et al., 2020, "The global environmental paw print of pet food", Global Environmental Change, 65, 102153, https://doi.org/10.1016/j.gloenvcha.2020.102153 . Here's a free-to-access version: https://drive.google.com/file/d/17dpVo9QByHpe0NxyHUiR2VfYRnhLs71X/view
That study has several substantial flaws discussed in my 2023 study. It substantially underestimates the environmental impacts of pet food. This is partly discussed in my recent post.
First of all thanks @Alistair Stewart for bringing this subject and research to the EA Forum and interesting discussion above. Over the past few months I dug into this cause area and talked to dozens of experts (NL and EU). In summary my conclusion is yes EA should spend more resources on this cause area. In summary:
The scale is very large, yet probably not as high as mentioned in some articles, as @Ben Stevenson also pointed out. The pet food market expected to grow more than 5% CAGR during 2025-2032 as economy grows and human birth rates decline. In China the pet food industry is growing even more rapidly. Next to this, there is a clear trend of humanization of pets. In which we only want ‘the best’ for our companion animals and are willing to pay premium, which results in high quality human-grade meat (non by-product) and following the protein hypes, increasing demand.
There is limited mentioning here in the comments for fish and insects. Research estimated that the average household cat in Australia eats more fish than the average Australian citizen. Again these numbers can be on the high end, yet it’s evident that the cat food industry drives demand for fish. Especially considering that bycatch is often not deemed suitable for humane consumption ends up in pet food, leaving little incentive for fisheries to improve their methods.
As the insect market is declining for human food due to limited economic viability. However, the insect industry larger customers are mostly in the (pet) animal feed industry. Given that animal welfare is an EA cause area there is a strong link with pet food as well. As insect proteins are considered as a reliable protein ingredient for primarily veterinarian diets.
High level of neglectedness, pet guardians are unaware of the ecological and animal welfare footprint of their companion animals and meat is considered the norm. There is little knowledge among pet guardians on animal-free alternatives and misconceptions on health implications.
In terms of animal welfare standards, I have talked to several (European) animal welfare organizations and none of them had pet food in their (current) scope. Walk into a regular petfood store and check the packaging for any mentionings of animal welfare standards and you will notice that these are missing. The supply chain of ingredients is not transparent as some already pointed out the pet food is based mainly on animal by-products and controlling institutions have already limited bandwidth to monitor human food industry for welfare standards. I believe it can already be a quick win by targeting the largest pet food brands and drive for improved welfare standards. Recently the French organization L214 issued a campaign against Hill’s on their broiler chicken standards.
Tractable, balanced healthy plant-based alternatives are available for adult dogs and both clinical research, as large pet guardian population surveys have shown that these are considered healthy. However, I don’t think it’s realistic that dogs and cats will move quicker to a solely animal-free diet than humans. Therefore I would argue for a flexitarian strategy reducing animal-based proteins as much as possible. As @Denkenberger🔸 also pointed out most pets eat the same food every day.
Lastly, I would like to bring @Karthik Sekar’s previous EA Forum discussion on this subject to everyone’s attention where several promising pathways for cats are summarized: Getting Cats Vegan is Possible and Imperative — EA Forum
In line with @George Bridgewater's 2nd strategy to discuss with major a shift to more plant-based proteins in pet food formulation, I'm in the middle of starting an NGO that applies this theory of change and accelerates alternatives.
If you want to contribute to accelerating alt proteins in pet food feel free to reach out. Currently mainly focused in The Netherlands and Belgium.
Importance and neglect aside, I am skeptical of the tractability. The 13 to 19% is interesting, but I have doubts that translates to a significant amount of real-world behavior. It seems like you almost need to be vegan to be motivated enough to make your cat/dog vegan.
Would refer to my comment above here. It's definitely not the case that you need to be vegan to be motivated enough to make your cat/dog vegan -- many non-vegan guardians are drawn to plant-based diets (knowingly or not, depending on the marketing) motivated by health, allergies, or environmental concerns.
As a lay person, this topic sounds nutty. It may be useful to maintain whatever the equivalent of self-awareness is, for those that might be uninitiated and considering identifying with the group.
Personally, I don't think "mostly or entirely plant-based diet for dogs" sounds nutty. I think most people understand that dogs can subsist on literal garbage. Might not be optimal but I think we can make the case that if you feel really strongly about supplementing a healthy plant-based diet with animal protein, it should come from bivalves.
The case for cats is much less intuitive, I think.
Thanks for this Nick -- you're right that this topic can seem absurd to some people at first glance, and i've seen this quite regularly with comments on mainstream media reports.
I don't think this has to be the case though. The phrase "vegan pet food" can sound like (contraversial) human ideals forced on helpless companion animals, but that's quite clearly not the actual motivation here (and I now think not the phrase we should be using externally). Framing and marketing the debate/products around the principle of responsibly feeding companion animals while ensuring with good animal welfare standards, sustainable production, and optimal pet health is possible. I think many would agree that this is a reasonable goal, and that change is reasonable if the status quo isn't meeting those parameters.
If any good marketers have more thoughts on how we can package and communicate this case to pet owners, I'm keen to hear them! E.g. @Kempe
Creo que no tenemos presente que los perros y gatos son carnívoros facultativos y estrictos, respectivamentem, en primer lugar. Además, es altamente especista tratar de centrar el debate del cambio alimentario en animales no humanos y no en los animales humanos, donde cambiamos la responsabilidad del daño a otras especies y no la nuestra. No me referiré a más puntos de forma técnica porque Ben los ha abordado de buena forma, plegándome a lo que él ya ha mencionado.
This is addressed in my recent post.