Pet Food – Nutritional Soundness and Health Outcomes

Vegan diets for cats – a review of the evidence

Summary

This technical letter, published in a leading UK veterinary journal, summarised the evidence extant by Oct. 2023, about health outcomes of cats on vegan vs meat-based diets. Three studies had shown equivalent or superior health outcomes, when vegan diets were used.

Knight A (2023). Vegan diets for cats – a review of the evidence. Vet Times 53(41), p. 31.

Vegan versus meat-based cat food:

guardian-reported health outcomes in 1,369 cats, after controlling for feline demographic factors

Abstract

Increasing concerns about environmental sustainability, farmed animal welfare and competition for traditional protein sources, are driving considerable development of alternative pet foods. These include raw meat diets, in vitro meat products, and diets based on novel protein sources including terrestrial plants, insects, yeast, fungi and potentially seaweed. To study health outcomes in cats fed vegan diets compared to those fed meat, we surveyed 1,418 cat guardians, asking about one cat living with them, for at least one year. Among 1,380 respondents involved in cat diet decision-making, health and nutrition was the factor considered most important. 1,369 respondents provided information relating to a single cat fed a meat-based (1,242–91%) or vegan (127–9%) diet for at least a year. We examined seven general indicators of illness. After controlling for age, sex, neutering status and primary location via regression models, the following risk reductions were associated with a vegan diet for average cats: increased veterinary visits– 7.3% reduction, medication use– 14.9% reduction, progression onto therapeutic diet– 54.7% reduction, reported veterinary assessment of being unwell– 3.6% reduction, reported veterinary assessment of more severe illness– 7.6% reduction, guardian opinion of more severe illness– 22.8% reduction. Additionally, the number of health disorders per unwell cat decreased by 15.5%. No reductions were statistically significant. We also examined the prevalence of 22 specific health disorders, using reported veterinary assessments. Forty two percent of cats fed meat, and 37% of those fed vegan diets suffered from at least one disorder. Of these 22 disorders, 15 were most common in cats fed meat, and seven in cats fed vegan diets. Only one difference was statistically significant. Considering these results overall, cats fed vegan diets tended to be healthier than cats fed meat-based diets. This trend was clear and consistent. These results largely concur with previous, similar studies.

Knight A, Bauer A & Brown H (2023) Vegan versus meat-based cat food: Guardian-reported health outcomes in 1,369 cats, after controlling for feline demographic factors. PLoS ONE 18(9): e0284132. https://doi.org/10.1371/journal.pone.0284132.

Call for evidence-based positions on vegan diets

Summary

This technical letter, published in a leading UK veterinary journal, sheds light on some of the reason for the British Veterinary Association’s repeated opposition to vegan pet food – they appear to be crucially ignorant of key facts concerning this field. At least they’ve stated they will review their position in the future…

Knight A (2022). Call for evidence-based positions on vegan diets. Vet Times 52(29), p. 19.

The weight-of-evidence position on vegan dog food

Summary

This technical letter, published in a leading UK veterinary journal, summarised the evidence extant by May 2022, about health outcomes of dogs on vegan vs meat-based diets. Four studies showed equivalent or superior health outcomes for dogs on vegan diets (compared to meat-based dog food), and one study (the oldest, smallest) showed a contrary result.

Knight A (2022). The weight-of-evidence position on vegan diets. Vet Times 52(21), 23.

Vegan versus meat-based dog food: Guardian-reported indicators of health

Abstract

Alternative pet foods may offer benefits concerning environmental sustainability and the welfare of animals processed into pet foods. However, some worry these may compromise the welfare of pets. We asked 2,639 dog guardians about one dog living with them, for at least one year. Among 2,596 involved in pet diet decision-making, pet health was a key factor when choosing diets. 2,536 provided information relating to a single dog, fed a conventional meat (1,370 = 54%), raw meat (830 = 33%) or vegan (336 = 13%) diet for at least one year. We examined seven general indicators of ill health: unusual numbers of veterinary vis- its, medication use, progression onto a therapeutic diet after initial maintenance on a vegan or meat-based diet, guardian opinion and predicted veterinary opinion of health status, percentage of unwell dogs and number of health disorders per unwell dog. Dogs fed conventional diets appeared to fare worse than those fed either of the other two diets. Dogs fed raw meat appeared to fare marginally better than those fed vegan diets. However, there were statistically significant differences in average ages. Dogs fed raw meat were younger, which has been demonstrated to be associated with improved health outcomes. Additionally, non- health related factors may have improved apparent outcomes for dogs fed raw meat, for three of seven general health indicators. We also considered the prevalence of 22 specific health disorders, based on predicted veterinary assessments. Percentages of dogs in each dietary group considered to have suffered from health disorders were 49% (conventional meat), 43% (raw meat) and 36% (vegan). Significant evidence indicates that raw meat diets are often associated with dietary hazards, including nutritional deficiencies and imbalances, and pathogens. Accordingly, the pooled evidence to date indicates that the healthiest and least hazardous dietary choices for dogs, are nutritionally sound vegan diets.

Knight A, Huang E, Rai N, Brown H (2022) Vegan versus meat-based dog food: Guardian-reported indicators of health. PLoS ONE 17(4): e0265662. https://doi.org/10.1371/journal.pone.0265662.

The nutritional soundness of meat-based and plant-based pet foods

Abstract

Objective
Global trends such as population growth, increasing competition for protein sources, environmental degradation, and farmed animal welfare concerns, are all driving plant-based pet food development. However, lack of evidence of nutritional sufficiency is inhibiting their uptake. This interferes with the ability of some consumers to adopt pet foods more aligned with their values, and the ability of the pet food sector to fully realise the potential of this emerging market, whilst concurrently reducing its environmental footprint. Yet, no systematic study has been published examining the prevalence of steps taken to ensure the nutritional soundness and quality of pet foods, and whether plant-based diets have lower standards in these respects. Accordingly, we designed a study to explore this.

Materials and methods
We surveyed pet food manufacturers producing 19 meat-based and 10 vegan, almost vegan or vegetarian pet foods.

Results
Although there were there were limited areas in which practices could be improved, most manufacturers had acceptable or superior standards at nearly all stages examined, throughout the design, manufacturing, transportation and storage phases, with plant-based diets slightly superior to meat-based diets overall.

Conclusion
A range of best practice steps should be implemented by companies and regulators, and a comprehensive range of communication modalities implemented, to reassure consumers about the nutritional soundness of products.

Knight A and Light N. (2021). The nutritional soundness of meat-based and plant-based pet foods. Revista Electronica De Veterinaria 22(1), 1 – 21.

Vegetarian Versus Meat-based

Diets for Companion Animals

Summary

Many owners of companion animals are interested in vegetarian diets for their animals, as concerns increase about the consequences of animal farming, for health, animal welfare, and the environment. However, are vegetarian diets for cats and dogs nutritionally balanced and healthy? This article comprehensively reviews the evidence published to date from four studies that have examined the nutritional adequacy of vegetarian diets for cats and dogs. To obtain additional information, we surveyed 12 pet food companies detailed in the most recent study. We also examined the nutritional soundness of meat-based companion-animal diets, and reviewed the evidence concerning the health status of vegetarian, carnivorous and omnivorous companion animals. Both cats and dogs may thrive on vegetarian diets, but these must be nutritionally complete and reasonably balanced. Owners should also regularly monitor urinary acidity, and should correct urinary alkalinisation through appropriate dietary additives, if necessary.

Knight, A. and Leitsberger, M. (2016). Vegetarian versus meat-based diets for companion animals. Animals 6, 57.

Summaries

 

 

Vegan Diets for Companion Animals

Circulation 1.2 million people.

Knight A (2018). Vegan diets for companion animals. The Healthy Pet Guide. Distributed with The Mail on Sunday, 14 Oct. 50 – 51.

How to Safely Veganise Your Cat or Dog

One page summary by the Vegan Society (New Zealand).

Knight A (2018). How to safely veganise your cat or dog. Green for Life, winter. 16.

Fishy Business?

A humorous, thought-provoking examination of the controversial issue of vegan diets for cats and dogs. Includes a discussion of the health hazards and benefits of meat-based and vegan diets, a discussion of natural feeding behaviour, and advice for guardians of vegan animals on safeguarding their health.

Knight A (2008). Fishy business? Lifescape, May, 74-76.

Vegan Animal Diets: Facts and Myths

A summary published on The Vegan Society (UK) website.

Knight A (2015). Vegan animal diets: facts and myths. The Vegan Society [UK].

Debate About Vegan Cat Food

a series of letters in J Amer Vet Med Assoc, 2005.