Vegan canine diets
3 The health of vegan dogs
2 Requirements of vegan diets
2.1 Ensuring palatability
2.2 Nutritional content
3.1 Population studies
3.2 Reported cases
4 Urinary alkalinisation
The death and suffering inflicted upon approximately 80 billion chickens, pigs, sheep, cows, and other animals, both intensively and extensively farmed, who are slaughtered annually, and upon similar numbers of intensively farmed or wild-caught fish, in order to fulfil the desire of some human beings for meat, has been thoroughly documented; as have the deleterious environmental impacts of both intensive and extensive animal farming.
It is because of the ethical concerns of a growing population of vegetarian animal guardians, and because of medical conditions such as allergies which are caused by beef, lamb and other meat-based dietary ingredients, that vegetarian pet food brands were first developed. However, canine vegetarian diets remain the subject of some controversy, which is exacerbated by ignorance of the health and nutritional issues involved, including among veterinarians and other experienced animal carers.
To assist animal guardians, animal carers and veterinary personnel who wish to gain a sounder understanding of these issues, this page examines the palatability, nutritional and bioavailability requirements of vegetarian canine diets. It provides the results of two population studies of the health of vegetarian dogs, and describes the health benefits reported in some dogs after transititioning to nutritionally sound vegetarian diets.
2 Requirements of vegan diets
Whatever combination of animal, plant, mineral or synthetically-based ingredients are used, diets should be formulated to meet the palatability, nutritional and bioavailability requirements of the species for which they are intended.
2.1 Ensuring palatability
The fixation of some dogs to meat-based commercial brands to which they have become accustomed is primarily due to the addition of ‘digest,’ the industry euphemism for partially digested entrails, usually of chickens. According to Small Animal Clinical Nutrition, “Digest is probably the most important factor discovered in recent years for enhancing the palatability of dry food for cats and, to a lesser degree, dogs.” (Lewis et al. 1987).
Although usually less of a problem than in cats, patience and persistence may still be required when altering the diets of some dogs who have been exposed to digest long-term. In difficult cases it may first be necessary to withhold all food (not water!), for one day. This will stimulate the appetite without harming healthy adults. It is always advisable to change the diet gradually, e.g. by using 90% old and 10% new diet for a few days, then switching to 80% and 20% for a few more days, thereby transitioning to the new diet over several weeks, or even longer if necessary. A gradual change is more acceptable behaviourally in difficult cases, and also allows an appropriate transition of digestive enzymes (to the extent possible) and intestinal flora (bacteria), thereby minimising the chance of gastrointestinal reactions such as diarrhoea.
Dog guardians should demonstrate by their behaviour that they consider the new diet just as edible as the old (without possibly warning or alarming their dog by making a fuss). They should not be concerned if their dog eats around the vegetarian food at first; just having it in close proximity to the other food will help the dog make the necessary mental association. Mixing the food thoroughly may help, as may the addition of odiforous (the sense of smell is very important) and tasty additives, such as nutritional yeast, vegetable oil, nori flakes and spirulina. Gently warming the food may also help. Guardians should remove uneaten food and offer only fresh food.
The most important factors for difficult dogs are gradual change and persistence. Using these principles, the most stubborn of dogs have been successfully weaned onto healthy vegetarian diets. Vegetarian dog food recipes may be obtained from Peden (1999) and Gillen (2003) and from some suppliers of nutritional supplements.
2.2 Nutritional content
Dogs may be biologically classified as omnivores, due to their ability to subsist on a mixed diet of animal and plant-based material in their natural environments. They are less adapted to a carnivorous diet than cats, and their nutritional needs are easier to meet on a vegetarian diet.
Nevertheless, to safeguard health and avoid cardiac or other diseases, vegetarian diets must be complete and reasonably balanced with respect to all essential nutrients. This may be achieved by adding a vegetarian nutritional supplement to a home-made diet (recipes are available from some suppliers of supplements), or by using a nutritionally complete commercial diet. Ideally this should be certified as meeting the nutritional standards of the Association of American Feed Control Officials (AAFCO), or equivalent national authority.
The Committee on Animal Nutrition, reporting to the Board of Agriculture within the US National Research Council (NRC), has developed nutritional standards for at least 15 species. Historically AAFCO used the NRC recommendations, but in 1993 began publishing its own expanded nutrient requirements, which are now widely recognised as the required nutritional standards for animal feeds.
In order to meet AAFCO nutritional requirements, manufacturers of vegetarian (and, in some cases, processed meat-based diets), diets rely upon vegetable, mineral and synthetic sources of nutrients otherwise derived from animal tissues.
The bioavailability of nutrients (extent to which they are available to the tissues) is determined largely by their level of digestibility into simple molecules capable of absorption through the intestinal mucosa. The importance of digestibility is increased in animals such as cats and dogs that have relatively short intestinal tracts. Fortunately, several studies have demonstrated ample digestibility of vegetarian dietary ingredients in cats and dogs.
The digestibility of some protein sources has been evaluated in the dog. Hegsted et al. (1947) found that the apparent digestibility of proteins in an all vegetable diet containing white bread, corn, rice, potatoes, lettuce, carrots, onions, tomatoes and applesauce was 80.0 (plus or minus 7.7%). James and McCay (1950) reported that the apparent protein digestibility of commercial, dry-type food, containing both vegetable and animal proteins, ranged from 67 to 82% for adult dogs. Kendall and Holme (1982) reported the apparent crude protein (Nx6.25) digestibility coefficients for textured soy protein, extracted soy meal, full-fat soy flour, and micronised whole soybeans ranged from 71 to 87%. Moore et al. (1980) reported apparent digestibility values of soybean meal, corn, rice, and oats by mature Pointers to be in the range of 77 to 88%. Their data revealed that normal cooking procedures did not significantly influence the digestibility of rice, oat, or corn protein. Their data also indicated that increasing the fat content of the diet from 10 to 20% did not alter the digestibility of nitrogen in a corn-soybean-based diet. Burns et al. (1982) showed that the apparent digestibilities of lactalbumin, casein, soy protein, and wheat gluten are 87, 85, 78, and 77%, respectively (National Research Council 1986, 12). Clapper et al. (2001) compared the canine digestibility of five soybean protein sources to that of poultry meal, and found the soy protein to offer a viable protein source. They stated, “Soy protein, when combined with other protein sources that contain complementary amino acids, can provide an economical source of highly available and consistent-quality protein to the canine.”
Pet food manufacturers are well aware of the acceptable digestibility of plant-based ingredients, which make up a large proportion of the products they sell.
3 The health of vegan dogs
3.1 Population studies
Systematic reviews: 1
Analysis of 16 studies on the impact of vegan diets on cat and dog health
Domínguez-Oliva et al. (2023) concluded, “there was no overwhelming evidence of adverse effects arising from use of these diets and there was some evidence of benefits. … Much of these data were acquired from guardians via survey-type studies, but these can be subject to selection biases, as well as subjectivity around the outcomes. However, these beneficial findings were relatively consistent across several studies and should, therefore, not be disregarded.” They advised, “… if guardians wish to feed their companion animals vegan diets, a cautious approach should be taken using commercially produced diets which have been formulated considering the nutritional needs of the target species.” [i.e., that are nutritionally-sound].
Studies supporting vegan or vegetarian dog food: 9
Prospective clinical study of 15 dogs
Linde et al. (2023) studied 15 dogs fed vegan diets (V-Dog ‘Kind Kibble’) for one year after previously being fed meat-based diets. They evaluated clinical, haematological (blood cells etc.), and nutritional parameters at 0, 6, and 12 months, including complete blood count (CBC), blood chemistry, cardiac biomarkers, plasma amino acids, and serum vitamin concentrations. All dogs maintained their health status. Three who had been overweight or obese lost weight. Blood results confirmed the diet provided all essential amino acids, and for several nutrients blood levels increased. In some cases previous deficiencies reversed, without supplement use.
Survey of 1,189 North American dog guardians
Dodd et al. (2022) collected dietary information from 1,189 dog guardians, including 357 feeding solely vegan diets, who fed these diets for 3 years on average. Vegan dogs were reportedly more likely to enjoy very good health, and less likely to suffer ocular, gastrointestinal and hepatic (liver) disorders. No health disorders were more likely, and longevity of previously-owned dogs was reportedly 1.5 years greater, when fed purely vegan diets.
Survey of 100 UK dog guardians
Davies (2022) surveyed 100 dog guardians who had switched to a nutritionally complete vegan dog food designed by UK veterinarians. “The vegan food was acceptable (palatable), and appetite and body weight were not adversely affected. Changes, including improvements, were reported and statistically significant at p< .05 in the following areas: activity, faecal consistency, frequency of defaecation, flatus frequency, flatus antisocial smell, coat glossiness, scales in haircoat (dandruff), redness of the skin (erythema, inflammation), itchiness (scratching; pruritus), and anxiety.”
Survey of 2,536 mostly European dog guardians
Knight et al. (2022) studied 2,536 dogs fed vegan or meat-based diets for at least one year. Being a very large-scale study, these results confer a high degree of statistical reliability. Included were guardian opinions of health – which are not always reliable – as well as a range of more objective data, such as prevalence of medication usage. Many different indicators of health were pooled. The researchers concluded that the healthiest and least hazardous diets for dogs are nutritionally sound vegan diets.
Clinical study of 38 dogs at Ross University School of Veterinary Medicine, St Kitts
Cavanaugh et al. (2021) conducted physical examinations, blood and urine tests, and cardiac ultrasounds, on 34 previously meat-based dogs fed vegan dog food (V-dog) for 3 months, and four control dogs. Dogs transitioned onto the vegan diets did not develop any essential amino acid deficiencies or taurine deficiency. Rather, they had taurine concentrations higher than their previous values, and higher than the whole blood taurine concentrations of the control dogs fed meat-based pet food. Results of clinicopathologic (haematology – blood cell type analysis, biochemistry – blood enzyme analysis, and urinalysis) and echocardiographic testing (cardiac ultrasound) indicated the health of the dogs was maintained and did not deteriorate after 12 weeks on the vegan diet.
Veterinary masters theses
Semp (2014; n = 174 for history, n = 20 for clinical examinations and haematology) and Keimer (2019; n = 250 for history, n = 40 for clinical examinations and haematology) also demonstrated equivalent or superior health outcomes for vegan dogs.
Kiemer (2019) surveyed 250 dog guardians, of whom 84.8% used vegan dog food, 14.0% used variations of vegetarian diets, and 1.2% used meat-based commercial dog food. Blood nutrient levels were analysed in 40 dogs, 20 of whom were fed a vegan diet for an average of 2.15 years, as well as a control group of 20 fed a meat-based diet. Total protein, vitamin B12, folic acid, calcium, magnesium, iron, taurine and L-carnitine were tested, although taurine and L-carnitine were only tested in three dogs due to higher costs. Only two dogs in the vegan group had nutritional deficiencies (deceased folic acid). These belonged to the same owner, who reported they were diagnosed with giardia infection shortly after blood sampling. Giardiasis can interfere with intestinal uptake of nutrients (Tilley & Smith 2016, p. 549) such as folic acid. In comparison, 11 dogs in the meat-based group had deficiencies. All 20 dogs fed vegan diets had ideal body weights, and all but one had a healthy skin and coat.
Eight dogs were also placed on a six-week feeding trial, with one group (n = 4) fed a vegan diet, and the control group (n = 4) fed a meat-based diet. Blood tests were performed prior to and at the end of the trial, for the same nutrients, excluding calcium and magnesium, which were not tested due to costs. Within the vegan trial group most nutrient values did not significantly change, but several deficiencies resolved.
When jointly considering the 20 dogs maintained on vegan diets long-term, and the four dogs maintained on vegan diets during the six week feeding trial (n = 24), 66.7% of dog guardians reported that switching to a vegan diet resulted in no change in health status. Health improvements were reported by 29.2%, health decreases by none, and 4.2% were unsure.
Among the 250 dog guardians surveyed, dog health disorders were reportedly absent in 76.8% and present in 23.2%. Ongoing medication was not used by 87.2%, was used by 11.2%, and was not reported by 1.6%. Various health changes while feeding a plant-based diet were reported by 54%, with the great majority reporting improvements. Smaller guardian groups provided information about various conditions. Overall health was reportedly improved by 33.2% (and decreased by 0.8%) of 143 guardians, with activity level reportedly increased by 20.4% (and decreased by 0.8%) of 146 guardians. Reductions in dermatological problems were reported by 26.0% (with increases by 1.2%) of 135 guardians. Healthier and shinier coats were respectively reported by 34.4% and 36.8% of 149 guardians, with less healthy or shiny coats reported by 2.0%, for each condition. Unpleasant dog odour was reportedly reduced by 31.6% (and increased by 0.8%) of 141 guardians. Dental health was reportedly improved by 19.2% (and worsened, by 3.6%) of 142 guardians. Gum health was reportedly improved by 12.8% (and worsened, by 0.8%) of 141 guardians. Decreased bad breath was reported by 20.8% (and increases reported by 6.0%) of 134 guardians.
Kiemer concluded that, “Blood chemistry analysis and physical examinations of the vegan dogs in this study together clearly indicate that a vegan diet can be healthy and adequate for dogs, and in some cases, even improve overall health. The additional data collected from 250 dog owners feeding a plant-based diet strongly supported this conclusion.”
Very few dogs have greater energy needs than sprint-racing huskies. Accordingly, a 2009 study published in the British Journal of Nutrition compared the health, and in particular, the haematological parameters (focusing on red blood cell counts) of six such dogs with six others maintained on a commercial meat-based diet for 16 weeks, including 10 weeks of competitive racing. Haematology results for all dogs were within the normal range throughout the study and the consulting veterinarian assessed all dogs to be in excellent physical condition. No dogs developed anaemia. On the contrary, red blood cell counts and haemoglobin values increased significantly over time in both groups.
In 1994 People for the Ethical Treatment of Animals (PETA) conducted a systematic survey of the health of 300 vegetarian dogs sourced from 33 US states and Canada via PETA’s newsletter (PETA 1994). Dogs ranged in age from young puppies to 19 years old. 88.7% (266/300) were spayed or castrated, and, of those who were not, 22 were male and 12 female. 52.7% (158/300) were female and 47.3% (142/300) male. 55.7% (167/300) were mixed breeds and 44.3% (133/300) were purebred, with a wide range of breeds represented, although a larger number of terriers (22), retrievers (22), beagles (7), and dobermans (6) were present. 65.3% (196/300) were vegan (pure vegetarian—diets exclude eggs, milk and other animal products), with the remaining 34.7% (104/300) simply vegetarian (i.e., ovo-lacto-vegetarians).
Table 1 illustrates the breakdown of vegans and vegetarians by the length of time they maintained a meatless diet:
0-2 years 3-5 years 6-8 years 9+ years
Vegan 31.3% (94) 19.3% (58) 4.0% (12) 5.3% (16)
Vegetarian 22.3% (67) 9.7% (29) 5.0% (15) 3.0% (9)
Total 53.7% (161) 29.0% (87) 9.0% (27) 8.3% (25)
Table 1: Duration of vegetarian and vegan diets of 300 dogs
Overall health status
There appeared to be a distinct advantage to being a vegan or vegetarian for a larger percentage of one’s life—all of the percentages in Figure 1 are greater than for the entire surveyed population.
There also appeared to be a slight health advantage for veganism compared to vegetarianism although this was not tested for statistical significance: 82% of dogs who had been vegan for five years or more were considered to be in good to excellent health, while only 77% of dogs who had been vegetarian for five years or more were considered to be in good to excellent health.
Twenty eight deceased dogs were included in the survey. Excluding the three dogs who either died in accidents or were euthanised for aggression, the median age of death was 12.6 years. The average length of time as a vegan or vegetarian was 5.7 years. The causes of death are summarised in Table 2:
Cancer Heart disease ‘Old age’ Miscellaneous Accidents Euthanasia due to aggression
Dogs 8 7 5 5 2 1
Table 2: Causes of death of 28 dogs
Miscellaneous causes of death included: renal, spinal, liver cirrhosis, euthanasia due to arthritis, and unknown causes.
Incidence of health problems
The most common health problem was infections of all kinds. 11.7% (35/300) suffered some type of infection, with ear infections being the most common (16), followed by urinary tract infections (eight), eye infections (six), and other miscellaneous infections (seven). There was an inverse relationship between length of time as a vegan or vegetarian and incidence of infections:
· No dog who had been vegan for four or more years or vegetarian for more than 5.2 years contracted ear, urinary tract, eye or other infections.
· No dog who had been vegan for more than 3.5 years had an ear infection.
· No dog who had been vegetarian for more than four years had a urinary tract infection.
Urinary Tract Infections
2.7% (8/300) dogs had a history of urinary tract infections, of which six were female and two male. According to a veterinarian contacted by PETA, this figure is somewhat higher than the expected rate of infection (about 1%).
The excretion of the nitrogenous waste products of protein catabolism results in the acidic urine of carnivores. Vegetarian diets with typically decreased protein contents may result in urinary alkalinisation, which increases the risk of urinary stones, which may result in partial or complete urinary obstruction. Alterations in bacterial flora, with increased possibility of urinary infections, may also result (see ‘Urinary Alkalinisation’ below).
The second most common health problem observed after infections was skin ailments, which also constitute the most common illnesses of dogs overall. 11.3% (34/300) suffered from some form of skin irritation (hot spots, flea allergy, dermatitis, etc.), but eight of these were considered to be minor.
The third-ranking health problem was arthritis, with 7.3% (22/300) suffering from this condition. Seven of the 22 dogs had arthritis related to old injuries, such as broken bones. Of the remaining 15 dogs, 13 were 10 years old or older, so the arthritis may have been age-related.
4.7% (14/300) had apparently benign growths, tumours, warts, or cysts, which appeared unrelated to time spent on a vegetarian diet.
4.0% (12/300) had heart problems, and seven of the 12 had died as a result of those problems. Five of the dogs who died of heart problems were 13 to 15 years of age, i.e. elderly. However, the trend for heart disease was the opposite of that for infections, i.e., there was a direct correlation between heart disease and length of time as a vegan or vegetarian: all dogs with heart disease had been vegan for at least four years or vegetarian for at least 10 years.
The most common and serious cardiac disease was dilated cardiomyopathy (DCM). Five dogs (aged five, nine and older), all of whom had been vegan for at least four years, had DCM, which results in myocardial (heart muscle) flaccidity and impaired pumping ability. This potentially fatal disease of the heart muscle normally affects about 2% of all dogs, appearing mostly in large and giant breeds. A small percentage of these lack sufficient cardiac levels of the amino acid L-Carnitine. The amino acid taurine, which dogs, unlike cats, are able to synthesise, regulates the entry of calcium into the myocardium in order to trigger each heart beat. Deficiency may also result in cardiomyopathy (heart muscle disease).
However, recovery is possible with taurine or L-carnitine supplementation. Of the five dogs with DCM, three recovered by taking supplements of either L-carnitine or taurine. Prevention appears possible through regular supplementation with these two amino acids, e.g. via a nutritionally complete vegetarian canine supplement.
A low 3.7% (11/300) were considered by their guardians to be overweight. However, all 11 of these dogs were nevertheless described as in good to excellent health or energetic. The decreased protein and fat levels and increased dietary fibre of vegetarian diets are all effective in promoting a healthier weight.
3% (10) were identified as having digestive problems. Of these, nine were seven years or older, which may have been related to a general decline in digestive enzyme secretion with age, and which is often treatable with enzyme supplementation.
2.7% (8/300) had hypothyroidism, a decrease in serum thyroid hormone levels. However, no dog who had been vegan for more than three years had hypothyroidism, and no dog who had been vegetarian for more than four years suffered from it.
Vision or hearing deficits
2.7% (8/300) were deaf or had hearing loss, but seven of the eight were 13 years old or older. Similarly, seven dogs (2.3%) were blind or had vision loss, but six of the seven were 13 years old or older. Age-related hearing and vision loss is unfortunately normal. The younger blind dog was a collie with congenital blindness.
A low 2.7% (8/300) had cancer. Of these eight, six were 9 years old or older, with the other two being seven years old. The incidence of cancer normally rises with age. The inverse correlation between duration of vegan or vegetarian diet and cancer incidence may have been significant: no dog who had been vegan for more than five years and no dog who had been vegetarian for more than 5.5 years had cancer.
Nutritional yeast and garlic
Dogs eating nutritional yeast and/or garlic did seem to fare somewhat better than the rest of the dogs. 81.6% (102/125) of the dogs eating nutritional yeast were in good to excellent health, compared to 72.6% of those who did not. 83.3% (70/84) of dogs eating garlic were in good to excellent health, compared to 80% of those who did not. Dogs eating either nutritional yeast or garlic also had a much higher incidence of good or improved coats—44% for nutritional yeast eaters and 47.6% for garlic eaters, compared to only 22.9% of dogs not eating nutritional yeast and 17.8% of dogs not eating garlic.
The only other specific food item that seemed significant was soy food products. Since all the commercial vegetarian dog foods eaten contained soy, very few dogs had no soy products in their diets—only 13% (39/300). However, these 39 dogs were in substantially better health than the others. 89.7% (35/39) of the dogs who ate no soy products were in good to excellent health, compared to 74.3% of dogs who ate soy products. Also, the incidence of skin problems was much lower in the dogs who didn’t eat soy—only 5.1% (2/39) had skin problems compared with 10.7% of those who ate soy products. Some dogs are allergic to soy, which may cause skin reactions. Dogs who did not eat soy products relied heavily on grains (oats, rice, bread, and pasta), legumes (chick peas, lentils, split peas, and beans), vegetables, potatoes, and sunflower seeds.
Although tests for statistical significance were not performed, the results suggest that:
- The longer a dog remains on a vegetarian or vegan diet, the greater the likelihood of overall good to excellent health.
- Veganism is more beneficial than vegetarianism.
- The longer a dog remains on a vegetarian or vegan diet, the less likely he or she is to get cancer, infections, hypothyroidism, or suffer from obesity.
- A vegetarian diet may increase urinary alkalinisation, with its consequent potential for urinary stones, blockages and infections; hence regular urine pH monitoring and correction of alkalinisation is important (see below).
- The longer a dog remains on a vegetarian or vegan diet without supplementation of L-carnitine or taurine, the greater the likelihood of dilated cardiomyopathy or other cardiac disease, particularly in large or giant breeds.
- Nutritional yeast and garlic appear beneficial to overall health and coat condition.
- Dogs without soy foods in their diet appear healthier than those who eat soy, which is known to cause skin and other reactions in dogs allergic to it.
Studies opposing vegan or vegetarian dog food: 1
Yamada et al. (1987)
Yamada et al (1987; n = 8) subjected dogs to four hours daily of enforced running at 12km/h for two weeks, following six weeks of rest. The plant-based dogs had lower circulating free cholesterol and suffered anaemia.
3.2 Reported cases
In 2005 it was reported that an English border collie was on track to becoming the world’s oldest dog. Aged 27 (189 in human years), Bramble was still “alert and active and goes for a walk four times a day,” and swam once a week. According to her guardians at the time, Bramble “loves exercise” and “has a real passion for being outdoors”. One stated, “She can be a thorn in my side when she’s restless, but it’s what keeps her going.” Bramble subsisted mainly on a diet of rice, lentils and organic vegetables. Bramble was vegan (pure vegetarian, consuming no animal products at all) (Anonymous, 2005). Perhaps exhausted by media inquiries, unfortunately her guardians declined to return her calls, and I’ve been unable to discover Bramble’s subsequent history.
Apart from the increased overall health, and decreased incidences of cancer, infections and hypothyroidism among the 300 dogs surveyed by PETA (see Population Studies previously), numerous other happy guardians of vegetarian dogs have reported their experiences in Peden’s (1999) Vegetarian Cats & Dogs. The health benefits they reported include decreased ectoparasites (fleas, ticks, lice and mites), improved coat condition, allergy control, weight control, decreased arthritis, improved vitality, improved stool odour and cataract resolution.
Ectoparasites and coat condition
Alison Shepard wrote of her dogs Vanya and Vladimir: “Vanya (age 10) and her son, Vladimir (age 5) have always been vegetarian. Since we’re going to breed Vladimir, we had his hips X-rayed for certification. He got “excellent” rating from O.F.A. — top score! He and his mom have beautiful coats and skin. Here in Florida, skin problems are very common — hot spots, etc. Also, they don’t seem to attract fleas. People assume we “bomb” our house & soak our yard with pesticides, like everyone else seems to. They can’t believe the answer is diet.” (Peden 1999).
Veterinarian Richard Pitcairn (Pitcairn & Pitcairn 1982) quoted a New Yorker: “Friends think I’m nuts to cook for a dog. They have younger dogs with loose or missing teeth, severe rashes, heart and breathing problems, overweight, lethargy, etc. They say Buck is so healthy because he’s a mutt. That might help, but I think the diet and care he gets is part of it also. Buck has never had fleas either.”
Possibly assisted by the proliferation of artificial dyes, flavourings, preservatives (especially ethoxyquin), stabilisers and adulterated slaughterhouse products in commercial meat-based pet foods, the prevalence of companion animal allergies is rising. As stated by allergy expert and veterinarian Dr Alfred Plechner, animal products provoke the most allergic reactions, with beef at the top of the list for both cats and dogs. Changing to another commercial meat-based pet food usually does not resolve the problem, because of the similarity in ingredients used (Plechner & Zucker 1986). Consequently several meatless prescription diets have been formulated to address allergies which may use novel (i.e. not previously encountered) vegetarian protein sources.
Itchiness is the most common sign of a food allergy for companion animals, although vomiting, coughing or wheezing can also be present.
Michael Buzel of Florida recounts the story of his dog, Penny: “I adopted my first dog, Penny (collie/golden retriever mix) from the Florida Broward County Humane Society in 1987. She was four and one-half years old and suffered from multiple allergies that caused her to scratch constantly and gnaw at her backside. She kept losing a lot of hair and generally did not look very happy. I brought her to my first veterinarian who gave her cortisone pills that alleviated the problems. Unfortunately, cortisone causes other problems that are worse in the long run. When she stopped taking the pills, the problems recurred. I thought there has to be a better remedy than medication, so I found another veterinarian who suggested changing her diet. We eliminated all allergic foods (meat, chicken, fish, eggs, yeast, milk, etc.) using a commercial dry and canned dog food. It still contained lamb but Penny’s condition dramatically improved. ….A friend told me about Vegedog and gave me a recipe for a vegetarian dog food (using a lentil base) and told me to supplement it with Vegedog. Penny loves the food and I feel good about the food I’m feeding her. I cook the food every other Saturday morning (it takes approximately two hours start to finish) using two large stock pots. I make a lot because I recently adopted another dog in need of a home (golden retriever) that became a vegetarian when he became a member of my family. I never cooked in such large quantities before but the more I did it, the easier and less overwhelming it became. I freeze portions in large Tupperware containers and defrost as needed. I add Vegedog to their food at each meal, so I’m sure they are getting their nutritional requirements. I wish more people would realize that they could try to help their companion animals with a change in diet like I did (in conjunction with a veterinarian’s advice) which might stop the itching, scratch and hair loss as well as save huge amounts in vet bills. Initially, Penny lost some weight when I changed her diet, but after adjusting her food portions, she is back to normal. Her coat is shiny and she looks happy. She does not suffer from any allergic conditions any more. I also make treats for both dogs and give them carrots occasionally throughout the day for their teeth.” (Peden 1999).
Weight control and arthritis
Obesity is an important and growing problem for domestic dogs. Potentially serious health problems related to obesity include impaired cardiac function and respiratory disorders. As veterinarian Dr. Gregory MacEwen (1989) states, “Obesity can be one of the major conditions which can adversely affect the longevity of a pet.” Vegetarian diets typically contain decreased protein and fat levels and increased dietary fibre, all of which are effective in promoting a healthier weight.
Obesity also predisposes to arthritis. Veterinarian Dr. Michael Lemmon (1991) also holds free radicals accountable. He states, “Free radicals are formed during normal cellular metabolism, when cells take in nutrients, assimilate and utilize the nutrients, and then excrete the waste products. Some of these waste products are free radicals. Wherever you find poor quality foods being eaten, you will also find an excess of free radicals. Rancid fats and moldy grains are two leading sources of free radical production in animals. … Fat is an essential ingredient in any diet. Many commercial pet food manufacturers have problems with controlling the rancidity in fats added to the food they produce. They unsuccessfully use chemicals to try to curb this rancidity. American grain is quite often polluted with varying degrees of mold. Pet food manufacturers, for economic reasons, usually use the lower quality grain products in their pet food. Many cases of arthritis will respond effectively and quickly to antioxidant nutrients such as vitamin C, vitamin E, Beta-carotene, and selenium. Another highly effective antioxidant is the enzyme combination of superoxide dismutase (S.O.D.) and catalase.”
Canadian Gwyn Watson enthusiastically described her experiences: “My two labs and six cats have been on Vegedog and Vegecat for about six months now. I have a golden lab named Janus who is nine years old. He has had arthritis for the past four or five years. Over this time he deteriorated to the point where he could hardly get up the basement stairs and was very stiff and in pain when standing after laying down for long periods. It has been at least three years since he could jump into the back of our pickup. We either lift him in or carry stairs with us. Since being on this diet, Janus has lost over 20 pounds, is now running, and has even jumped into the back of the pickup without assistance. I make the Lentil-Sunflower recipe in large quantities (two 25 pound bags of lentils at a time) and then bake them into loaves and freeze them. That way I only have to make dog food once a month, or even less. I was told one year ago by a vet that Janus wouldn’t last more than a year. My present vet tells me Janus is in excellent shape.” (Peden 1999).
John Grauer of New York described cataract resolution in his 16 year dog Simone: “A couple years ago, she had cataracts — her eyes were cloudy and dull. Recently, I have been giving her some of my own food (pea soup, tomatoes, cabbage, etc.). I always noticed that after giving her vegetables, her eyes would turn a deeper color brown. Finally, I began to realize that her eyes were not turning color, rather, the cataracts were going away! I haven’t been to my vet in a while, but when I go again, I will ask him to look at her eyes. Now they are bright and clear, as far as I can tell. Actually, I think what did the trick was the cabbage. Simone eats cabbage like there is no tomorrow. She eats it raw, cooked, the cores, and any old part of a cabbage. She always wants it, even after she has had her regular dinner! To me, it is kind of funny to see a dog eating cabbage, but that is what she likes (I like it too).” (Peden 1999).
4 Urinary alkalinisation
Concerns have previously been voiced that vegan dogs may experience urinary alkalinisation, predisposing to urolithiasis (urinary stone formation) and lower urinary tract dysfunction (i.e. urination difficulties and blockages). However, recent large-scale studies by Knight et al (2022) and Dodd et al (2022) did not show any increased risk of lower urinary tract dysfunction in vegan dogs. Hence, this concern appears to have been unfounded.
The health hazards to cats and dogs (and, of course, to ‘food’ animals) that are inherent to commercial meat-based companion animal diets are extensive, and difficult to avoid (see Meat based-diets). Additionally, growing numbers of informed consumers are unwilling to financially support the suffering and death inherent to the meat industry, and the environmental damage it causes. Consequently, growing numbers are exploring vegetarian alternatives.
Regardless of the combination of animal, plant, mineral or synthetically-based ingredients used, diets for cats, dogs, or other species should be formulated to meet the palatability, nutritional and bioavailability requirements of the species for which they are intended. There is no scientific reason why a diet comprised only of plant, mineral and synthetically-based ingredients cannot be formulated to meet all of these needs. In fact, several commercially-available vegan diets aim to do so, and have jointly supported a healthy population of thousands of vegan cats, dogs and ferrets (who are also naturally carnivorous) for many years (Weisman 2004). Regardless of the ingredients used however, sound quality control procedures, including regular laboratory nutritional analysis, should be implemented, to ensure products consistently meet these requirements.
As always, the health status of all animals should be regularly monitored, including through annual veterinary checkups, or more frequently if illness arises from any cause, with screening blood tests at appropriate intervals in old age, or where otherwise clinically indicated.
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