A growing number of people switch every year to vegetarian or vegan diets, and so the number of pet owners who search for the same diets for their pets. Their choices are based on ethical, environmental or health reasons. But, are vegan diets right for pets? Or do the owners cause harm by switching them to these types of food?
Vegan food for pets
Let me open by saying that I'm a vegetarian, from compassion reasons. I don’t feed my dogs a vegetarian diet for two reasons. First, I believe that given the choice, they would choose a steak or chicken leg and not garbanzo beans. Second, I know that biologically they are built to digest animal-based proteins better than plant-based ingredients.
I receive a lot of questions from loving pet owners who have decided to switch their pets to a vegetarian diet. My goal in this article is to provide you with the information, whether or not this diet does fit your pet and how to make sure to make this change in the best way possible.
In many cases, the main reason for switching a pet to a plant-based diet is because of the owner's ethical reasons. I hear many sentences like: "I want to feed my pet without exploiting other animals", etc.
But, there are some cases when the pet had developed a sensitivity to animal-based protein and so it requires to digest only plant-based. In these cases, the only way to ease the digestive tract is to eat a vegetarian diet.
Plant-based food for dogs and cats
Around 33 thousand years ago, dogs have been domesticated and became dependent on humans as their food suppliers. As a result, the have become genetically adapted and developed the remarkable ability to digest carbohydrates. Hence, from a biological perspective, dogs are considered to be omnivores. Their digestive tract is built to digest and absorb animal-based ingredients as do plant-based. Meaning, they can eat and function just fine on a vegetarian or vegan diet.
Contrary to that, cats have been domesticated around 10 thousand years ago and yet almost without any biological change. Cats have been and stayed obligate predators. As such, their digestive tract is built to work almost exclusively on animal-based proteins. To keep it simple, cats are not built to eat vegetarian diets, especially grains.
In general, I can say that modern cats and dogs eating commercial dry food from bags or cans, are really not their ancestors and so eating biologically appropriate food may seem less important.
In the past, natural selection preferred animals with certain characteristics (preference to high caloric food, willingness to hunt, uncontrolled eating), which doesn't suit modern domesticated living and the long-life span of our pets.
In order for modern pets to survive in the modern environment, for their long lives, they need to eat food that has high palatability, high digestibility and to be complete and balanced. A proper diet prevents nutritional deficiencies and keeps the pet healthy. So, the diet should contain all the necessary nutrients according to each pet's needs. The emphasis is on nutrients and not specific ingredients.
Theoretically, if we agree on that, there seems to be no reason why a diet based exclusively on vegetarian ingredients and added supplements, won't meet the necessary nutritional requirements of dogs and cats.
A study conducted in 2015 checked to see if 24 vegetarian dry and canned pet foods meet the AAFCO standard as complete and balanced food. The study found that 6 pet foods didn’t meet the minimum requirements. Previous studies also found contradictions between the labels and the actual levels of nutrients.
Of course, that these studies don’t reflect on all foods or home feeding, but they show, that as in meat-based foods, there are things to notice also in vegetarian foods and you shouldn’t rely only on one type of food and you better vary between several brands or flavors in order to prevent deficiencies.
Is there a danger in veganism for dogs and cats?
First of all, since we are talking about a diet built exclusively on carbohydrates, I will focus my discussion mainly on sugar. The digestive system of dogs and cats converts carbohydrates to sugars (glucose). While glucose is a vital energy source for bodily cells, excessive amounts of it, those unnecessary for daily activity, will revert to fat stored in fat cells. All those excessive sugars may lead to obesity and diabetes.
In addition, in order to transport glucose from the blood to the cells, the pancreas needs to produce the enzyme Amylase. As glucose levels rise in the blood, thus grows the need to produce more of this enzyme. In a state where the majority of the diet is based on carbohydrates and sugars, there may be a burden on the pancreas; a thing that may damper its efficiency.
As opposed to dogs, cats have a permanently active process of creating glucose from amino acids (the building blocks of proteins) and glycerol (the backbone of fats). This is why they need high levels of protein and fats and don’t require any carbohydrates in their diet. It is the presence of carbohydrates that will damage and put off balance their natural metabolic processes.
Second, carbohydrates contain nutritional fibers. These are plant-based compounds which don’t digest though contribute to the health of the digestive system. A small amount of fibers (around 5%) is recommended for dogs (even less of that for cats). But, large amounts may have undesirable consequences. For example, the presence of a large number of fibers may lower the absorption of vital minerals (such as Calcium, Magnesium, Zinc, Iron, and Iodine).
A third point I would like to refer to is that plant-based ingredients cause the urine to be more alkaline than acidic. This disturbs the PH balance and may lead to inflammation and crystals. This is why it is important to do routine urine acidity tests.
And finally, I think another concern about feeding a plant-based diet is a lack of vital amino acids which may lead to damage to muscles, especially of the heart. In cats, there is also the fear of a shortage of Taurine, vitamin A, and vitamin B12. Without a constant supply of these nutrients, cats may develop heart and liver problems.
Vegan food isn’t for every pet
As with every type of food or ingredient, each pet is different, and with all due respect to our desires as pet owners, not everything suits everybody. Just like a certain type of meat-based food won't fit a certain dog, as do with the vegan/vegetarian food. Meaning, you may wish to feed your pet a vegetarian diet, but it won't suit their digestive system.
So, how would you know if the food fits them or not? As with any other type of food, you need to look at your pet, touch it, and follow up regularly after her condition.
Here are several points that I recommend paying attention to:
1. Healthy stool – it needs to be firm, small volume, without any unusual colors or textures, and not many times each day. Because we are talking about plant-based food which has lower digestibility than meat-based food and contains more fibers, things may look different. Meaning – the volume will be quite large and several times daily. This will still be ok. Just don’t let it have textures or colors. Of course, not diarrhea or loose stool. These may indicate that the food just doesn’t fit your pet.
2. No gas – your pet starting to pass wind or burp a lot may indicate that there is too much gas activity in the digestive system. Due to the fiber content.
3. Healthy skin and coat – any shedding or dry reddish flaky skin can indicate a shortage of essential fatty acids (omega 3) or a high amount of omega 6 fatty acids. This is a common thing in foods which doesn’t contain fats from animal sources.
4. Proper weight – you need to monitor your pet's weight and see that it doesn’t gain or lose pounds. On the one side, these foods contain a high amount of sugars which may lead to obesity; and on the other, they contain low levels of energy (due to low fat levels) which may mean that your pet won't receive the calories it actually needs.
5. Inflammations – mainly in the ears or the urinary tract. Alkaline urine leads to bacteria formation which also feeds on the high sugar levels in the diet. Yeast which lead to ear infections also feeds on these sugars.
6. Anything out of the ordinary – such as lack of energy, searching to graze on grass or things to chew on, difficulty walking or any sign of joint pain (meat protein and bones contain cartilage and glucosamine which protect the joints and are missing from veggie diets and also veggie diets are usually high in omega 6 which is pro-inflammatory), excessive thirst, etc.
If you notice one or more of these signs, I recommend visiting your vet and of course changing the food.
How to feed a vegetarian diet in the right way?
First, because dogs and cats don’t produce Amylase (the enzyme responsible to break carbohydrates) in their saliva and they don’t chew the food (as we do), you must cook and grind the food in order for it to arrive ready to be digested by the stomach.
Second, as I mentioned before, I don’t recommend feeding just one type of food but to feed different things or different brand if feeding dry commercial food.
I don’t recommend feeding a complete vegan diet but to try to incorporate ingredients that will be easy for you; such as fish oil (dogs and cats cannot produce the necessary amounts of fatty acids from plant-based ingredients as they do from animal sources), sardines, hard-boiled eggs and more.
And finally, I recommend adding nutritional supplements that will assist the digestive system (such as digestive enzymes) and superfoods that will provide extra whole food nutrients.
I understand the desire to follow our ethical code when we make decisions about ourselves. But, in my opinion, we need to put our pet's health and wellbeing first, above our egoistic desires. If we enter our family a partner that is considered a predator, we mustn't turn it into an herbivore for the reason of our convenience. Like anything in life, we must accept certain compromises. Or at least understand the meanings of our decisions.
Sivan is a clinical pet nutritionist and a HACCP food safety team manager. She has been working in the pet nutrition field since 2010; while formulating and managing herbal remedies as well as dehydrated dog food. Along with being a pet parent herself, she consults to pet-owners and pet food manufacturers with the formulation of pet food and treats and lecturing on natural pet nutrition. She is closely allied with Paw Kitchen as an on-board nutritionist.