Recently I have found myself ‘engaging’ in debates surrounding veganism. Some of these discussions have centred around pet nutrition, specifically the choice made by some pet owners to feed their cats a vegan diet. Whilst I can fully accept and appreciate another human beings choice to abstain from consuming meat, whether on ethical or health grounds, I cannot accept the practice of forcing a domesticated cat to become vegan. This blog post came about from these brief encounters with people who are feeding or want to feed their cats a meat free diet.
Cats as obligate carnivores- what does this even mean.
”An obligate carnivore (or true carnivore) is an animal that must eat meat in order to thrive ” (Syufy 2008).
If you studied biology at school you may remember that animals are grouped according to shared characteristics (taxonomy). Cats fall into the ‘Carnivora’ , an order of animals that also includes dogs, bears and seals. Some of the animals in this order are ‘omnivores’, meaning they are able to meet their dietary needs by eating plant matter. Others, like the domestic cat, are obligate carnivores, meaning they must eat meat to survive and, more importantly, to thrive.
From the shape of their teeth to the length of their intestines, feline bodies are not designed for consuming a plant based diet. Millennia of evolution along the line of eating a meat rich diet has meant that cat’s bodies have become ‘streamlined’, shedding ‘unnecessary components’ and creating essential ones along the way.
Teeth are an obvious clue as to what cats are designed to eat.
Blatantly obvious clue number 1: Cats have 4 canine teeth ( the long fang like teeth at the front of their mouths).These are specifically designed for catching, killing and holding prey. Not vegetables.
Blatantly obvious tooth based clue number 2: If you have a cat that doesn’t mind being watched , check out how they eat. Cats tend to use their ‘carnassial teeth’ to chew, pre molar teeth that are specifically designed for meat consumption . They act like scissors , making the meat easier for a cat to swallow. Unlike dogs, cats tend to have fewer molars, meaning they lack surfaces that would enable them to efficiently break down plant matter. The occlusal surfaces of their remaining teeth aren’t efficient for chowing down on vegetables.
Moving past teeth and on to other parts of the digestive process lends further evidence to why cats shouldn’t be forced into a life of veganism. From the very beginning of the digestive tract, cats have lost out on the ability to digest plant matter. Salivary amylase, a digestive enzyme used to start the process of starch digestion, is missing from cats mouths. Further down the digestive route (in the intestine) amylase is present, but at a mere 5% of the amount found in a dog. Other digestive enzymes found in a cats intestine point to their need for a meat based diet, as does their lack of the enzymes needed for starch digestion.
Cats, even those on ‘traditional’ diets, can be very fussy when it comes to food. This is one thing for healthy cats, but can be a real problem in cats that are poorly. It can become a vicious circle of a cat that is feeling sickly not eating which makes the cat feel worse so it doesn’t eat. In addition cats that are carrying too much weight can develop hepatic lipidosis, a potentially life threatening liver disorder, due to becoming inappetant. Cats may not find plant based diets very appetising and start refusing to eat. This can result in them developing further problems.
Comparing a cat to an omnivorous or herbivorous species will also show anatomical differences that preclude feline veganism. The length of a cats small intestine is considerably shorter, they only have a ‘vestigial’ caecum, and their colon is much shorter than herbivorous or omnivorous mammals. All of these again point to a meat based diet and an inadequacy in terms of digesting plant based starch and fibre.
So , dentition plus intestinal anatomy minus key digestive enzymes equals…well, doesn’t take a genius to see why they aren’t meant to live on veggies alone.
If that wasn’t evidence enough, lets take a look at some of the health problems that cats presented with meat free meals could develop. These problems can arise due to vitamin and protein deficiencies. The domestic cat’s evolutionary journey has thrown up a few quirks in terms of vitamin and amino acid requirements .
Vitamin A is necessary for maintain healthy vision, bone and muscles. Most herbivorous or omnivorous mammals can meet their need for it by converting beta carotene, a plant pigment, during the digestive process. Cats can’t. They lack the enzyme needed for this, meaning they really on ‘ready made’ , ‘pre packaged’ vitamin a. This is easily obtained through eating animal products.
Methionine is another essential amino acid for cats, and deficiency is also possible when they are fed a vegetable based diet. Skin problems, especially around the nose are seen in cats that are lacking this protein.
Taurine is another amino acid (protein) that is essential for a cats sight, nerve function, immune system and heart. Carnivorous diets supply plenty of taurine, whilst cereal or vegetable diets have inadequate or minimal amounts. Deficiency of taurine can result in a cat developing life threatening and (potentially) deadly conditions such as Dilated Cardiomyopathy (DCM) and Feline Central Retinal Degeneration. In pregnant cats it can also cause the unborn kittens to be damaged.
During my recent conversations I have been told ‘ well, my cat is doing great on a vegan diet so far’, having only been on it for a few days, weeks or months. And the owners are probably right. The cats probably are coping. For now. Switching to a plant based diet isn’t likely to cause these diseases to develop immediately. In fact, signs that something bad is happening to your cats health will only appear after a long period of your pet being taurine deficient (anywhere from 5 months to 2 years).
Synthetic forms of both vitamin A and Taurine are available, but relying on these to feed an obligate carnivore raises a separate set of ethical questions. In addition, the nutritional adequacy of ready made vegan feline diets has been questioned, with studies finding them to be lacking in essential elements.
Another health risk for cats, especially male cats, fed on a vegan diet is FLUTD (feline lower urinary tract disease). These cats can develop abnormally alkaline urine due to the plant based proteins in their diet. Meat based diets result in acidic urine, which is normal for cats. Alkaline wee provides the right environment for bladder crystals or stones to form in . These can cause irritation to the lining of the bladder , leading to inflammation (cystitis) and infections, pain and, more seiously , blockage of the urinary tract. Urinary blockage means a cat cannot pass urine, and without veterinary attention a cat will die .
Time to get off the soap box….
At the end of the day, I would advocate that any responsible cat owner…or human that cares for a cat…or cat ‘guardian’ … should seek to do the best for the cat. Informed choices regarding their care should be made, including what they are fed . This should be done with the individual animals best interests at heart. If a pet owner still decides that this means feeding a vegan diet to their cat , the cat should have regular check ups scheduled with their vet, to ensure that the cat never suffers due to food source.