Summary

• Carnivore is a classification, not a diet requirement.
• The amount of meat that cats eat is significant. Transitioning domestic cats to eating vegan would do much good for the environment and animal welfare.
• Having vegan cats now is not convenient, but we (humanity) should make that so.
• We do not need to wait around for cultivated meat. There are tractable opportunities now.
• We also need randomized control trials with measured health outcomes; funding is the main limitation here.
• Making domestic cats vegan meets all of the Effective Altruism criteria: significant, tractable, and neglected.

Main

Imagine you are a surveyor traveling to remote parts of the world. Within a thick rainforest, you come across an indigenous group long separated from the modern world. They fashion spears to hunt fish and thicket baskets to collect foraged berries. Notably, they wear distinctive yellow loincloths dyed with local fruit. You are not one with words, so you call them the Yellowclothea. 

This is not a farfetched story. Most species worldwide are classified similarly–someone observes them and then contrives a classification named on what they see. Carnivora was coined in 1821 to describe an Order of animals by the observation that they consumed the meat of other animals–carnem vorāre is Latin for “to eat flesh”. 

Let us go back to the Yellowclothea. You can already intuit that these natives do not have to wear the yellow loincloths–it is simply what you initially observed. If the natives swapped the dye with purple or green, that would work out fine. However, the rainforest lacks those colors, so Yellowclothea is resigned to their monotone. In other words, wearing yellow cloth is not a requirement for them to live, just what works for them and is available. 

1821, the year of Carnivora’s naming, is ages ago in the scientific world. It was before the Theory of Evolution, first described in The Origin of Species in 1859. It was before the molecular biology revolution. It was before we understood the basis of metabolism and nutrition. So it is easy to confuse classification/observation with the requirement. It is the same fallacy as assuming that the Yellowclothea people can only wear yellow clothing. 

Since 1821, we learned more about nutrition, molecular biology, and metabolism to demystify meat. Meat is mostly muscle fibers with some marbled fat and critical nutrients. Carnivora animals generally have more acidic stomachs and shorter gastrointestinal (GI) tracts than nominal herbivores. The extra acid helps chop proteins into the alphabet amino acid molecules, which are readily taken up, so a long GI tract is unnecessary.

So Carnivora animals cannot have salads or raw vegetables, which are rich in fiber and would not break down in their GI tracts in time. Nevertheless, we can make protein-rich and highly digestible foods for Carnivora starting from plant and microbial ingredients. Just as a cow will chemically process the plants into their muscle–flesh, we can similarly turn the plants into food that a carnivore would thrive off without an animal intermediary. In other words, we can source all the required nutrients from elsewhere, without meat. 

There is—at least in theory—no reason why diets comprised entirely of plants, minerals, and synthetically-based ingredients (i.e., vegan diets) cannot meet the necessary palatability, bioavailability, and nutritional requirements of cats

Andrew Knight, Director, Centre for Animal Welfare, University of Winchester

I have written about how succeeding meat, dairy, and eggs with plant and microbial-based alternatives will be one of the best things we ever do–I argue that it is better than curing cancer or transitioning fully to renewable energy. Provided that we continue to innovate, we will complete this transition, and we should not just replace the meat that humans eat; we should replace the meat that cats eat too.

Making cats vegan has been contentious, even among vegans. I have read highly upvoted comments on popular vegan forums r/vegan and r/debateavegan “conceding” that cats are carnivores, so we should continue feeding them meat and just advocate veganism to people. This notion is fallacious and relies on a chain of appeals to authority without an eventual biochemical basis. We can render meat unnecessary for cats, and we should absolutely strive toward this reality for all domestic cats.

Cats eat a sizable amount of meat and replacing the quantity is significant. I estimate that we feed domestic cats about 3 billion kilograms of meat per year in the United States. This quantity is about the same amount of meat as the entire population of Canada consumes.¹ Replacing even a fraction of meat consumption has a sizeable impact–a study last year estimated that replacing a mere 20% of beef with microbial protein would halve the rate of deforestation. Therefore, replacing a significant fraction of the meat that cats consume would help prevent trees from being cut down. Moreover, getting cats to eat 20% less meat in terms of chicken in the United States would save nearly half a billion chicken a year from brutal livelihood and slaughter.² 

Cat food is also linked to human meat consumption. Cat food tends to be the offal of the animal agriculture industry. Producers repurpose meat unfit for humans into cat food. As The Clean Pet Food Revolution highlights, pet food is a vital income stream for the meat industry. Without it, meat prices would go up because margins in the animal agriculture industry are thin. In other words, the less meat that cats eat, the less that humans do too. 

In the United States, convenient retail options for vegan cat food are hard to come by. Ami, Evolution, and Benevo are the principal, nutritionally complete brands for vegan cats, but all three are not exactly available in your local Petco. Ami is persistently out of stock. Ami and Benevo are quite expensive–Benevo sells for about $16 per pound on Amazon, roughly four times more than Merrick, a mid-tier meat-based brand. 

Vegan cat owners also have more work to do. When a cat is transitioned to a vegan diet, their urine must be monitored for changes in pH. Meat-based food tends to be more acidic than vegan food, which cats are not adapted to. When a cat’s urine is too alkaline, they are prone to forming mineral crystals in their urine, which are painful to eliminate. Owners must acidify their cat’s food as needed. (EDIT: Researcher Andrew Knight brought to my attention that this is not shown to be an increased risk with vegan food fed to cats. Please see here.)

Nonetheless, studies have supported rearing cats on a vegan diet healthily, and we likely have capabilities now to make this more seamless. The solution here is not to wait for cultivated meat–likely still decades away–or even sophisticated alternatives like Impossible Burger. At this point, we need the tofu and soy milk.

Instead, we should get more approved ingredients for cats that enable more formulations. One limitation for approved ingredients in the United States has been testing at The Association of American Feed Control Officials (AAFCO). This non-profit organization serves as a surrogate to the Food and Drug Administration for the guidance of pet food. AAFCO regulates pet food in two key manners: (1) they approve ingredients for retail pet food and (2) set standards for nutritionally complete cat food in terms of macronutrient composition, for example, the minimum amount of protein and vitamins. 

More approved ingredients would mean more possible healthy formulations for vegan cat food. AAFCO approval can be laborious and drawn out per discussion with employees at vegan pet food companies.³ That means novel plant or microbial-based ingredients that enable better vegan cat food can take a long time to come to market. Vegan cat food companies are left to concoct recipes with limited ingredients. It is as if you are a chef with only a few ingredients in your kitchen, and you are tasked with making meals with exacting nutritional requirements. You can do it, but your job would be much easier if you had access to protein-rich kōji. If you had more ingredients at your disposal, you could make something more affordable, tastier, and less sensitive to supply chain issues.

Opportunities

I see many opportunities to help realize the vegan cat world sooner than later:

1. Funding more ingredients to be tested - More ingredients available for pet food makers would make it easier for them to make better and more varied vegan cat food formulations. Third-party funding on key ingredients would help the entire industry and reduce the entry barrier on retail vegan cat products. Ingredients should be triaged on how many recipes they open up. For example, using the chef analogy, cooking oil would enable more gastronomy than, say, asparagus. 
2. Develop a more streamlined, expedited ingredient approval process - AAFCO approval process is noted to be slow, laborious, and costly. Ultimately, the FDA and state governments are the ultimate arbiter of pet food and defer authority to AAFCO. Using other organizations, perhaps in other countries, to test pet food would set a precedent for countries with more onerous regulations.
3. Funding more formulations for testing - Pet food is a low-margin business. Most pet food is the dregs of the animal agriculture industry, material that would be disposed otherwise. Testing formulations is proportionally more costly compared to testing a new cancer-fighting drug for humans. Third-party funding would offset the costs that are difficult to recoup with sales.
4. Funding long-term studies on the health of vegan cats - Currently, most studies on the long-term health of vegan cats are observational or survey-based, meaning that the authors did not design the experimental conditions and rely on post hoc analyses or owner assessment. Ideally, we can do a Randomized Control Trial, the gold standard, on cats with various vegan and non-vegan diets and measure vitals to assess their health outcomes. Funding is dearly needed to perform these studies and would convince the many who are uncertain about feeding their cats vegan. Note that we don’t want just one long-term study. We should fund the study of many different vegan diets to find the best ones, and we should keep funding studies to find better formulations.
5. Repudiating what “obligate carnivore” means - Kindly, but stridently, we have to correct folks that obligate carnivore (EDIT) precludes the possibility of a vegan diet. This outdated thinking ignores the fundamental understanding of biochemistry, nutrition, and metabolism, which has only developed since the initial carnivore classification.
6. Advocating to vets - On a similar note, we need to evolve vet’s outdated nutritional understanding of carnivores and appeal to their better nature about helping all animals, not just companion ones. Vets are positioned well to understand the health of cats and to ensure that the owner is rearing vegan cats as well as possible.
7. Rearing vegan cats - There is enough evidence that cats can be raised vegan healthily. Since raising cats vegan continues to be pilloried and dismissed, there is an opportunity to do good here by being a leader and an example for others. Be that owner who raises their cat vegan. I have previously argued that pioneers at the start of an S-curve transition do inordinate good by “shifting the curve.”

Responding to Common Concerns

I’ve heard plenty of push back on some of the ideas, so let me respond:

1. “These diets are not natural” - The (EDIT) appeal to nature argument is wrong, outdated, and destructive. So much so that I wrote the entire first chapter of After Meat explaining why–you can read or listen to it for free here. Furthermore, the meat-based cat food on the market differs from what cats “naturally” eat. Store-bought meat is what’s unsuitable for human consumption–the scrap animal parts: livers, stomachs, etc. This meat is far from the fresh flesh that cats eat during wild hunting.
2. “These foods would be too synthetic, too processed” - Cat food already on the market is highly “synthetic”. Because store-bought cat food meat is often so diseased, it usually has to be boiled for sterilization. The poor quality meat and sterilization depletes vital nutrients such as taurine, zinc, thymine, vitamin E, vitamin A, vitamin K, copper, manganese, vitamin B12, folic acid, potassium, vitamin D, and others. These nutrients often must be supplemented back in. Secondly, I argued why “processed” is an imprecise, unhelpful adjective when discussing food. Long story short, calling a food processed will not tell us if it is healthy or unhealthy. 

Conclusion

In After Meat, I concluded we would have plant and microbial-based alternatives better than conventional animal products regarding taste, cost, and nutrition. Relying on animal technology has physical limits. It’s not just winning on ethics and the environment; alternatives can also exceed on purely selfish consumer values. In the same way, we can eventually do the same with cat food and reach a win-win.

Enabling more vegan options for cats is different from animal product alternatives for humans or dogs. First, there’s addressing the confusion about whether we can rear cats in a healthy vegan manner–we can, and funding more studies will show this demonstrably. The second issue is fostering market conditions for more vegan cat food options. The limit is regulatory, and third-party funding is sorely needed to get more ingredients tested and to defray development and approval costs for vegan pet food producers.

Notes

¹ There are about 60 million cats in the United States. The average cat is about 10 pounds and requires about 300 calories per day. It’s hard to get a figure on the percentage of meat in store bought cat food, but I estimate around 75%, so that translates to 225 calories from meat. There’s roughly 200 calories per 110 grams of meat. So each cat consumed roughly 125 grams of meat per day. For all the United States, that’s about 2.7 billion kilograms of meat per year for all the cats. Canada consumes about 85 kilograms per person per year * 37.5 million people = 3.1 billion kilograms of meat per year. 

²One chicken is roughly 1 kilogram of meat. 20% of 2.7 billion kilograms is 0.54 billion kilograms, so that’s roughly half a billion chickens.

³I discussed with employees at Wild Earth and v-dog.

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