Veganism among humans is certainly on the rise. According to one 2017 report, 6% of US consumers claim to eat a plant-based diet – a 600% increase since 2014.
There are two main reasons people elect to feed their pets a vegan diet:
- Personal ethics (the human’s) - Pet owners turn to plant-based foods for ethical, environmental and health reasons, noting that byproducts from mistreated or diseased livestock are used in pet food and that animal agriculture is a leading source of greenhouse gases requiring copious amounts of water. Unlike cats, which are obligate carnivores (cats need nutrients found in meat to survive), dogs can draw the nutrients they need from animal or plant sources. However, if people are doing this because they are under the impression that it’s healthier, that’s just not true.
- Food allergies (the pet’s). Pets with food allergies are typically sensitive to specific animal proteins; eliminating processed animal products from their diet can help so long as the replacement diet is carefully formulated to provide essential nutrients. However, pets can also be allergic to grains such as corn, wheat, soy, barley, and oats.
While plant-based diets are known to have health benefits for humans such as reducing the risk of chronic illnesses like heart disease or Type 2 diabetes, pets will not necessarily get the same benefits. While dogs and cats get some of the same heart diseases that people do, they are very resistant to coronary artery disease, the main heart disease affecting humans. So, the nutritional strategies that are beneficial for preventing heart disease in humans are not useful in dogs and cats. Since obesity is the main risk factor for diabetes in cats and dogs, maintaining a pet’s ideal body weight with a consistent diet is the key to successful treatment of that disease.
Trying to feed a cat a vegan diet would be like me feeding my horses meat. This is forcing the animal it to eat something that it isn’t ideally designed to handle. People do this to make themselves happy; it’s not about the animal. A hamster or a goat would be a more appropriate pet for those wanting to feed a vegan diet.
For dogs, certainly vegetarian and vegan diets can be made, but they need to be done very carefully. There is a lot of room for error, and these diets probably are not as appropriate as diets that contain at least some animal protein. Compared to true carnivores, dogs produce more of the enzymes needed for starch digestion, have much lower protein and amino acid requirements, and can easily utilize vitamin A and D from plant sources, just as people do, which makes them more accurately classified as omnivores than carnivores. What all this means is that dogs are able to obtain essential nutrients from plants and animal proteins. Still, meat is generally regarded as a vital source of protein for dogs
Some nutritional deficiencies take months and even years to show up in vegan dogs and cats. Signs of malnutrition range from a dull coat and digestive issues to heart disease and early death. During the transition to a vegan diet, you should take your pet for more frequent vet checkups and blood work, including vitamin D testing.
Makers of plant-based dog foods, which include brands like V-dog, Wysong, Natural Balance, Halo, and Evolution, say their food meets the nutritional standards set by the Association of American Feed Control Officials, an organization of commercial feed producers and government officials that seeks to set dietary requirements for livestock, including dogs and cats. Vegan pet foods contain protein from plants such as soybeans, potatoes or peas and are supplemented with the vitamins, minerals and amino acids, such as vitamin B12 and calcium, that the feed organization recommends for dogs and cats. The diet needs to be nutritionally balanced. That means it has all the proteins, vitamins and minerals that they need in the correct ratios and with the best quality control. It isn’t easy to formulate a high-quality diet for dogs and cats, and it’s particularly difficult with a vegan diet.
Our knowledge of nutrition is not great enough to ensure nutritional adequacy, even if A.A.F.C.O. guidelines are met. To be safe, a new set of guidelines needs to be developed for vegan diets, along with long-term testing to ensure that the diets actually meet the animals’ requirements. This has never been done.
A study published in 2015 in the Journal of the American Veterinary Medical Association that looked at vegetarian commercial pet foods found that of the 24 foods tested, most were not compliant with the minimum labeling standards set by the feed producers’ group. Vegecat KibbleMix (a supplement designed to be added to a homemade diet) was prepared according to company instructions. Evolution canned diet for adult cats was marketed as a complete diet, requiring no additional preparation. The study showed both brands to be deficient in taurine, methionine, and arachidonic acid; with the Vegecat KibbleMix diet also deficient in the amino acids Lysine and Arginine. The Evolution diet was deficient in several B vitamins, as well as retinol, calcium, phosphorus, and overall protein. Hopefully, these deficiencies have been addressed since that article was published.
All three veterinary diets assessed met nutritional adequacy and labeling requirements, compared to only five of 21 over-the-counter diets that met both nutritional adequacy and labeling requirements. However, none of the three veterinary diets were completely free of animal-derived nutrients. Pet owners should consider combining brands in the hope that any deficiencies will at least differ between different diets, resulting in better overall nutrient composition.
The risks of feeding dogs or cats vegetarian or vegan diets include:
- Inadequate total protein intake (less than the 25 grams per 1,000 calories recommended). Dogs don’t utilize vegan protein as well as meat protein. A dog food which consists of 18% protein from meat may be adequate to meet your dog’s protein requirements, whereas a dog food which has 18% protein from corn may not be adequate. When choosing vegan dog food, choose options with higher protein percentages to compensate for the lower assimilation of vegetable proteins.
- Imbalance of amino acids, such as taurine and L-carnitine (dogs and cats) or arginine (cats only). Taurine deficiency leads to dilated cardiomyopathy, reproductive failures, and blindness. By the time a taurine deficiency is symptomatic in a cat, the damage is not always reversible and it will kill the cat if left untreated. Cats have a high requirement for arginine, which is necessary for converting ammonia into urea before it can be urinated out. Ammonia is a byproduct of breaking down protein for energy - without sufficient arginine the cat will develop ammonia toxicity from high levels in the bloodstream, which is fatal if untreated. Having enough arginine, which is found in the highest concentrations in meat, is vital, as cats get severely ill or may die after just one arginine-free meal.
- Deficiency of essential fatty acids arachidonic acid (cats only). This fatty acid is only found in animal fats. It is required for immune system function, blood clotting, skin and hair growth, and digestive and reproductive function. Without this ingredient, cats suffer from painful skin and digestive problems.
- Deficiency in vitamins and minerals (such as B vitamins, calcium, phosphorus, and iron) that are obtained ideally, or only, through meat or other animal products. Most animals are able to process beta-carotene from plant tissue in order to get enough Vitamin A in their diet - cats, however, lack this pathway and require a dietary source of pre-processed vitamin A such as animal fat or organ meat. Insufficient amounts may cause loss of hearing, blindness, and muscle weakness. Dogs and cats cannot efficiently make vitamin D in their skin from sunlight, so it needs to be in their diet as vitamin D3 (cholecalciferol), which comes from animal sources, not D2, which comes from plant-based sources. People and dogs can use D2 to some extent, but cats really need D3. Chronic vitamin D deficiency causes joint and muscle pain and may cause bone fractures. Cats have high requirements for vitamins B3 and B6, which are generally found in organ meat. B vitamins cannot be stored in the body and must be supplied daily. There is no vegan source of vitamin B12, which must be supplemented. Nutritional yeast is generally fortified with B12 and can be added to vegan pet diets.
Another unique problem for cats fed vegan diets is urinary tract disease. Some cats fed even the most nutritionally balanced vegan cat food end up developing crystals and blockages in their bladders that can be fatal. The breakdown of protein results in the acidic urine of carnivores. Plants digestion, on the other hand, results in production of urine with a higher pH. The high pH results in the formation of struvite crystals and stones in the urinary system which may result in partial or complete urinary obstruction (which may be life threatening), difficult urination, and blood in the urine. Bacterial urinary tract infections occur more commonly in urine with a higher pH. Accordingly, special attention to urinary pH is warranted for animals (and particularly, male cats which are more prone to obstruction due to their narrowed urethra) maintained on vegetarian diets. Regular monitoring of the urine acidity is essential.
Asparagus, peas, brown rice, oats, lentils, corn, Brussels sprouts and yeast will help acidify the urine. Buffered Vitamin C (ascorbic acid) is also a urinary acidifier. For more serious cases, the amino acids methionine and cysteine may be added to the diet.
If after all the warnings, you insist on feeding your pet a vegan diet:
- Be sure the food contains the right nutrients: Commercial vegan pet foods should contain Taurine, L-Carnitine, arginine (cats), B vitamins (especially B12), vitamin D3, and arachidonic acid (cats).
- Avoid vegan foods with corn as the main ingredient. Soybeans, rice, oats, yeast, lentils, quinoa, and soy protein isolate are more digestible forms of protein. Look for higher than normal amounts of protein in the diets.
- If making your own pet food, be sure to thoroughly cook all starchy ingredients for maximum absorption and decreased fermentation in the large bowel.
- Never feed vegetarian or vegan diets to puppies and kittens or to dogs and cats you plan to breed.
- If making your own pet food, consult with a veterinary nutritionist specially trained in balancing vegan diets. Do not trust recipes found online or on social media.
- It will be impossible to balance a vegan diet without the addition of many supplements. Do not skimp on these! Include taurine, L-carnitine, arginine (cats), arachidonic acid (cats), B complex, especially B12, iron, and zinc.
- Schedule veterinary wellness exams that include full blood work at least twice a year. Consultations with a cardiologist are recommended.
It is up to owners to make the best choices when feeding their pets. The dog or cat doesn't get a choice regarding the meal put in the bowl. Attempting to force ethics or beliefs onto an animal that will suffer from owner choices is unfair. No cat in the wild would choose a vegan diet; in fact, they would not survive.
I do not recommend vegan diets for any of my feline or canine patients.