And Neither Should Your Pet Carnivore…

It’s already halfway through January. It’s been hard to escape the “new year, new me” bandwagon and the ever more present “Veganuary” initiative to encourage us to embrace a vegan diet to improve our personal health and reduce our environmental impact.

So, it’s hardly surprising that an increasing number of vegan pet foods have arrived on the market. It’s such an easy sell: if you love animals then why should they suffer just to feed your pet? Don’t you want to minimise your carbon footprint/pawprint? The arguments in favour are beguiling and designed to appeal to pet parents. They are using our love of animals and the natural world, and our desire to do what’s best for our pet and our shared planet. But personally, as a trained biologist, I feel the vegan pet food marketing is superficial and often just plain wrong. I feel that with our current food technology, it’s not possible to feed a dog or cat a vegan diet for the longer term and be certain we aren’t damaging their health. Yes, dogs are facultative carnivores evolved to survive on whatever scavenged calories come their way, but to truly thrive they need animal protein.  You can live an otherwise vegan lifestyle but please accept that your pet carnivore needs to eat animal protein or if this isn’t acceptable to you then please consider a vegetarian pet such as a rabbit or guinea-pig. Your dog is a carnivore, please feed them as such.

Please note: for a very few dogs with complex kidney issues and/or food intolerances then there might be reasons to choose a plant-based diet short-term (under vet supervision). This isn’t about those dogs, this is about the pet dogs who are fed vegan as a lifestyle choice by their carers.

Cats and Dogs Are Carnivores

I’m going to stick to talking about dogs here because I have a dog, however the same applies to cats but more so, these are CARNIVORES (literally “meat eaters” in Latin). The clue is in their name, they need to eat animal protein. First, some comparative anatomy. If your dog or cat will let you, then open their mouths and have a look at their teeth – really pointy jagged canines evolved for holding onto and ripping through prey, that’s not the grinding dentition of an animal that eats plants. They have a short extremely acid digestive tract with no second stomach for fermentation of plant matter. They produce high levels of protein and fat digestion enzymes and low levels of starch digestion enzymes. Basically, everything about their teeth and digestive system screams meat eater. On a molecular level too, they are carnivores. All animals are made up of cells, think of them as the Lego building bricks that make up your body and your pet’s body. Little fluid filled bags that are also factories, warehouses, power stations, building sites, waste recycling plants, structural supports, and army battalions. The cells all need energy to carry out their various processes. Their energy comes from food that is broken down in the gut into smaller molecules carried in the bloodstream, then passed across cell membranes into the cells that need it. The two main energy sources are carbohydrates (all the starchy/sugary foods) that are broken into glucose to fuel an intracellular energy harnessing process called glycolysis, or fats and proteins that fuel an alternative process called ketosis. Mammals appear to be able to use either glycolysis or ketosis, but each cell can only use one method at a time and switching between is inefficient and each switch on/off releases proinflammatory messenger molecules which long term can lead to increased risk of cancers, diabetes, pancreatitis, and autoimmune conditions. So, it’s more efficient to use primarily one or the other for your main cellular energetics. Most modern humans as true omnivores mostly use glycolysis, but we can use ketosis if we eat a high fat and low carb diet. There are some dieticians who would argue that this is our more natural state, and we should eat this way, hence the popularity in some circles of “keto” and “paleo” diets. The wild relatives of our dogs and cats primarily use ketosis, and as there’s no major physiological differences between a wild canid and Sally fluffy wolf, it seems logical to assume that ketosis is her default state too, as it is for your pet carnivore. So why does this make vegan foods bad news for our dogs?

Vegan Pet Food Tends to be High Carbohydrate

So, let’s start with the nutritional bit they don’t have to put on the packaging: the carbs. Most vegan foods are dry kibbles high in carbohydrates. In many pet foods carbs make up a greater percentage of dry weight than the fats or proteins but (amazingly) pet food manufacturers don’t have to declare the carb content (unless they choose to). A small amount of complex carbs can be beneficial to dogs as prebiotic dietary starch and plant matter supplies vitamins and minerals that would otherwise be lacking in a purely animal-based diet. But despite what the food bag label might tell you carbs aren’t really a “healthy source of energy” for a carnivore. If you feed a high carb food to your dog, then they will be forced into constant switching between glycolysis and ketosis as they try to extract the energy (and as explained above this really isn’t good for them) and if there’s more energy available in the carbs proportion of their food than they require at that point in time it will get converted to glycolipids and stored as fat (extra protein and fat is more easily excreted), so feeding that carb-rich food may also encourage weight gain and obesity.

Vegan Pet Food Is Usually Low Moisture

Another issue with dry carb-heavy kibbles: water (or lack of). Dogs have evolved for tens of thousands of years eating a diet of raw, then raw and cooked scavenged foods that would be around 70% moisture. With most dog breeds not having the kidney complexity to survive desert conditions, feeding a dry diet long term is going to put strain on their urinary tract. Before/after we get into the other nutritional shortfalls of vegan food for carnivores, dry food is going to be a potential urinary tract stressor. Carnivores that have evolved to obtain most of their liquids from food don’t get strong thirst signals if their stomach is full, so they don’t know to drink extra with dry food. If you do have to feed dry food, any dry food, to your dog then always add additional water to their food-bowl and wet the food.

Plant-Based Fats Are NOT Comparable to Meat Fats

Fats (lipids) are essential for energy, and for healthy growth and tissue repair. All those cell membranes are fats, fats cushion joints, are used to build the eyes and brain, help carry fat soluble vitamins around the body and make hormones and immune messenger molecules. When allowed to self-select their food it’s been shown that dogs consume around 50% of their calorie intake from fats (Roberts et al. 2018). Interestingly this works out to 10-20% of their food by weight, curiously about the fat % they’d get from eating a raw diet based off whole prey as this is about the fat % of prey animals such as a duck or a rabbit.

There are many types of fat, dogs can use pretty much any fats found in animal or vegetable oils for ketosis. So yes, if it’s “just” for energy then dogs could use plant fats although if these are high temperature cooked, they may be inefficiently digested. They also require “essential fatty acids” (so-called because mammals can’t synthesis them for themselves) for growth and tissue repair. These are also known as omega oils, the main types being omega 3s, 6s and 9s. They are predominately synthesised by microalgae, and bioaccumulate in the marine food chain until consumed by predators. Only marine sources are an easy way to get the full range of these fats, land-plants tend to contain mostly omega 6s with a low or no omega 3s. Pet food standards (based off what’s easiest for manufacturers) allow the ratio of omega 6s to 3s to be up to 30:1, but this is far from what dogs would naturally encounter if eating animal prey, in grass-fed meat the ratio is only around 3:1. But for anyone formulating a new pet food you can bet that they’ll add omega ratios closer to 30:1 than the natural 3:1. Also in pet food, high temperature cooking can make many fats more difficult for carnivores to metabolise. They can end up developing pancreatitis as they are forced to produce extremely high levels of digestive enzymes to break down the cooked fats. In contrast, the fats in raw or lightly cooked meat are more easily digested and provide an easily obtainable energy source. It’s the difference between a flexible raw piece of pork and a dried out piece of crispy bacon. Once you dry up and cook the fats it’s increasingly difficult for the dog’s body to digest them. All vegan dog foods are high temperature cooked tins or kibbles, so making the fats inaccessible to dogs, increasing their risk of pancreatitis when they try to digest them (why you’ll see “low fat” kibble sold as if this is a good thing) and impairing their ability to synthesis hormones and maintain joints as the only omega oils provided in quantities are omega 6s. It’s just not possible to make a vegan food with a high quality (for a carnivore) lipid profile unless you use high-cost marine algal additives. If these are added they will be added sparingly to make up the minimum and not the optimum nutrition levels. So, I also won’t be feeding my dog vegan because vegan dog food doesn’t have the fat profile she needs for good health.

Vegan Protein (Or Lack Of)

Proteins are the structural (the muscle tissue etc) and the workhorse (the enzymes, antibodies, and some messenger molecules) components of cells. They are made up of links known as amino acids. There are around 20 core amino acids (we can argue about the weird tRNA modified ones later, this is a basic overview so let’s just say 20 core amino acids) in mammals. For dogs, 10 of these amino acids are considered essential -again similarly to essential fatty acids, these are essential as their bodies need but can’t make them, they need a dietary supply. Plant proteins have a very different amino acid profile to animal proteins and are low/lacking in some essential amino acids. This means absorption and use of the essential amino acids is not as efficient as from animal protein, you need to feed a higher overall amount of protein to get enough of the essential amino acids, and few/no plant sources are “complete” protein sources with all 10 essential amino acids, whereas most animal proteins are “complete” in that they contain all 10. Pet food manufacturers have a minimum recommended intake for each essential amino acid, but this is recommendation not a requirement, and it’s also again this is the bare minimum needed for survival. So, while that bag of vegan kibble may be marketed as “high protein” it is NOT high-quality protein for your carnivore, as it’s high plant protein with a different amino acid composition. To make it “complete” most will use yeast extracts. Yeast extract is a controversial dog food additive as some fresh feeding advocates feel it’s (over)use as a pet food ingredient may increase risk of grain intolerances (from trace amounts of grain protein), gut or skin yeast infections (as it’s extracted from yeast cells it’s the perfect fuel for yeast growth), and bloat (it could occasionally contain trace amounts of highly toxic ethanol – a natural waste product from the yeast, which forms excess carbon dioxide gas as the body attempts breakdown). The problem with all these claims are that they haven’t been assessed by scientific studies, so while the naysayers can give plausible sounding reasons to avoid yeast extract for our dogs, we just don’t know whether their fears are warranted. Yeast extract isn’t a particularly “natural” foodstuff for a fluffy wolf, so again I’d rather avoid, better be safe than sorry… Finally most vegan proteins, whether plant or yeast, undergo the same high temperature cooking as the fats. Again similarly to fats, this renders the protein more indigestible and less able to be used by the body and could be more likely to trigger an immune reaction.

Legumes

Legumes (soya, chickpeas, beans, peas, lentils etc) are used as to increase the protein levels in vegan pet foods, and as a filler to make the ingredients adhere together. You may be increasing your dog’s risk of developing dilated cardiomyopathy heart disease (DCM) if you routinely feed large quantities of legumes. The original working hypothesis was that the legumes interfered with absorption of the essential amino acid taurine, and this resulted in heart muscle abnormalities. The American FDA opened an investigation but failed to identify a link. It’s considerably more complex than simply that legumes result in taurine malabsorption (many dogs on legume-rich foods have normal taurine blood values) but in one experimental study feeding high legume protein grain-free foods resulted in measurable (on an echocardiogram) heart damage in as little as 30 days even although the study dogs appeared outwardly healthy (Owens et al. 2022). This is incredibly worrying for anyone thinking about switching to a vegan dog food as most use legumes. Given the possible heart disease link, and how quickly the first signs of heart disease can develop, legumes are NOT ingredients I’d want in my dog’s daily diet.

Vegan is (Wrongly) Marketed as a Premium Food

Okay, I’ve said what I don’t like about the vegan dog food ingredients, but considering that at the bottom end of the pet food market “with chicken” can legally mean the food contains only 5% chicken, is vegan kibble really any worse? The vegan alternative is likely to have higher overall protein and more natural ingredients. So why am I warning you away from the vegan dog foods?

Cheap dog food doesn’t make any pretentions, it’s cheap, it’ll fill your dog up and provide the minimum legally permissible nutrient levels that will keep them alive. Yes, it will be high carb, low protein, low moisture, and it will contain synthetic versions of vitamins and minerals that are inefficiently absorbed compared to their corresponding natural forms. But you know it’s not a premium product, so hopefully you are more likely to supplement it with additional fresh meat and fish and veggies whenever you can. The difference is that vegan dog foods are priced to compete with the luxury end of the market, but are generally low nutritional quality masquerading as gourmet offerings. They are often marketed as a complete food solution and a means to avoid the ick factor of having to feed your dog those yucky animal protein extras. Yet they are anything but luxury, and can be made with cheaply sourced ingredients bought on the global marketplace with poor traceability from farm to consumer and have to be supplemented with synthetic additives to be able to squeeze past the goalposts of being legally sellable. Yet their manufacturers use emotional blackmail that as animal lovers we will pay extra for their supposed ethical and cruelty-free advantages. They throw in some dodgy “science”: dogs are omnivores is a favourite claim, no they aren’t, dogs can be omnivorous (anyone who’s walked a puppy will know they will eat just about anything regardless of nutritional value – hello dirty tissues, lost glove, fortnight old roadkill, dropped sandwich, fox poo etc) in that they will take advantage of any calories they happen to come across, but their physiology and molecular biology are that of a true carnivore. It’s “vet approved” is another common statement- you just need to find/pay one vet to agree, it’s a meaningless utterance. Add a testimonial that “Fido had a constantly dull coat and itchy skin until they started on V-Dog Wonder Fud^TM” and you are ready for market. Yes, if a dog has a protein or grain intolerance and the vegan food omits that specific allergen, then short term problem solved, but you could just as easily feed them any other food without particular trigger. Don’t fall for clever marketing, for every pet food, read the label carefully to help you decide if it’s something you’d want to feed to your dog. Look for named traceable and fresh ingredients and low/no added synthetic nutrients.

So, If Not Vegan, Then What?

Ethics

What can we do to decrease our collective pet food carbon pawprint? What are the alternatives to vegan dog food? In the short term it’s probably best to look for companies with a focus on ethical and environmental accountability, some use B-corp certification to signal their progress. Look for ingredients sourced from regenerative agriculture, local ingredients, higher welfare farming, and genuinely renewable or recyclable packaging that works for you (it’s no use it being home-compostable if you don’t have a pet-secure compost heap, it’s no good it being recyclable if your local council doesn’t collect it). There are some companies making encouraging steps in these areas, Naturaw, Different Dog and Lily’s Kitchen have received B-corp status, Ethically Raised uses regenerative farming, Bella and Duke use only UK and Ireland sourced meat and vegetables and higher welfare farms and are part of RawSAFE that ensures higher food traceability. Many now use food packaging that’s reusable, recyclable, or home-compostable. It’s not unreasonable to ask companies what they are doing to reduce their environmental impact and what steps they take to protect livestock welfare and use their answers (and be alert for greenwashing in their answers) to inform your purchasing choices.

Extra Veggies

How much meat does your dog actually need? Can you add some more veg  (ideally locally grown to cut down food miles) to their diet? Personally, I don’t think you can feed dogs a 100% plant-based diet, but neither do most dogs require “prey-model raw” that is purely animal protein with no fruit or vegetables. Most dogs are able to consume somewhere between 5-30% veg (by food weight) without becoming nutrient deficient. You can reduce their meat/meat-rich wet/dry food and up their fresh veg intake. It’s been suggested that adding as little as 10% fresh food to a processed diet will reduce your dog’s risk of developing diseases such as some cancers, pancreatitis, and diabetes. You are improving your pet’s health and helping the planet. It’s such an easy small step.

Make Use of Food Waste

Look for fresh protein that would otherwise go to waste – short-dated meat/fish in the supermarket, offcuts from butchers and fishmongers, these protein sources are effectively carbon-free to you as you are saving them from landfill.

Novel Proteins

Longer term there are new lower environmental impact sources of animal protein. Insect protein is one front runner, but I’m not yet ready to risk basing my dog’s diet on it. The current production methods lend themselves to bacterial and mycotoxin infection as the insect larvae are bred at large scale on brewery or bakery wastes. Again, the nutritional profile is disparate to that from animal meats, plus there’s a unique problem with insect protein, even trace amounts of the chitin exoskeleton may cause auto-immune overstimulation because of chitin’s molecular similarity to pathogen cell-wall glycoproteins. But, insect protein is a vastly underutilised resource which seems likely to play a greater role in feeding a hungry world, and no doubt there will be more insect-based pet-foods in the coming years. It’s definitely one to watch.

Emerging from the realm of science fiction into science fact is bioreactor protein. The “lab grown” meat technology has so far recreated measly burgers and nuggets of animal flesh by cloning muscle cells taken from a living donor. This technology has yet to become commercially viable at scale. There are still issues with growing cells for infinite generations without the use of growth additives such as foetal calf serum (yes that’s as horrible as it sounds, Google it if you dare) derived from slaughtered animals. There’s a high energy cost in running cell incubators. But, using bioreactor artificial meat for pet feed is so much simpler than turning the soup of animal cells into something resembling muscle tissue that will be palatable to a human diner. For pet food it can just be fed as a protein-rich broth or dried into a protein powder to add to kibbles or canned foods. I do think we’ll see this technology come of age for pet food long before it’s mainstream for human foods.

In Conclusion

Back to today. For all the reasons I’ve stated here, I’m NOT letting my dog participate in Veganuary. As a scientist, and as an animal and nature lover, I choose NOT to feed vegan to my carnivore. Not until there’s a lab-synthesised food with an amino and fatty acid profile that matches fresh rabbit, with bioidentical versions of key vitamins and minerals and a water content of around 70% to match up with fresh food – and all for a carbon pawprint lower than using than locally sourced high welfare meat and vegetables.

Yes, I’d love there to be a way to feed her without using animal protein, but to keep her healthy that’s what she needs to consume. If you don’t feel you can feed meat to another animal, then please don’t get a carnivore as a pet.

TLDR – Why Not To Feed Dogs Vegan?

• Most vegan foods are dry kibbles – urinary tract strain as they evolved to consume 70% moisture foods
• Dry kibbles so high carbohydrate broken down through glycolysis, but dogs are better off using fats/proteins used in ketosis
• High legume content may be implicated in DCM heart disease
• Different amino acid profile than animal protein – may contain yeast extract
• Low in essential fatty acids
• High temperature cooked that makes it more difficult to digest
• Added synthetic forms of vitamins and minerals to make up the deficits, but these are inefficiency absorbed compared to the natural versions in fresh food.

TLDR – Best Foods?

• Feed fresh food from a range of protein sources with a variety of fresh veg and fruit
• Increase the veg to as much as your pet can tolerate (probably 5-30% of their meal)
• Source local and traceable food
• Watch the emerging alternative protein sources and maybe try these as snacks
• Look out for high ethical, environmental, animal welfare and food safety labelling
• Ask food companies what they are doing to reduce their environmental pawprint and improve livestock welfare.

Disclaimer: All views are my own, I am NOT a dog nutritionist but I am a PhD qualified biologist with a strong interest in feeding my dog to maximise her health and longevity. Sally is rawfed and eats a wide range of brands, she’s also food sponsored by Bella and Duke. I’ve been independently approached by two of the largest vegan kibble companies in the UK who offered me a “collaboration opportunity” for generous monetary remuneration. Both times I’ve refused as I feel my dog’s health is more important.