Written by; Heather Clemenceau
Humans have teeth ideally suited for grinding. Plant-based eaters often tell meat-eaters that “if we were meant to eat meat, we would have canine teeth.” Well of course that’s true, but look at the cat’s dentition. We sometimes claim that humans are plant-eaters based on our dentition, while hypocritically asserting that, despite having canines, we shouldn’t have to feed cats meat if it interferes with our belief system.
Since I wrote my first and only blog post on vegan cats and dogs, not much has changed. Cats are still strict carnivores that rely on nutrients in animal tissues to meet their specific nutritional requirements. To the best of my knowledge there are no long-term clinical studies of cats (or dogs) eating vegetarian or vegan diets, with or without non-vegan control groups.
Despite rather scant literature on the subject matter, the limitations of substituting animal-origin protein with plant-origin protein in food formulated for cats is being increasingly recognised. Simply looking at the overall protein content of a food is not enough to determine whether the food is a good choice for cats. We must consider then when feeding – what is the biological value of that protein to the cat? The natural diet of cats in the wild is a meat-based diet of rodents and birds. Cats are metabolically adapted to preferentially use protein and fat as an energy source, not carbohydrates. Not all proteins are equal either – proteins are made up of amino acid chains and there are a myriad of different combinations that serve many functions in the body. Since meat is a natural food source for cats, it is easy to conclude that meat proteins will have a higher digestibility for cats than plant proteins.
I do understand the motivation by some plant eaters to reduce their cat’s ecological pawprint in any way possible. But as
“Cats have a limited ability to adjust protein utilization to the amount of protein in their diets. In other words, they need to burn protein for energy even if they aren’t getting enough in their diet. Cats have lost a number of metabolic pathways that omnivores still utilise to metabolize plant-based foods. They have lost these pathways because in their natural habitat they hunt prey species that are high in meat-based protein, so they no longer needed the ability to efficiently metabolize plant material.”
Lyn Thomson, BVSc DipHom
mentioned in my previous blog post on the subject, the vast majority of cat and dog food is derived from the meat industry, so additional animals are not killed to feed dogs, cats, or ferrets. Nevertheless, the feeding of vegan diets to cats, dogs, or ferrets does problematize the definition of “vegan” for many people. They quite understandably feel that if they buy any meat-based pet foods, they are supporting the meat industry and not carrying out the “noble vegan boycott” of those industries. Over time I’ve found that some vegans/vegetarians invariably equate non-animal food sources as some sort of penultimate launching pad towards spiritual purity. But when we insist that cats, who are obligate carnivores, actively participate in that effort, we’re anthropomorphizing them. We don’t ask that cats share our religion, so why must they share our diets?
Moreover, sometimes we steadfastly refuse to consider the implications of the few studies that are available that cast doubt on the long-term health effects of vegan diets, relying instead on anecdotal evidence. But consensus via anecdote is not empirical evidence. Anytime the main “evidence” for a product’s efficacy is testimonials or other anecdotes, everybody’s woo detector should light up. And even though you may have consistently observed a phenomenon again and again (cats eating a vegan diet and thriving), there is no guarantee that your next observation will agree with the previous one. For example, even if you’ve only ever seen white swans, it is still incorrect to assume that all swans are white. So, if you require that all knowledge must be based on your personal observation alone, you can never be sure you know anything.
If the studies mentioned in the previous blog post weren’t sufficiently convincing that vegan foods for cats are, at the very least, completely experimental, perhaps the following study and interview will make a skeptic of some readers. As it turns out, there is more literature available on vegan cats, but we were just looking for it in English! Both the study and interview have been translated from their original German, and should you wish to read them or translate them yourself, the original links are included.
The Interview – Dr. Kienzle and Spiegel Online
The following translation is ©Anke Hagen. Translated from the German original and supplemented with additional information on Prof. Kienzle by Anke Hagen. Should you share this, kindly make no alterations whatsoever – thank you.
Prof. Dr. Ellen Kienzle is the head of the Department of Animal Nutrition and Dietetics at the Ludwig-Maximilian University of Munich in Oberschleißheim.
She in on the Livestock Commission and has obtained credentials at the ECVCN committee. In addition to student counselling her research field includes the veterinary nutrition of dogs, cats and horses
The European College of Veterinary and Comparative Nutrition (ECVCN) is recognized throughout the veterinary profession for its progressive leadership, for the high standard of professional excellence of its members, the Diplomates.
In order to become a Diplomate, veterinary surgeons, known as Residents, must undergo a rigorous training programme in either Large or Small animal nutrition, supervised by recognized veterinary specialists e.g. other Diplomates or Professors of Nutrition at a number of Universities
What does ‘ECVCN Diplomate mean? A specialist?
A ECVCN Diplomate is someone who has founded the ECVCN, or has successfully passed the examination of the European College of Veterinary and Comparative Nutrition, a EBVS-recognised College.
The objective of the European College of Veterinary and Comparative Nutrition (ECVCN) is to advance the quality of animal health care in Europe by increasing the competency of those who are active in the field of veterinary nutrition.
The ECVCN was founded in 1998 from the European Society of Veterinary and Comparative Nutrition.
The college obtained full recognition by the European Board of Veterinary Specialisation (EBVS) and currently counts 39 Diplomates.
Prof. Kienzle does not recommend a vegan diet for dogs! She said an ‘ovo-lacto vegetarian diet’ (as opposed to a vegan diet) is POSSIBLE (but not optimal) for dogs, but then only under the strict supervision of an expert veterinary dietician. It is very rare to find persons with a qualification like hers. She says that whether or not one adds raw meat or not or feeds dogs an ovo-lacto vegetarian diet, people generally tend to underestimate the canine calcium requirement, because their ability to metabolize calcium (their uptake efficiency) is far worse than ours.
When asked by Spiegel Online how a calcium deficiency manifests in dogs, Prof. Dr. Kienzle replied:
“Kienzle : dogs develop skeletal diseases such as brittle bones, which can manifest themselves within two years. With puppies this can happen within a few weeks. Unfortunately, you can not tell that a dog has a calcium deficiency on the basis of a haemogram in time! One only notices the lack when it is already too late clinically speaking. Pregnant bitches (female dogs) have a particulary high calcium requirement A particularly high calcium needs are pregnant bitches and especially puppies who pick up weight particularly fast. In such cases, I strongly advise heeding *specialist* veterinary nutritional advice.
SPIEGEL ONLINE: Is not it enough then to simply feed them more eggs and dairy products?
Kienzle: No, that’s not enough. You have to supplement with calcium. Calcium tablets used in human medicine are not suitable for this incidentally, the doses are far too low.
SPIEGEL ONLINE: Can’t dog owners simply rely on ready-made vegetarian feed mixtures to ensure that the dog has no deficiencies?
Kienzle: I would not rely on that. The vegetarian dog mixtures that exist on the market, usually come from vendors who lack the necessary expertise. Incidentally, the Stiftung Warentest recently tested ‘vegan’ cat food and found chicken components in a vegan food mixture intended for cats and dogs.
SPIEGEL ONLINE: So it is possible to feed dogs vegetarian food. What about vegan nutrition?
Kienzle: At a stretch, and if you are absolutely desperate to do that, you can do that with an adult dog, but only in keeping with the aforementioned reservations and recommendations. But in pregnant or lactating bitches and in puppies a vegan diet is not acceptable.
SPIEGEL ONLINE: Do dogs accept the transition to a vegetarian diet that simply?
Kienzle: Dogs might not accept the new food at first. But usually you can get them to accept it by letting them starve for a while. I would not recommend that. Whether a vegan regards that as being ethical or not is something he will have to to reconcile with his own conscience.
SPIEGEL ONLINE: I’ve heard that it is essential to supplement two substances on a vegan diet: L-carnitine and taurine. Is that correct?
Kienzle: That statement cannot be validated in such a generalized sense – it depends on the one hand on the breed of the dog, on the other hand, on the individual nutritional requirements. But on a vegan diet, it would not be harmful to supplement with both substances, because a shortage of either of them would mean that the animal is in danger of suffering from heart muscle disease.
SPIEGEL ONLINE: People who feed their dogs vegan food, always claim that their dogs benefit health-wise. Can you confirm that?
Kienzle: I regard a generalization like that as being highly problematic and questionable. Those who feed their dogs raw meat also claim the same things. We know that both dogs and horses display very strong placebo effects, simply because the animal gets more attention from its guardian/keeper. But of course, you will always find individual cases where a dog with an allergy or skin disease, for example, will benefit from a change of diet.
SPIEGEL ONLINE: Can you feed a vegan diet to cats?
Kienzle: Dogs have been domesticated for about 20,000 years and have adapted their diet and their metabolism to humans. Dogs are much more flexible in their diet than cats who have indeed continued to feed on mice during their domestication – which is precisely why they were kept by humans in the first place. Feline metabolism has also not been researched in as much detail as that of the dog. I therefore reject the nutrition of vegan food to cats, and an ovo-lacto-vegetarian diet for cats is also to be regarded in a far more critical light than one for dogs. In addition it is also difficult to change a cat’s nutrition because they are subject to stringent nutritional conditioning. It would not function to allow a cat to starve. The cat would die.
SPIEGEL ONLINE: What is your view of carnivorous companion animals in general?
Kienzle: I find it questionable that vegans even keep predators as companion animals at all. The animal serves the purpose of entertaining them, which alone is selfish enough. Then in that case, the least you should do is to respect the needs of the animals. You don’t necessarily have to keep a carnivorous companion animal. One could also keep a rabbit or a small guinea pig. They are very amusing and loving companions too.”
Interview conducted by Jens Lubbadeh.
“Not all proteins are equal. Proteins are made up of amino acid chains and there are a myriad of different combinations that serve many functions in the body. Proteins are structural and tissue components in the body, enzymes and antibodies and serve messenger and transport functions. Ingested proteins will vary considerably in how well they are utilised by the body. Plant-based proteins do not have the same amino acid profile as meat-based proteins and these differences are crucial to cats.”
Lyn Thomson, BVSc DipHom
The Study – Dr. Radka Engelhard, DVM – Field Study of Vegetarian Food for Dogs and Cats
The following translation is joint collaboration between Tamara Goertz, Dr. Werner Liesack and Birgit Liesack. ©Tamara Goertz et al. Translated from the German original published on http://www.vetmed.uni-muenchen.de
“In this study interviews were conducted with 54 owners of dogs and five owners of cats, for a total of 86 dogs and eight cats. These owners were feeding their dogs and cats a vegetarian diet and for this reason they were picked for the interviews.
The questions in the interviews included, what type of vegetarian dishes were fed and what feeding techniques were used, and what portions were dispensed. These questions were asked on a standard questionnaire.
The results of these questions were:
66 adult dogs received 11 per cent ovo-lacto vegetarian diet (which includes eggs and dairy), 47 per cent lacto-vegetarian diet (dairy), 29 per cent vegan, 13 per cent semi-vegetarian (with not pure vegetarian supplementary food), for eight vegan pups and eight vegan cats.
As well, the results of all details of illnesses were recorded and clinical checkups were undertaken, and in some cases blood work and urine samples were taken.
And finally, commercial pure vegetarian animal food was tested for its suitability.
- The main reason for the participants’ involvement (in the study) was to present the ethical-religious aspects, that man has no right to kill animals for their meat. As well, that the current meat standards entail many health risks.
- The supply of protein was insufficient by more than half of the adult dogs. Also, results often showed that the intake of S-containing amino acids, such as cysteine, were too low. Nonetheless, all plasma parameters were tested for protein intake (total protein, albumen, urea) inside the reference area.
- The typical mistake made in the homemade ratios of mineral elements were also found in vegetarian dogs. Sixty-two per cent of the dogs were lacking the minimum calcium requirement, and about half the dogs were lacking the minimum phosphorus requirement. An unbalanced Ca/P ratio was glaringly apparent. Also, 73 per cent of the dogs lacked sodium.
- In the trace elements the supply of iron, copper, zinc and iodine were often insufficient. The content of iron, copper and zinc in plasma was mostly below the reference value, but there was no clear relation between their intake and plasma content.
- It was discovered that vitamin D in the vegan rations were often insufficient. Also here were reduced plasma content of 25-OH-vitamin D; however, no firm relationship to vitamin D intake was recognized. A total of 56 per cent of dogs received insufficient supply with vitamin B12. Supply with panthotenic acid was frequently marginal.
- The adult dogs displayed no clinical deficiency from the insufficient vitamin intake.
- The vegan puppies at eight weeks of age were only about half of the expected body weight.”
Biological value (BV) is a number from 100 down to 0, that describes how well a protein is absorbed by the organism’s body. More precisely, it is the measure of the percentage of the protein that is actually incorporated into the proteins of the body.
When one or more of the essential amino acids are missing or present in low numbers, the protein has a low biological value.
Unfortunately, the vegan lifestyle can never be unassailably consistent, or free of contradiction. In fact, one could say that most vegans already support the meat industry if they eat in any restaurants that serve meat, so just like my non-vegan cats, we’re both supporting agribusiness. And depending on where you live and what vegan cat food you buy, it may not even be vegan anyway, since Dr. Kienzle’s research has shown that chicken has been determined to be an ingredient in some foods. Perhaps this explains the relative good health of some vegan cats in studies – they’re actually getting biologically valuable proteins from ingredients that weren’t intended to be added to the food!
Even by purchasing only vegetarian or vegan special product lines exclusively, we might still be unknowingly supporting the meat industry. This is because so many of the cruelty-free foodstuffs and other products we love to eat are owned by big food conglomerates (Conagra used to own Lightlife, the maker of “Smart Bacon;” Dean Foods purchased Whitewave, makers of “Silk;” Kellogg owns Morning star Farms who make meatless sausages and burgers, and Kraft owns vegetarian burger company Boca). As if none of that were bad enough, Big Tobacco company Philip Morris owns Kraft. As unhealthy as Velveeta is, probably Marlboros are worse….
But even without all this skepticism of vegan diets by veterinarians and veterinary nutritionists, is the presence of canine teeth not suitably convincing? Some people already remove a cat’s claws, and aside from this being extremely painful to the cat, it also greatly infringes upon a cat’s ability to partake of its natural behaviours. Must we inflict extruded vegetable pellets or vegetable mush on them as well?
It is both ethical and humane to permit cats to scratch and eat meat. These are both undeniably inherent feline attributes. If we can’t accept a cat’s natural ways of being then perhaps a different companion animal would be in order?
I do love this tweet, and appreciate Ricky Gervais advocating for the true nature of cats everywhere.