Date Published: January 15, 2019
Publisher: Public Library of Science
Author(s): Sarah A. S. Dodd, Nick J. Cave, Jennifer L. Adolphe, Anna K. Shoveller, Adronie Verbrugghe, Jan S Suchodolski.
People who avoid eating animals tend to share their homes with animal companions, and moral dilemma may arise when they are faced with feeding animal products to their omnivorous dogs and carnivorous cats. One option to alleviate this conflict is to feed pets a diet devoid of animal ingredients—a ‘plant-based’ or ‘vegan’ diet. The number of pet owners who avoid animal products, either in their own or in their pets’ diet, is not currently known. The objective of this study was to estimate the number of meat-avoiding pet owners, identify concerns regarding conventional animal- and plant-based pet food, and estimate the number of pets fed a plant-based diet. A questionnaire was disseminated online to English-speaking pet owners (n = 3,673) to collect data regarding pet owner demographics, diet, pet type, pet diet, and concerns regarding pet foods. Results found that pet owners were more likely to be vegetarian (6.2%; 229/3,673) or vegan (5.8%; 212/3,673) than previously reported for members of the general population. With the exception of one dog owned by a vegetarian, vegans were the only pet owners who fed plant-based diets to their pets (1.6%; 59/3,673). Of the pet owners who did not currently feed plant-based diets but expressed interest in doing so, a large proportion (45%; 269/599) desired more information demonstrating the nutritional adequacy of plant-based diets. Amongst all pet owners, the concern most commonly reported regarding meat-based pet foods was for the welfare of farm animals (39%; 1,275/3,231). The most common concern regarding strictly plant-based pet foods was regarding the nutritional completeness of the diet (74%; 2,439/3,318). Amongst vegans, factors which predicted the feeding of plant-based diets to their pets were concern regarding the cost of plant-based diets, a lack of concern regarding plant-based diets being unnatural, and reporting no concern at all regarding plant-based diets for pets. Given these findings, further research is warranted to investigate plant-based nutrition for domestic dogs and cats.
Human diets minimising (‘ovo-lacto vegetarian’, ‘vegetarian’) or eschewing animal products completely (‘strict vegetarian’, ‘vegan’) have been increasing in prevalence worldwide in the past decade [1–3]. Motivations reported for this shift away from animal products include health concerns, sustainability/environmental preservation and empathy for non-human animals [4–6]. These motivations are certainly not unfounded. The many health risks associated with human consumption of animal products, including coronary heart disease, stroke, type 2 diabetes, obesity, and a variety of cancers, are becoming widely appreciated by the scientific community and general public [7–12]. The environmental impacts known to be associated with our dietary choices are similarly well documented [13–15], and people are also becoming increasingly concerned about the environmental impact of modern pet foods as well . Traditionally, commercial pet foods were derived mostly from animal and plant by-products from the human food industry, which has been considered a highly sustainable practice [17–19]. However, with many pet owners now seeking by-product-free and meat-centric foods, there may be direct competition with animal products otherwise destined for the human food chain [17, 18]. With regards to empathy for animals, people who have chosen to abstain from eating animals have been reported to possess stronger empathy for non-human species than people who consume meat [20, 21].
A multiple choice and short answer survey titled “Pet Feeding Practices” was administered online (www.surveymonkey.net). To minimize selection bias, no reference was made to any particular type of diet or feeding practice in the title or introduction of the survey. The study was supported by the research ethics board of the University of Guelph (REB #17-08-029). The questionnaire started with multiple-choice questions [MCQ] collecting demographic data (age, gender, country), pet owner diet (omnivore, pescetarian, vegetarian or vegan, with descriptions of each diet) and pet type (cat, dog or both). An omnivorous diet was defined as one that included meat; pescetarian was defined as including fish but no other meats; vegetarian was defined as avoiding all meat but including eggs, dairy and/or honey; and vegan was defined as being devoid of all animal products. The next series of MCQs also included an open-text option of ‘other’ where the pet owner could input their response. These included locations where pet food was sourced (supermarket, pet store, veterinary clinic, direct from manufacturer, online, homemade, ‘other’) type of pet diet, treats/snacks/scraps fed in addition to the pet’s diet, and concerns regarding pet foods. Type of pet diet was categorized as commercial or homemade; meat-based, vegetarian, or vegan; raw or cooked; and, in the case of cooked commercial diets, kibbled or canned. While the term ‘meat-based’ is not entirely accurate, as many pet foods utilise animal by-products not conventionally considered ‘meat’, such as offal, blood or bone meal and also typically contain a large amount of plant ingredients, this was utilised within the survey text for simplicity. Similarly, the term ‘vegan’ was utilised to refer to pet foods within the text of the survey in order to be easily identifiable. The meaning, however, of the term ‘vegan’ is defined by The Vegan Society as a lifestyle/philosophy, and not simply a diet . Thus, the phrase ‘plant-based’ is used within this paper to describe pet food devoid of animal products, as it is recognized that neither dogs nor cats are free to choose their lifestyle. Feeding frequency of each type of diet was also determined, with pet owners reporting feeding any type of diet either ‘daily’, ‘often’, ‘infrequently’ or ‘never’. Respondents could choose from a list of possible concerns regarding meat-based pet foods: farm animal welfare, farm animal rights, health concerns, environmental concerns, social concerns, and ‘other’; and plant-based pet foods: unnatural, unhealthy, not nutritionally complete and balanced, cost, moral acceptability, and ‘other’. When ‘other’ concerns reported fell within one of the listed categories, these were adjusted in the dataset. For example, mention of cultural or religious practices were included in the ‘social’ concerns category, while concern regarding origin or quality of ingredients was included in the health-related categories. Examples of ‘other’ concerns which were kept within the ‘other’ category include: concerns regarding palatability and unawareness or unavailability of different diet options. For pet owners who indicated that they did not feed a plant-based diet, an extra MCQ was included to ascertain whether they would feed a plant-based diet if one were available that met their standards or desired attributes. For those who indicated they would not feed a plant-based diet even if it met their specific stipulations, a follow-up open-text option question was then asked to differentiate between individuals harbouring further concerns regarding plant-based diets and rejection of the diet based on non-cognitive negative affective response . The survey ended with a set of questions to assess financial motivation of pet owners to feed a commercial plant-based diet, if one were available to them. For pet owners with both cats and dogs, questions were first answered regarding their dog, then their cat, and then finished with the generic questions regarding purchasing of plant-based diets. The questionnaire was piloted on 15 volunteers and questions adjusted as required to improve survey.
A total of 3,718 questionnaires were commenced, of which 3,673 were complete enough to include for statistical analysis. Those not included were due to attrition prior to identifying type of pet. Survey participants comprised 1,871/3,673 (51%) dog owners, 602/3,673 (16%) cat owners, and 1,200/3,673 (33%) owners of both dogs and cats. Pet owner demographics are presented in Table 1. The survey questions were considered independently, so the number of responses for each question differed, thus proportions are representative only for the number of people answering each question. For example, pet owners who had only cats were not included in data analysis regarding dogs.
At this point in time, the diet of most pets included animal products to some degree. However, of those pets fed diets which included animal products, some were regularly fed vegetarian and plant-based foods with occasional animal-derived foods added. Twice as many dogs as cats were fed exclusively plant-based diets. This higher prevalence of plant-based feeding to dogs was not unexpected, considering the more flexible omnivorous physiology of dogs, and the relative lack of commercial plant-based diets for cats. Perhaps counter-intuitively, in this study, meat-avoiding pet owners appeared to keep cats in preference to dogs, though this only reached significance in vegetarians and not vegans. This may be a reflection of some intrinsic preference meat-avoiding pet owners have for cats, particularly since it was found that vegetarians were both more likely to keep cats, and less likely to keep dogs. However, considering the obligatory carnivorous physiology of cats, one may expect pet owners who themselves avoid meat to also avoid having pets who eat meat, though this was not supported by the findings of this study. Other reasons for cat preference among vegetarians may be regarding lifestyle, such as living in a smaller home in an urban setting . Indeed, urbanisation has been found to be correlated with meat avoidance . Other lifestyle factors such as life stage (single vs. couples), size of household, and income may also contribute to the increased prevalence of cat ownership amongst vegetarians. In the USA, cats were preferred over dogs by singles and households with lower income . Similar patterns in terms of life stage, size of household, and household income have also been identified amongst vegetarians, though these factors were not investigated in the current study [55, 56]. Similarly, pescetarians, people following a diet which excludes meat from land animals but includes fish and other marine creatures, who kept cats were found to be more interested in feeding a plant-based diet to their pet than were pescetarians with dogs (Fig 3). It may simply be that the relative dearth of plant-based options for cats leaves more cat owners wanting a suitable alternative, thus inflating the number of those who do not currently feed a plant-based diet but would do so if one were available. Alternatively, this may again represent an association between meat-avoidance and cat-ownership, indicating a possible avenue for future investigation. Regarding the relative lack of commercial plant-based options for cats, comparatively more cats were fed a homemade plant-based diet than reported in dogs, though the sample size was very small. Despite the small number, this finding is particularly concerning, as complete and balanced homemade diets are challenging for pet owners to make even with the inclusion of animal products [25, 57–65], while homemade vegetarian and vegan diets have been considered contraindicated in cats .
This study represents the first investigation into the prevalence of meat-avoidance in the pet owner population. The prevalence of vegetarianism and veganism was higher in the pet owner sample than has been reported in the general population, accounting for approximately 12% of pet owners in the sample population. To put that into perspective, in the USA alone, with its population of 325 million  and a national a pet-owning rate estimated at 56% , there may be as many as 20 million vegetarian and vegan pet owners. Given that the concerns regarding animal-based pet foods reported by vegan and vegetarian pet owners surveyed appear to be the same concerns that they feel regarding animal-products in their own diets, a large number of these pet owners likely desire alternative diets for their pets. Indeed, nearly one-quarter of vegan pet owners reported currently feeding their pets a plant-based diet, while almost half of those who indicated they did not currently do so reported that they would if there were a plant-based diet available which met their standards. For the majority of pet owners interested in feeding a plant-based diet to their pet, the major obstacle was a lack of evidence of nutritional sufficiency. These results suggest a discordance between perceived or real availability of suitable plant-based pet foods and the demand for evidence-based complete and balanced plant-based pet foods. It is clear that an association exists between the diet a pet owner has chosen to follow and the diet they choose to feed their pet. Nutritional sufficiency of most plant-based diets has yet to be demonstrated, while few studies have investigated the short or long-term effects of plant-based diets on pet health. Considering the number of pet owners found to be feeding, or interested in feeding, plant-based diets to pets, and the implications on pet health, nutrition, and the pet food market, more research is warranted regarding plant-based foods for dogs and cats.